How to 'correctly' measure the complexity of the grammar of a language?

Question: Linguists have some methods to measure the complexities of the grammar of a language. Some linguists may refer to how many grammar rules that language has.    some may also refer to how many morphemes a single word has in that language , while other linguists may also refer to how many grammatical cases a language possesses . Okay let's go straight to the point, Polish is hard to learn because it possesses so many grammar rules and word changing, same for czech and Lithuanian . American indigenous and some caucasian languages are hard to learn because they possess so many morphemes in their single word (Abkhaz and Adyghe verbs are perfect examples). While Hungarian, and northeast caucasian languages like Tabassaran, and Tsez are hard to learn because they possess so many grammatical cases, with Tsez being the most extreme with 126 cases ( depending on one's analysis). My question is, What are the best methods to measure the complexity of the grammar of a language ? . What is the hardest language on earth to learn in terms of grammar complexities based on that method ?
Comment: I don't think linguists actually do generally consider the "complexity" of a language to be meaningful.
Comment: There isn't anything approximating to an agreed measure for the complexity of a language, let along a "correct" one. Most linguists regard attempts to measure the complexity of a language as a complete waste of effort.
Comment: The average number of morphemes is a measure of the language's *morphological* complexity. That doesn't mean it's a global measure of linguistic complexity. Linguists generally don't care about global measures or find them meaningful.
Comment: The problem is that everybody actually speaks their own language and then tries to pass as a speaker of whatever. So there are **vast** individual differences in language-learning capabilities. I know some people (granted, they're all linguists) who can pick up a language and have a useful conversation in it in a few weeks. And I know some other people who can't get past their native speech patterns, and never get fluent in any other language. No matter what languages we're talking about. That's why asking about hard languages is the wrong question. For some, they're all hard.
Comment: You've basically answered your own question, now you're asking us to vote for which metric is best, in our collective subjective opinion.
Answer: I haven't the slightest idea what the answer to you question might be.  I think you're wasting your time with such speculations.  Basically, I guess, you think the difficulty of a language must be somehow proportional to the length of a grammar book written for that language.  I don't think so.
Details of vocabulary are a great labor for dictionary makers and grammar writers, but humans don't learn languages by reading dictionaries and grammars, though those may be helpful.  Instead, humans have a fantastic ability to remember such details about words -- it's not hard for us.
Answer:
Linguists have some methods to measure the complexities of the grammar of a language.

Methods to measure the complexities of different aspects, absolutely.

What are the best methods to measure the complexity of the grammar of a language ?

That's the problem: there is no best method.
It's like asking "which cultures on earth are the most complex?" Different cultures, like different languages, are complex in different ways. Some languages have extremely complicated systems of derivational morphology, others have tables and tables full of inflections, and still others have syntax full of movement rules.
And most importantly—complexity in one of these areas tends to lead to simplicity in others. Languages with complicated inflection systems tend to have a freer syntax, for example, while languages with complicated syntax don't need as many inflections.
Now, it is possible to find a language that's simple in all of these respects: look into the early stages of trade languages and pidgins as they begin their evolution into creoles. They tend to start with very straightforward syntax, and almost no morphology at all. But as time goes on, they tend to start gathering complexity, since deeper syntax and morphology make it easier to communicate complicated ideas. Eventually, they reach the level of other natural languages, and tend to rest comfortably there.
P.S. If someone were to actually make a metric of "language complexity" or "language learnability", specifically excluding orthography (since that tends to come later), I would expect all well-established natural languages to be hovering around the same level. The process of language learning puts strong selection pressures on languages, keeping them complicated enough to express elaborate concepts, but simple enough to be learned by speakers. As a pidgin develops into a proper living language, these pressures are what push it to take on more and more intricacies until it reaches that same vague level.
Comment: This last paragraph is also my assumption; glad to see it written out by someone who knows far more than me what they are talking about! ^^
Answer: a) What you exemplify is an inductive argument, you have seen or heard of people who have a hard time learning the grammar, and you assume it were the grammars fault. Native speakers might think quite differently, though. What you are looking for is either a reductive (rule based) argument, which would lead to a kind of Universal Grammar base line type system common to all the languages in comparison; Or a deductive argument based around typology. I hope I did not mix-up the two.
b) In physics there is a duality between Measurement, Control and Regulation. Your question for measurement suffers from a loose definition of the system that you want to measure. In other words, you meant to ask for a definition of grammar-complexity. Since grammar is multi-facetted, there is very likely--in my humble opinion--no lossless projection onto a single dimensional measure. Only Euclidean spaces have the unique norm. However, since there is no concensus on whether language grammar were, in some dark corners, a context-free grammar in the sense of Chomsky's hierarchy, thus NP-complete, and since NP-complete problems cannot be modeled in Euclidean spaces, though they can be approximated e.g. via schema of induction, I would not be too sure that your question has an answer.
Sorry for the rant, I am just trying to show the scope of the problem. Put another way, a language with only two words and a really simple construction rule can have a hell of a run-time complexity, but it's rules are really simple to describe.
Answer: [updated here] READ THIS ARTICLE:   Entropy Rate Estimates for Natural Language—A New Extrapolation of Compressed Large-Scale Corpora
One can try to evaluate complexity of a written word by calculating its Shannon entropy. This type of complexity is related to Kolmogorov complexity, they might be equivalent.
One approximate way of doing it is by compressing the text and then calculating its entropy rate. If you want to compare the languages of your choice, then you can skip the entropy parameter and stay with the size of the compressed text file.

Obtain a corpus of translated works [e.g. legal documentation, official announcements, the Bible, etc.], the files must be fairly large;
All files must use the same encoding system, with constant number of bits per character;
Use opensource general-purpose lossless compression algorithms/software to compress those files; do that with the disabled use of system or software dictionaries, those must be generated by the algorithm at work.
Apply statistics to calculate errors of those measurements.
Comment: A link to "this article" is not really useful. Could you add author, title, and publication information of the article to the link anchor?
Comment: Calculate the entropy with respect to what, though? Characters, syllables, phonemes, words?
Comment: How does this determine the *grammar* complexity? It is well known that the very same literal works need more or less characters when translated to some other languages. Does that mean that such a language has a more / less complex grammar?
Comment: 1. Entropy rate with respect to bits. 2. You can calculate the amount of information per character. And yes, it is a very indirect way of evaluating the complexity of a grammar.
Comment: Oh, Vladimir, exclude the original work.
Comment: Look up the concept of Kolmogorov complexity.


rename tag: randomized-algorithm -> randomized-algorithms

Question: the tag was created, deleted(?), and then re-created with a typo, and it does not let me change it. (it says something alike 'the randomized-algorithms cannot be created since randomized-algorithm already exists.. raise this issue in meta')
Comment: Yea, seen that before. The system protects itself against too similar tags. Mods can rename tags; Shog9 has done that for us in the past, I am sure he will again. :)
Comment: I don't think the tag is particularly suited for [this question](http://cs.stackexchange.com/questions/570/generating-uniformly-distributed-random-numbers-using-a-coin), but it is ok.
Answer: I'll take this opportunity to discuss randomness-related tags.
I don't see how randomized-algorithms applies to this question: it's about generating random numbers. A randomized algorithm is one that uses random numbers, not one that makes them: quicksort pivot, probable primes, …
This question should be tagged random-number-generator: although it's not about a PRNG per se, it's about generating random numbers with a particular distribution.
On top of these, we may or may not want a more general tag: random (like SO) or randomness (like CSTheory and Crypto).
Comment: I don't agree with you on this. I read that question in the following way: "Given a random binary string, how can I construct an algorithm to do XXX" (here, XXX is output uniform numbers within range given by input, that is XXX in this case is "RNG"). This is clearly a randomized algorithm. Most of the answers there describe a las-vegas algorithm, my answer describes a monte-carlo, but all are algorithms. One can discuss their expected run time, expected amount of randomness needed, failure prob, etc.
Comment: I agree with Gilles here, and I don't like the general tags. The notion of Las Vegas and Monte Carlo algorithms does not apply here as the desired algorithm does not have a correct output; we require a property of a sequence of outputs. I think your retagging edit, @RanG., was premature.
Comment: @Raphael the field of randomized-algorithm is very broad. It contains many subfields: las-vegas algs, monte-carlo-algs, but also,  analysis of required randomness for specific task. Other related subfields are extractors ("purifying" randomness), and pseudo-random generators. I think all these can be tagged as randomized-alg (the last two better be "crypto"; anyways most of the crypto algs are probabilistic). I think the question should be edited to be clearly a CS question and not MATH question, and this THIS should be the point of the discussion.
Comment: PS. I didn't mean my retagging to be "one sided action" and I'm sorry if it is considered as such. Remember that all is editable, and it'll be changed as needed according to our discussion (if you prefer, it can be rollbacked now and set after the discussion...)
Comment: Discussion rekindled [here](http://meta.cs.stackexchange.com/questions/1099/what-about-tags-random-and-randomness).


What kind of software can be used to remove Rootkit.Sirefef.Gen?

Question: My System has the rootkit Rootkit.Sirefef.Gen. I would like to know how I can remove this rootkit.
Comment: Your Windows installation disc is the best solution. Boot on it, format your drives, reinstall. Problem solved.
Answer: Rootkit.Sirefef.Gen is not a specific specimen of malware as such. The '.Gen' typically means the AV scanner has picked it up through generic heuristic algorithms as something that looks like Sirefef (ZeroAccess) rather than 100% matching a specific signature.
There is a large extended family of trojans that would trigger a detection like this and no way to know what exact strain you have, so no way to tell for sure what, if any, AV would reliably remove it. Because this is a well-known family you would hope that most competent AV should be able to remove it, but it's always possible you have some variant that differs and might not be 100% removed - and you would have no way of knowing.
As usual, if your machine has been compromised the only certain way to recover it is to reinstall the OS from scratch.
Answer: I figured out a way to thwart rootkits though it will not totally remove it. I simply added a malware process destroyer into my boot sequence. I used Rkill, as this program was able to detect the malware. However, after deleting it, the rootkit would generate the files again on startup.
By putting rkill into my startup I effectively rendered the rootkit inert. Assuming the rootkit is faster than rkill, I was thinking (though I didn't actually get a chance to) that in task manager you could set the priority of rkill to high and that of the malware to low.
As a sidenote, though it slows startup, having rkill in there isn't a bad idea for general malware defence.
Rkill can be downloaded from bleepingcomputer:
http://www.bleepingcomputer.com/download/rkill/
Goodluck.
Answer: Most Security companies offer free rootkit removal utilities. Off the top of my head, I can remember Malwarebytes, Kaspersky (called TDSSKiller), Bitdefender and Intel (formerly McAfee).
Download any of those, preferably from a different computer, install it on a USB and boot it on your infected computer (some of them run inside Windows, I would recommend running at least one USB based version though, because rootkits have full administrator access, and can cause problems.)
Malwarebytes Anti Malware is also a decent on demand scanner, if you want to use it, make sure to check the "scan for rootkits" checkbox. Don't rely on it for rootkits though.
RKill apparently only terminates the process of the rootkits. You should run whatever your antivirus is afterwards.


docker mysql container not running suddenly

Question: docker mysql container was working perfectl.But after restarting of the server and using the start command to run the conatiner it is not working.My other containers are all up and running as normal.But mysql shows status exited.If I do docker start conatiner id it takes the command.But I am unable to enter into the container .Please find the attachment also
Answer: Without seeing the specific error it looks like the container's runtime process is either crashing or exiting.  When a docker container's runtime process exits the container stops.
 You can get more information about the specific error by using the docker logs command:
docker logs 92455a993a54


Select Contour by Length

Question: I am a real beginner with QGIS 2.8. I am able to generate a contour map from a raster DEM, but the contour map is very 'busy' because the land form is pretty flat. There are lots of short contour loops that clutter up the output which would be easy to remove if there was a way to select all contours greater than a certain length. QGIS is able to determine the contour length if I inspect a particular contour line, but this is a 'derived' value, and I do not find a way to use this derived value as a selection criterion.
Comment: Welcome to GSE ! Please try to add more context with the DEM source (if possible) and the tools used under QGIS. Have you a particular reason for begin with QGIS 2.8 ? If you want to learn using QGIS, I recommend you to start with the latest LTR 3.4 : https://qgis.org/en/site/forusers/download.html
Comment: Can you please explain what GSE stands for.I would start with 3.4 but am nervous of installing programs that haven't made it to my distributions repository
Comment: GSE stands for Gis Stack Exchange, this site ! Since 2.8, QGIS have made great updates.
Comment: I bit the bullet, upgraded from Mint 18.2 to Mint 19.1 and now have QGIS 3.6 installed. Thank you for your suggestion.
Answer: There are several way for that
If you just want to select line shorter than 500 you could use  $length <500 (or  $perimeter <500 if you're working with polygons) as an expression in the select by expression (the 500 is the length in the layer CRS unit, if you want 500m made sure to use a projected CRS whose unit is meters)
Alternatively you could calculate a length field in the attribute table using $length as expression (you could either create a new field (no auto-update if you edit the line but the value are added to your layer) or create a virtual field (auto-update on edit but the value only exist in this specific QGIS project, also usefull if you don't have edit rigth and can't add a new field).
After calculating the lenght you could select or symbolise by attribute as usual
Comment: Fantastic! Using 'Processing Toolbox' > 'GQIS geoalgorithms' > 'Vector selection tools' > 'Select by expression' and putting in your suggested query I have got exactly what I wanted. Thank you
Comment: OK, done. I had to look up on Google to find out how to do this!

Select Contour by Length


is "non-intrusive code-behind" a good or bad practice?

Question: I am a bit surprised that while learning WPF/XAML/Silverlight almost all of the XAML/C# examples I have encountered have the "Click" events in the XAML and very few in the Window or Page constructor.
With all the emphasis these days on "non-intrusive Javascript", I would think that more developers would actually be structuring their XAML/code-behind like this:
XAML:
<Grid>
    <Button x:Name="btnEdit"/>
</Grid>

Code behind:
public Window1()
{
    InitializeComponent();

    btnEdit.Content = "Edit";
    btnEdit.Click += new RoutedEventHandler(btnEdit_Click);
}

private void btnEdit_Click(object sender, RoutedEventArgs e)
{
    btnEdit.Content = "This button was clicked.";
}

Any thoughts on why this would be a good or bad practice?
Answer: Most of the smaller WPF examples give just an impression what is possible without focusing on design issues or good style.
In real world applications XAML should only be used for declarative programming. For example, binding a command to a button or declaring a data binding. Karl Shifflett has some great articles about the MVVM pattern which separates the concerns of your WPF/Silverlight application very well.
Code behind is in my opinion just suitable for tiny applications. It tends to mix view, control and data.
Answer: If I remember correctly, I think that there is a partial class which implements the Init code above that is code gened by visual studio.  I can't speak for WPF, but it does this in ASP.Net 2.0, so I'm assuming that it does it the same here.  It took me forever to get used to this.
I agree.  I hate defining events in the markup.
Answer: I agree with your concern.
After much debate, we are following a similar pattern of non-intrusive, ultra-lean XAML and binding commands and data in code-behind.
If you add events in the XAML there is a contextual menu navigation to the event code. If you bind commands in XAML there is no equivalent. You can navigate from the command declaration in the XAML but not where it is assigned to the Command property on a control.
Answer: MVVM is bad practice.
You think that you separate Data and View. And what? Total mechanism with XAML binding, binding commands, translating it to methods and implementing INotifyPropertyChanged for what? For UTests (I made - I test conception he-he)? Right software need in only in user's test... It's your code separated in such way in which you sometimes do not understand where is what.
For what you use INotify? For what Microsoft ALL WPF controls and entities as whole in WPF wrote inherited from FrameworkElement with magic DependencyProperties?
Multiple binding is hard resource technique by the word (read authors of MVVM).
I wrote high complicated 3D CAE system without any Patterns less than year...
with classic organization of app with classes and code-behind.
https://skydrive.live.com/?cid=ea6ad1087e3103f0&sc=photos&id=EA6AD1087E3103F0!103&sff=1#cid=EA6AD1087E3103F0&id=EA6AD1087E3103F0!118&sc=photos
All the samples in MVVM are about Customers in Company...
I offer put the name MVVMCC pattern (Customer in Company)


Sewer Terminator model from Genisys?

Question: what was the model of sewer terminator that john connor killed while saving kyle reese in Terminator:Genisys?
Answer: It was a 600 series.  You can tell because its skin was rubbery and clearly fake, an indicator that it's a T-600, the first infiltrator model.
Also, the scene had a callback to the Resistance's future use of dogs to detect Terminators vs. humans.
Comment: tnx, i thought so as well.. besides, T800 were new at the time kyle reese was sent to 1984 so we are probably correct... i found some comments that it is T800 cause of the plasma rifles but i don't think so...

Sewer Terminator model from Genisys?


Q&A section, what is it exactly?

Question: @Terdon has requested a Q&A section on a rolling thread on an investigation about gene duplication. What is exactly meant by this and how to go about doing it?
Comment: By the way, I realize this is asking you to do a lot of work and I entirely understand if you don't want to spend even more time on this. I just can't think of any other way of keeping the really useful content you created :/
Answer: Thank you for posting this, I was about to bring it to meta myself. First, a quick summary of what happened. @Michael G answered this question but in a way that didn't give a definitive answer. Instead, Michael did what most of us are very accustomed to doing, both online and in real life: he gave the OP very useful pointers based on his extensive expertise, and asked some very relevant questions that would help him provide an answer.
The problem is that these sites, the SE network, don't do discussion well. Not only because it is against the "rules" and not only because we try to have a high signal to noise ratio, with one question and everything else being answers to that question. Another issue is that, unlike traditional online forums, the SE site mechanics don't guarantee the order of the answers. So when you have two users having a back and forth discussion, referring to "the post above" or "the post below", the post they are referring to will move depending on how the person visiting the page is sorting the answers.
So, coming back to the specific example, when I saw that this had happened I converted one of Michael's answers to a comment, I incorporated the OP's answer to his answer into the original question and deleted the rest since they had, by now, moved on to a new Q&A.
However, this new Q&A was also treated as a discussion, resulting in a bit of a mess. It now has 5 "answers", but all of them are part of a back and forth discussion between Michael and the OP. The kind of thing we're all used to doing in forums, but the sort of thing that's really not a good fit for this site. Finally, they moved on to a third Q&A, which you can find here: How to make a robust amino acid phylogeny with adequate robustness support.
As a moderator, I'm in a bit of a fix now. On either of the other two sites I moderate, I would simply close these questions as too broad or delete them outright as not following the rules of the site. However, those other sites are mature, with a lot of content and this would be a drop in the ocean. We're a much newer and sparser site, and I am very reluctant to delete outright. Not only do we need content, this is really excellent content, dammit! It's just in the wrong format. Michael spent a considerable amount of time providing very valuable help, and the OP was responsive and came back with all the detail Michael asked for. This may be a bit of a "trainwreck" (by SE standards) at the moment, but I think we could actually make a truly useful Q&A out of it.
That's why I suggested that Michael and/or the OP could maybe collect all the steps into one question. Ideally, the OP would post a new question, but this time, they would include all the detail that came out of this long discussion in the question itself. That way, Michael could distill the long conversation into one comprehensive answer to the now very comprehensive question.
I am very open to other ideas though. This was just the best way I could think of to both preserve the Q&A model and preserve what seems like a very useful exchange of knowledge that could help future readers. In their current state, the threads are unlikely to help others since it's very hard to keep track of what was said in answer to what.

How this should have been handled according to the SE model
With this sort of situation, the best solution is to first try and get the extra detail needed in the comments, but when that's not enough, we have the following options:

Invite the OP into a chat room (one will be created automatically if you start having a back and forth in the comments). Sort out the details there, get the extra information, and then come back and edit it into the question so the question is now in a form that can be directly answered.
Ask the OP to break the question into smaller parts. Ask the first step in one question, then everything else in follow-up questions.

Quick links for anyone trying to understand:

1st question
2nd question
3rd question
Comment: The chat room should have been first port of call, I'm not 100% how to do this but I'll figure it out. Summarizing everything into one question will be tough but maybe doable. Let me see
Comment: @MichaelG. you can create a room by visiting http://chat.stackexchange.com and clicking on the "create new room" button at the bottom of the page. However, new users won't be able to chat since you need to have at least 20 reputation (across all SE sites) to post in chat. In such cases, either ask one of the mods to explicitly grant the user access (any SE mod can do this) or start in the comments and wait until the system asks you if you want to create a room (happens after a few messages between the same 2 users). That room will always be accessible to the OP.
Comment: Thanks @terdon, but I did some time ago for "phylogenetics" and someone deleted it. Next time the OP is around we'll chat. The easiest thing for now is I will review and edit the questions to be complaint to SE format and feedback here.
Comment: Rooms with no activity are deleted after a while (several weeks or even a few months). That might be what happened.

Q&A section, what is it exactly?


I can't use the 3d manipulator

Question: I can't use the 3d manipulator - whenever I attempt to drag the handles Blender simply repositions the 3D cursor.
Answer: In my experience (my laptop has this issue) it's a problem with OpenGL implementation affecting the selection. This causes dragging the manipulator to result in repositioning the 3D cursor instead of manipulating the object.
To resolve this you need to change the Selection option in the System tab of the User Preferences :

In my case, changing from 'Automatic' to 'OpenGL Select' resolves the issue.
Answer: I had the same issue on my laptop, and managed to fix the issue by turning off "Proportional Object Editing Mode" which looks like a little blue circle in the toolbar at the bottom of the page. (Shortcut O)
I discovered this because whenever I started a new 3D model with factory settings, the 3D manipulators would work perfectly fine, so I simply went through and copied all of the factory settings onto my project (I messed with a few things trying to fix another problem) and this was legit the last change I fixed and it was the only thing that made a difference for me.
EDIT: I know this post is old, but I thought I'd leave this here for anyone else experiencing the same issue.

I can't use the 3d manipulator


Merge "Citations" and "bibliography" tags?

Question: Is there a distinction between the citations and bibliography tags? Both refer to either citing something or adding it to the bibliography, which are essentially one task (everything cited is added to the bibliography). Are there any counter-examples or edge cases I missed? Can these be merged?
Answer: The citations tag is written up as

Queries related to citing or referencing published or unpublished sources.

used for questions about citing and citations, not necessarily in th econtext of a bibliography (reference list). The Bibliography tag says

Questions related to the structure, building and typesetting of a bibliography comes under this tag. Bibliography is an organized

So both are useful as I see it. I think that the citations tag may be used wrong and so there is probably reasons for checking tagging more carefully. There are also quite a few tag wikis that are not written up which may contribute to confuion since it is unclear what they represent.


Hiding an answer/vote on the blockchain

Question: I understand that every transaction is visible on the blockchain but would it be possible to create a DApp that allows people to vote in disguise? not showcasing their vote till the votingprocess is over?
Answer: You are looking for commitment schemes. Generally a commitment scheme has two phases: commit and reveal phase. A simple commitment scheme is the following:

Commit phase: if Alice wants to commit to a value x, she has to generate a random r (let's say r should be more than 100bits) and send H(x||r), where H is a cryptographically secure hash funciton and || stands for concatenation). Since H is cryptographically secure, it is computationally infeasible to find a preimage of  H(x||r) (i.e. it has a negligible probability). This property is called computational binding. This property ensures that no one (not even Alice) can alter Alice's commitment value x.
Reveal phase: Alice reveals her choice x' and r'. Bob checks whether H(x||r)==H(x'||r'). If it matches then accept, otherwise reject.

Other more elaborate commitment schemes could be built using the discrete log problem.
Comment: Let's say I have 5 people placed in hot chairs and they need to vote 'yes' or 'no'. All but one individual places the vote 'yes'. After x amount of time, I want those votes to be visible and not till then.
Comment: Well, you need to reveal all of them, otherwise you won't be able to tell which one is 'yes' or 'no'. Just looking at the commitments you can not distinguish between votes. That is the point of commitments...
Comment: Oh yeah, sorry maybe i worded it wrongly that was perfectly clear to me. What I meant was that the votes should not be decryptable untill revealed. Once a vote is commited it should stay secret till revealed and then everything commited is revealed at once. I think using commitment schemes might be the way to go in my case then
Answer: This is possible, but not directly. The most simple way would probably to store the hash of the single vote for each voter. You can use the hash property hiding to hide the vote: If you have possibilities "Yes" and "No", each voter appends a random secret string to either "Yes" or "No" and uploads the hash of the resulting string. That way, the hash does not reveal the vote, until the voter reveals the secret appended string and his vote. If revealed, everyone can confirm that the vote was not altered by checking the hash.
A more sophisticated solution can be build with homomorphic encryption. That removes the need for each user to reveal the secret after the vote has ended, but is a little bit more complicated.
So in the end it depends on you application.

Hiding an answer/vote on the blockchain


How could we estimate the square footage of a room from an image?

Question: I wonder if it would be possible to know the size of a room using image, I don't see anything about this subject, do you have some idea how it could be done?
Comment: Producing a floor plan (that's essentially what you want to do) using images is possible even if somewhat difficult, there are apps which do that. However, they work from collections of images taken from defined viewpoints, I don't think that working from just one image can work as there always are hidden areas that could have totally different geometry from the visible part of the room.
Answer: Welcome to AI.SE Hadrien!
A possible approach is:

Gather many example images of rooms for which you know the square footage. Record the square footage of each room together with each image.
Pick a machine learning model that is well suited to learning relationships between images and numerical outputs, like a Convolutional Neural Network.
Train a machine learning model using an optimisation algorithm, like gradient decent. In the case of training a CNN, this algorithm starts by setting up the network with randomly chosen connection strengths between different 'simulated' neurons. It then exposes the network to an input image, and observes the number the network outputs in response. The algorithm then makes small adjustments to the strengths of the connections in the network, so that if the network were exposed to the image a second time, it would output a number that was less wrong (i.e. closer to the correct square footage). By repeating this process many thousands of times, and with many images, the network eventually becomes quite good at guessing the square footage of new images that it hasn't seen before.

In practice, the network is quite likely to pick up on any patterns in the images that correlate with square footage, not necessarily the ones you want. For example, it might pick up on, say, the fact that humans in the picture are usually a good object to guess at the scale of the rest of the room.


UK tax for foreign freelancer

Question: I am a Vietnamese freelancer. I have UK based clients who I am doing work for whilst I was here in Vietnam (totally working remotely with 6-month contract). The earning and salary will be transferred to my Vietnamese bank account. Do I need to pay UK tax as a freelance foreigner? I am currently sifting through their website but would appreciate some immediate feedback.
Comment: No, you don't have to pay tax in the UK. I don't know the rules in Vietnam but probably you will be asked to pay tax in there. It is your client's responsibility to justify the expense.
Answer: You pay taxes where you live. You do not pay taxes where your customers/clients live.
I don't know about Vietnam, but traditionally you pay taxes where you live, not where clients live. You would pay Vietnamese taxes based upon your income. You would not pay UK taxes since you don't live in the UK.
Comment: Comments are not meant for extended arguments. If you feel the user is incorrect, use [chat]. If you feel the answer is correct, upvote.
Answer: The first question is: Do you get a salary or to you write them invoices?
If you get a Salary, they should have to look after the formalities. Though that may be different in you country.
If you get paid on a freelancing basis, which I presume since  you posted here, you have to look after the formalities.
If this is considered a B-to-B transaction you customer probably needs to register  and pay VAT under the reverse-charge procedure.
If you deal with private customers you´d have to register in the EU vor VAT. If you are not able to do this, there are Payment providers wich are and can invoice for you, but that will cost you a fee.
For definitiv answers pleas consult a tax adviser, as legal counseling is out of scope here.

UK tax for foreign freelancer


Can you block calls on the iPhone?

Question: I have an iPhone 4S running iOS 5 and cannot find (after trying) any app that blocks calls. Is there anything out there that can block calls on the iPhone?
Comment: Blocking a call happens at the carrier level. Any 3rd party app that advertises the ability to block calls does so using hacks that, in effect, quickly answer and then just as quickly hang up on the caller without notifying you (no ringtone). Seamless is open for interpretation. Apple is in the business of making terrific products, I see very little reason they would "be all over this."
Answer: I have not found a 3rd party application that does this well. You can obviously block a number via your cell carrier. Since I could not find a good method to block calls with an application I ended up adding the number to be blocked to my contact list and assigned a "silent" ring tone to the contact. Although it will not block a incoming call it will cause the phone to play a silent ringtone when the number in question calls. Not a true block caller solution but at least a potential workaround.
Answer: Up until iOS 7, the only solutions for actual call blocking on the iPhone required a jailbreak.
However, it's not that difficult to find an alternative:

New Contact into which all unwanted phone numbers are stored
Assign a silent ringtone to the new contact.

Can you block calls on the iPhone?


How did Shelob stab Frodo through his mithril shirt?

Question: How come Shelob's sting was able to pierce through the Mithril armor worn by Frodo and poison him?
Answer: Shelob stung Frodo in his neck, which was not covered by the mithril shirt that he wore.

As he had run forward, eager, rejoicing to be free, Shelob with hideous speed had come
  behind and with one swift stroke had stung him in the neck. He lay now pale, and heard no voice, and did not move.
The Two Towers: The Choices of Master Samwise
Comment: this explanation does not apply to the movie canon, in which she stabs him in the abdomen
Comment: Movie plot-hole then, canon is the books


Why does a stomach come before the gizzard in birds?

Question: Since the gizzard is for mechanical digestion, shouldn't that happen before the stomach digests the food with acids? (to make the morsels smaller)
Answer: The gizzard appears to be a structure that bird inherited from a distant ancestor, as the structure is found in dinosaurs (which birds are derived from) and crocodilians.  https://en.wikipedia.org/wiki/Gastrolith
As to why, the bird gizzard is not in a better position, (like say the grasshopper gizzard which is located in front of its stomach), the best reply I think off is evolution is blind.  The innovations that appear, are random and further constrained by the features that the animal already has.
It is probably the same reason why rabbit eat their own poop to better digest their food, even though cows have evolved a four chamber stomach to handle the same problem of digesting grass. Or why no animal has evolved a second set limbs to fly even though it would be super useful to keep arms to catch prey and not sacrifice said arms to be made into wings.
In a sense these questions of why didn't evolution design it better is evidence that the concept of intelligent design is rubbish. Designs in animals (and bacteria) can be really really dumb.
Comment: *"...found in dinosaurs (which birds are derived from)"* This is incorrect. Birds **are** dinosaurs.
Comment: Birds are a derived species of theropod. And theropod are only one of two members of Saurischia. And there is deep divide between Saurischia and Ornithischia. Secondly Birds are a derived species....while they have many features of theropods... the evolution of flight has cause birds to gain many features not shared by most member of theropods. Birds have no teeth, reduced jaws, no grasping fore limbs,a truncated tail, a bird hip, an arrangement found in Ornithischia. Birds are a derived species, avian dinosaurs.


Is it safe to polish aluminum rims?

Question: Everyone loves polished aluminum, but you typically have to pay a good 30% more for it vs. any other finish. Since polishing is a simple process requiring widely-available tools, I thought I could probably get away with taking care of it myself on a some dull-finish or anodized rims. My concern is that I would remove enough material with the polishing wheel to affect the structural integrity of the rim walls, especially on newer rims that are built with very tight strength-weight tolerances.
Comment: The problem is that the anodized surface is there for a reason -- it makes the surface less subject to corrosion.
Answer: If you're actually just polishing, you should remove very little material. I recently polished aluminium to a mirror finish in work (a very different setup as I had to keep the surface perfectly flat as well, but it's indicative). I removed only about 10 microns (but that's the limit of my Vernier calipers).
Braking abrades rims more than this, which is why rims usually have wear indicating grooves, which are considerably deeper.  If you try to polish out deep scratches you might reduce the life of the rim, but look out for the wear indicators which should still show plenty of depth. If the bike is very old it might not have wear indicators. If you don't have wear lines, or you're polishing a face that's not used for braking, you should be careful to remove the absolute minimum material.
If you've got ultra-light rims not designed for rim braking, caution suggests you don't do anything to them. But the combination of aluminium, light weight, and disc brakes would be rare.
You also need to be absolutely certain to remove any polishing residue, and to make sure that you don't make the rim slippery. I'd start by doing the back wheel, and a section of the wheel on both sides, then clean it up and test ride it. You don't want to feel a difference in back braking as the wheel rotates, whatever the conditions. This will also indicate something else: The finish might not stay nice at long as you'd like. Brake pads grind the rims. Slowly but enough to unpolish the surface before long.
Comment: Great info, thanks! I had considered masking off the MSW somehow, but dont want any tape adhesives to get cooked on. I'll probably just try to be careful, and pass some heavier grit over the sidewall after. I'm just trying to polish new rims, so I will just be removing enough to get a shine, nothing more.
Answer: I would not try to polish off an anodized finish. It's hard and you would probably have a difficult time getting it off evenly.
For bare aluminum - go for it. Note that the AL may have a clearcoat finish on it already though.
Polishing will take off very little material - nowhere near enough to change the strength of a rim significantly (assuming you are starting with a fairly high grit - at least 800). I'd clearcoat the polished surface with polyurethane, making sure to keep it off the braking surface.
Comment: I saw some articles by professional detailers where they used a relatively heavy-grit sandpaper (ca.800) to prep an anodized surface before moving on to polishing with a wheel. Seems like a better option than using caustic degreasers to stri[ it.

Is it safe to polish aluminum rims?


Used Space Ark Purposes

Question: So we have a space-saving species that build an space ark to survive a cataclysmic event on their homeworld and save their species. They have successfully terraformed the new target planet but now have a 3 space arks to maintain. Assuming they don't want to colonize another planet what are potential uses for these spacecraft?
Comment: [Get rid of all those](https://hitchhikers.fandom.com/wiki/Golgafrinchan_Ark_Fleet_Ship_B) telephone sanitizers, account executives, hairdressers, TV producers, insurance salesmen, personnel officers, security guards, public relations executives, and management consultants. Now you have only two space arks to maintain.
Comment: We're having a mega-sale on gently used, single-owner, Space Arks RIGHT NOW! Come on down and get your own space ark now! Hurry, while supplies last! This sale ends Sunday! Sunday! Sunday! so you best get here fast, because these ships are OUT OF THIS WORLD!
Comment: Low-income housing.
Answer: Strip it for parts
Your ship is going to be large and will be made up of many processed pieces: support beams, shielding panels, appliances, computers, plumbing, conduits, electrical and data cables, generators/engines/reactors, etc.
Strip it for parts. Even if you have to dismantle it in space and then shuttle the parts to the surface, doing so is probably faster than all of the steps necessary to build those things on the ground: locating raw materials, digging mines, building processing/refining plants to process the raw materials (without the processed materials to do so)...
So repurpose anything and everything you can from the arks to start your colony on the surface. Shields become walls and roofs. Appliances and computers are reused as-is. Generators too.
These won't last forever. But they should last long enough for your colony to build out the infrastructure necessary to create their own.
Recycle
Even the materials you can't reuse as-is can be recycled into the raw materials for other things. Melting down the steel to make new materials is going to be faster than mining, refining, and then making new materials from local resources.
Space infrastructure
Maybe some parts of the ship are left in orbit. Why not keep some parts of the original ship up there and build it out as a science station? Or as a weather observatory? Or to build/deploy satellites? Explore other planets in the system?
Maybe the stripped-down arks become mining vessels, sent out to recover asteroids because that's more environmentally safe than surface mining on your new colony world.
Some combination
Probably, you're going to end up with a mix of all of the above. Much of the ships are brought to the surface to serve as first-generation dwellings while everyone works to start food production and the critical industries necessary to become self-sufficient. But some parts will be just melted down / torn apart / etc. to make raw materials. And the left-over skeletons become ships capable of exploring the new solar system and/or mining non-habitable worlds/asteroids to supply the new colony.
Think of it like this: Why worry with the additional weight of packing flat-pack shelters and furniture and appliances when the ship will be full of them? Much easier to keep using what you have than to build new.
Comment: I was writing something similar to the "strip it" answer, but decided not to post it because the OP explicitly specified the planet had been *terraformed* - which means the colonists probably already had to set up massive planetary industrial bases in order to do so. +1 for going ahead and putting it up anyway.
Comment: Definitely "Some combination" - given the enormous material cost and bulk of the mission anyway, the ships would be designed to have a lot of dual-use parts, or you have to make/transport even more.  By the time the terraforming is complete their internal power sources, water infrastructure, hydroponics, sleeping facilities etc. will have to have been shipped down to the surface.  Probably slowly as the surface becomes viable, and some spare capacity would be needed during the process of colonising from orbit.  They'll be hulks anyway.
Comment: Strip most of the useful parts for the colony, send the engines and substructure out to an asteroid belt, bolt a load of asteroids onto it, return to orbit,???, profit.
Comment: Probably it was incrementally stripped during the terraforming process.
Answer: Colony ship, again x 3!
The thing about getting your homeworld cataclysmed: it induces a certain fear that you could get cataclysmed again.  And fool me twice, shame on me.   Putting all the eggs in one basket is not the best strategy.
And here are these low mileage arks, good to go and with plenty of tread left on their space tires.  Also: their terraformer teams learned a ton doing up their New Target Planet, but now just sit around talking about the glory days, collecting their pensions.  Getting that crew off world would be good.  And there are a bunch of young folks who are keen to make a new world of their own, with a name more hip than New Target Planet.
Each of the 3 arks is sent off to three new potential homeworlds, with the goal of replicating their initial success.  There is a bit of a competitive fraternal spirit between these three.  But also a lot of love and as opposed to the first time when all there was back home were radioactive zombies, this time each of the 3 can support each other, and also be supported by their folks on NTP.
Comment: Good answer overall, but the question specifically said they aren't interested in colonizing other planets
Answer: I think CaM is on the right track with the infrastructure bit. Why waste 3 perfectly good, ready made space station/mining platforms? As they are arks, even with the space-saving nature of the people (or am I interpreting that wrong?), they would still be fairly large which could be good for an orbital hub of some sort.
Obviously the tech base is there, so regular space travel could be a thing (or possibly not, is civilian space flight a factor?). Turning one into a mining hub near the whatever counts as the main resource area and another into a transit hub orbiting the planet could work well. Depending on the drive emissions and size of the resource haulers, you might not want them entering your atmosphere.
If your people haven't yet discovered the virtue of pacifism or, conversely, have discovered that the universe will do it's very best to kill them, then perhaps a large, mobile, military command and control/emergency management facility is warranted as well.
Answer: History
Why not keep it as a monument or even make a museum out of it? The future generations will surely appreciate that. It will stand for a new beginning. A first step. But it will also remind the people that they had to leave their old planet and whatever mistakes led to that, they have to be better.
Answer: Live in them
Your colonists have just spent generations traveling to, and then terraforming this new planet. They've lived on the arks all that time, and the arks don't suddenly become uninhabitable just because you no longer care to use the engines. Many(all?) of your colonists have no idea what living on a planet is like anyway. Some would prefer to stay in space, they can always visit the planet, after all.
Comment: "have no idea what living on a planet is like anyway" - 100 percent it is a certain thing
Answer: Manufacturing
There's lots of things that can be done in microgravity that are more expensive/difficult to impossible in a planet's gravitational field. Growing many types of crystals, making "perfect" ball bearings, etcetera. Plus, getting rid of waste gasses and heat is trivial.
Health Care
Burn victims, cardio-pulmonary issues and the like will be easier to live with and provide lower risk settings for recovery in weightlessness.
Max Security Prison
It's a lot harder to escape and "blend in" when you have to leave orbit in a small shuttle. If the prisoners riot, just start lowering the oxygen level.
High Risk Research
Say you want to play with space warps, nanotech or genetics. Here's an isolated place to do that with lower risk of it endangering the population.
Answer: So you're all done terraforming and probably feel like having a bit of a symbolic gesture to celebrate you're done and not going anywhere else in a hurry - so how about some really good fireworks to celebrate.
Feels like option,

Bring some/all of them in on a steep (enough) reentry (after all we don't want another cataclysm on our hands)
Presumably there's also a sun.
Oh and if you haven't met your new inter-planetary neighbours yet - maybe keep a spare.
Comment: Dropping something is the Sun takes an awful lot of fuel
Comment: Given the nature of the journey there was probably a bit left in the tank. However that's a fair point it might be reusable.
Answer: Frame challenge.

They have successfully terraformed the new target planet but now have a 3 space arks to maintain.

Actually they have successfully terraformed the planet BECAUSE they scrapped the ships.
Just like Hernan Cortes in Veracruz, at the beginning of his conquest. Why did he do it? Because retreat is easy if you have the option. Because having an exit strategy means being able to not really commit to the project. Because after generations of comfortable living in the controlled environment of the ship it is scary to go down to an unknown, hostile world and work hard there to make it habitable.
But what is needed is exactly acting with determination, in spite of fears.
This is an extremely dangerous action for a whole population, aye. But completely needed.
How you do it is up to your story. The leader(s) could just issue orders if they were to have te authority Cortez had (he had to hang and lash to get his way) or simulate an incident or (even better) a terrorist attack. Why the last is better? because it gives the population the threat they need to gather around the leader(s) and be guided down to the planet towards a bright future....

Used Space Ark Purposes


16 by 8 Keyboard matrix

Question: I am working on a project, trying to construct an 80 button keypad. My problem is how to multiplex it so that i only feed the arduino with two sets of BCD or binary(whichever is easier) which are supposed to drive a 75 led display board simultaneously with a pair of 7 segments. The led display board is remote, which means i should drive the boards serially. The other 5 buttons remaining out of 80 are for other functions such as clear last number etc.
Please help!

Thank you very much guys. To answer FuaZe, it is 16*8 but will not use the whole 128 buttons. These extra buttons are for future expansion. The input should consist 16colums and 8 rows. The remote output board is a led matrix numbered from 1 to 75, arranged in a 15colums and 5rows. The same display board is to have a two digit 7seg display. The remote board is to be accessed serially so as to use few cables.
When I press a button on the matrix, say column 5 row 2 the number 20 should appear on the 7seg plus a correspondind diode on column 5 row 2 to light. In short if is a bingo board with numbers 1 to 75..
Comment: Why is the name of the question: "16 by 8 keyboard matrix", 16*8 does not equal 80 buttons?
Comment: Yes, 16x8 = 128 as either 16 outputs multiplexed by 8 inputs, or vice versa, and maybe multiplexing the 75+2x7 segments as another 10 by 7.  Seems like 16+8+10+7 =  41 pins it would fit easily on a 54 IO pin mega.  Maybe you want a 80 button multiplexed input, along with multiplexed 8x10 and 7x2 outputs?  Tell more about the remoteness requirement and the board vs boards requirements.
Comment: Ask your favorite internet finding service about "charlieplexing keys". This may help to connect more keys using less pins.
Answer: Easiest would be to use 2 arduino's, which are connected in some way.
One of them should tell the other one what to do. I suggest you make the one reading the buttons the "master" and the other one it's "slave" device.
You could use 8 inputs, for each column and 10 outputs for each row.
Then you check all 8 inputs per column (pretty rapidly) and then you'll be able to read every button.
You could choose to either send changes or just every value to the slave device.
The slave device would have to do something similiar, but with 2 outputs, to address the right LED's/segments.
Alternatively you could use shift-registers.
There actually are a lot of tutorials on this to be found on the web.
You should check out "Arduino multiplexing" or "Arduino led cube" tutorials.
Answer: Another option would be using both shift registers and port expanders, like Adafruit's MCP23017 I2C Port Expander.
You can use that for the buttons, just get a few of them and hook them up on the I2C bus and you have over eighty pins for the price of 2! If you choose to use the previously stated expander, you will also benefit from Adafruit's library.
Then, use a shift register for your LEDs, using one of the pins that is not I2C.
Note: Pin expanders can handle input and output. Shift registers are only for output!
Good luck!
Comment: Actually there are shift registers for input as well - such as the CD4021B by Texas Instruments: https://www.ti.com/product/CD4021B. It's widely supported (for example arduino library: https://www.arduino.cc/en/tutorial/ShiftIn) and has a 16 bit version as well

16 by 8 Keyboard matrix


Double slit experiment observation

Question: In the double-slit experiment, if you shoot particles through the slits one by one and observe which slit they travel through, is there still an interference pattern on the screen behind the slits? If not, then how is our observation of the particle different than any other object in the universe being affected by it? Doesn't our observation of an event have essentially the same effect as any other object in the universe being affected by the event?
Answer: No, if you observe which slit they traveled through then there is NOT an interference pattern. The act of observing, or more accurately, the need for the location of the electron to be resolved causes it to take on a definite position and then continue on from that position as a particle.  If it is not observed or interacted with in some way that would make it's position relevant to subsequent events, then it's position is not resolved and it continues on as a probability wave, which results in an interference pattern.
Answer: The interference pattern indeed appears also if you send the quantum particles one after the other through the double slit. This essentially is the proof that the interference pattern is not an effect of several particles interacting with each other.
But yes, it is not specifically the observation by a human (or other conscious being) which kills the interference, but merely the availability of the information in principle. That is, if your particle interacts with something else, and the interaction is of a way that the other object differs substantially whether your particle went through the left or right slit, then your interference pattern disappears. You can even make the interference patternm just less pronounced by having the difference in the external object sufficiently small; that is, there is not really a binary "interference pattern or no interference pattern" but you can gradually tune between full interference pattern and no interference pattern.
Answer: Strangely enough, when you do a quantum mechanics experiment, you get a result that says something about what you already know.  If you place a detector at one (or both) of the slits, you watch individual particles go through the slits, and you get a particle result from your detector (e.g., no interference pattern).  If you don't know which slit the particles are going through, you get a wave result (an interference pattern), which essentially tells you that you have no information regarding which slit the particles are going through.  This type of experimental result has bothered physicists since the very early days of quantum mechanics, but it implies that for a quantum mechanical experiment, the experimenter is part of the experiment whether he wants to be or not.
Comment: Hi David, it is site convention not to add the name of the poster at the end of any post.
Comment: Gaurav, I've never visited this site before, so I was unaware.  Thanks for the information.

Double slit experiment observation


IP addresses and Subdomains?

Question: If a school has an IP that's like 10.0.x.x, and a department in that school has it's own site that's an extension of the school's site, does that department's IP just change the last two numbers in the IP?
Does the school have to purchase extra domain space?
Could I have additional addresses established at my IP address, just by changing the last numbers?
Am I completely wrong with my idea of IP numbers?
Comment: This does not strike me as a CS question but more a sysadmin problem. (Also, your question is probably covered by Wikipedia; did you read anything before asking here?)
Comment: I did read Wikipedia before asking here.
Answer: As we are talking about IPv4 addresses here, you have to consider two things:

Usually, your Internet Service Provider (ISP) will assign you one IPv4 address. This can either be changing (the common case for private households) or static. However, there is usually one IP address at a time that you can be reached from the outside of your network.
Internally, you can organize your network independent from those policy. For this purpose, some standard IP ranges like 192.168.*.* and 10.*.*.* are reserved to be used arbitrarily by the local network administrator.

Hence, it is up to the network administrator how the additional department is included in the school's local address space.
Generally, you want to talk of different loosely coupled networks in terms of subnets. To determine a certain subnet, you specify a subnet mask, which fixes the first $n$ bits of an IP address as "the network's address".
So, the admin would assign the additional department a "network address" of, e.g., 10.0.54.0/24. This means, the first 24 bits of this IP identify the network and everything after the 24th bit can be assigned arbitrarily to the devices of that network. In this particular example, any device with an IP address between 10.0.54.1 and 10.0.54.254 would be logically seen as part of the network 10.0.54.0/24.
Assuming that the whole school is connected to some kind of router (which uses NAT to "translate" the local IP addresses to the global IP address assigned by the ISP, roughly speaking), it is then up to the router configuration whether the department is reachable directly. This router will most likely run a web server or delegate http requests to a device of the network that runs a web server. Based on the configuration of this delegation or request processing, you can instruct the router to delegate any request to, e.g., department.myschool.com to the web server of the department and then you are fine.
However, you have to have a top level domain for this, even with a wildcard contract such that every request to *.myschool.com is forwarded to your school's router, that then can decide to forward requests to department.myschool.com accordingly.
Another way to have this flexibility would to use different ports for different web servers in your local network. But this would burden anyone who is interested in your department's website to guess or somehow know the port your web server is listening to.
Comment: It is noteworthy that institutions such as universities will *not* use NAT in order to enable people to have globally accessible machines. In that case, you *have* to honor the institutions address space, otherwise packages don't reach you (because routing is done according to the convention).

IP addresses and Subdomains?


Should I insulate above a suspended ceiling or in the attic?

Question: In our old house the drywall on the kitchen ceiling has to be replaced due to water damage. Original walls are 10' tall. Previous owners dropped the ceiling two feet to hide wires, plumbing, etc. At this time there is no insulation in the attic. Plans are to have some blown in soon. My question is should I insulate between the ceiling joists which is 2 feet below the attic floor or will the insulation blown into the attic suffice ?
Comment: Are you saying that you have a suspended ceiling or a lowered drywall ceiling?
Comment: It's a lowered drywall ceiling. The original ceiling is still there. I just wondered if when they blow the insulation in the attic and if we insulate between the lowered ceiling joists would that 1. Be necessary and 2. Cause any issues
Answer: It's not common to see insulation below a hard ceiling (immediately above a suspended ceiling--even if it's drywall). That space is considered "conditioned".
However, if your dropped ceiling is in effect a hard ceiling, it may make sense to insulate at that level. To do so reduces the conditioned space volume and would be more efficient.
It's going to depend on access and the structure around that room, as well as wall insulation and HVAC configuration.
In response to your comment, it wouldn't be a problem to insulate the lower ceiling as long as you have a continuous blanket through to the ceiling in adjacent rooms.
Answer: Yes, you can insulate above the "suspend" ceiling. (To me, a "suspended" ceiling is a ceiling that has panels that can be lifted out of a framework and a "drop" ceiling is a ceiling that is furred down (framed down) below another ceiling.)
However, if you insulate above a suspended ceiling, you'll always have the possibility of insulation fibers falling down every time you move one of the panels. Also, you'll need to insulate the perimeter of the room where the ceiling "steps up" to meet the adjoining higher ceiling. (You'll need to use "batt insulation" not "blown in insulation" too.)
I like the idea of insulating the lower ceiling because it's less volume to heat, but that's minor compared to the issues of not insulating the perimeter walls of the room from the lower ceiling up to the higher ceiling and losing heat that way. I think I'd insulate at the higher ceiling height and know it's completely insulated. Keep it simple...


From where did Cain get his wife?

Question: I want to know that where did Cain Son of Adam and Eve get his wife? As there was nobody except Adam and Eve after he killed Abel.
Comment: so,ok like seth had 'laid" with his sister?Im just trying to figure out where our generation started.and I got as far as seth married his wife..? where did she come from?I stopped cause ,now im confused??
Answer:
As there was nobody except Adam and Eve after he killed Abel.

Some source of this claim? Because Genesis says:

And the days of Adam after he had begotten Seth were eight hundred years: and he begat sons and daughters (Gen 5, 4).

According to apocryphal Book of Jubilees, Cain's wife's name was Awan.
Comment: "Daughters" is plural, so Adam and Eve apparently had at least two girls. The wording of Gen 5:4 could be taken to mean that they had "sons" (again plural) after Seth, and Seth was born after Cain and Abel, so that could mean three named sons plus at least two more. Note Cain, Abel, and Seth are mentioned by name because of their roles in the first murder. The other children's names are not given because they are not part of any specific events included in Genesis. The vast majority of the people who lived in "Genesis time" are not named, just as most people living at any given time are ...
Comment: And to those who believe in the literal interpretation of Genesis, adam lived more than 900 years! If we only live about 80-90 years and some have 4 or 5 children, imagine Adam and Eve! Also God gave them a command to fill the Earth so i'm pretty sure it would have been more than 5 children.
Comment: ... not mentioned by name in the history books.
Comment: @ Jlaverde @Jay  you both forget that Cain was barnished from 'the face of the ground' which Cain indicates its severity in a protest against it but which he still had to submit to, not mentioning that only a foolish and careless parent  would let go of their child to marry a known killer as Cain who on whim murdered his brother. So wherever Cain settled was a punishment for the wife to endure with him, like a marriage btn a death row convict and  a free woman who never committed an offence.
Such is the case you're suggesting in the daughters of Adam marrying Cain.
Comment: @witness In our own time, murderers and other criminals routinely manage to find girlfriends and wives. "This would be a foolish thing to do" is not at all the same as "it is impossible that anyone would ever do this". Men in prison today sometimes get married to women who can only see them on visiting days. Cain's case would have been less extreme because he was not locked up anywhere; he was exiled. There was nothing to prevent him having a real relationship with a wife.
Answer: Adam and Eve: The Only Humans Without Parents?
Sin is said to come from one man (Ro 5:12). Adam (and Eve) are pointed to as the "source" of sin/death. The curse that God pronounced upon them in Ge 3 after they disobeyed God affects us because we are their descendants and will inevitably sin (Ro 3:23).
God didn't immediately make Eve in the same manner as he made complimentary genders for the other animals. Ge 2 tells of how God showed Adam that he was alone before creating Eve. If God created other humans who were not descendants of Adam and Eve, did he do the same for them? Would he need to?
Would these others have been in the Garden of Eden, too? When did they sin (presuming they did), and when were they expelled from the garden?
@Jomet, Typical readings of the text suggest that once created, every plant/animal reproduced in the manner in which God designed "after [its] kind." There's no other mention of God (re-)creating any of the creatures (or creating more than one pair). While the text does not exclude the possibility, the mere fact that they are never mentioned (or referred to by other Biblical authors, who occasionally refer to elements of tradition for which there is no mention in the OT) is a reasonably strong suggestion that there weren't any others.
Attempting to make room for other humans who weren't descendants of Adam and Eve is not completely impossible, given what's written, but it certainly requires crafting some complicated stories to fit the facts if there were any.
It really sounds like the Biblical account leaves very little room for other people being created simultaneously.
Cain's wife was almost certainly a descendant of Adam and Eve (most likely their daughter).
Answer: From Genesis 4:14 ESV

14 Behold, you have driven me today away from the ground, and from
  your face I shall be hidden. I shall be a fugitive and a wanderer on
  the earth, and whoever finds me will kill me."

This appears to suggest that there were "others" besides Adam and Eve.  While someone could take the story of Adam and Eve literally as the first humans, it doesn't imply that they were the only humans - just the only humans that we talk about.
Therefore Cain's wife MAY have been one of the "others".  Else there would have been an incestuous relationship:

Cain was the first born son of Adam and Eve, and Abel was the second.
  In Genesis 4 we read how Cain kills his brother and is sent east of
  Eden where he marries a woman and "lays" with her. Because Adam and
  Eve were the first humans – assuming ONLY humans – Cain's wife
  was his sister – and, consequently, all of the early Biblical
  relationships were incestuous (with the exception of Adam and Eve).
Comment: What about *Gen 3:20 The man called his wife's name Eve, because she was the mother of all living*. Sounds like Adam and Eve were the first
Comment: do you have any proof to say? they were the only humans!
Comment: I do not have proof to say that they were the only humans.  I thought I left both options open in this answer.
Comment: Oh... and don't try to find proof, you'll run in circles.  Have faith.

From where did Cain get his wife?


Which rabbinic or halakhic relief is offered to agunot?

Question: Where is there a discussion about a rabbinic or halacha-based relief offered to agunot?
There appears to be none mentioned here at Mi Yodea. Correct me, if am wrong. Please include sources, for my learning.
Answer: The "old-fashioned" agunah was one where the husband disappeared at sea or the like, and there's insufficient proof of death. As hazoriz mentioned, the Talmud allowed for weaker forms of proof than we might otherwise require, to make it easier for her to remarry. (Still, the rabbis have to be solidly convinced that the husband actually died.) Such questions came up with the sinking of the Titanic, and most recently, on 9/11/2001 with the collapse of the Twin Towers. Rabbi Jachter has an article on that one here; Rabbi Mordechai Willig in New York corresponded with Rav Ovadya Yosef zt'l on some of these questions. Hacham Ovadya wrote some similar responsa about Israeli soldiers who went missing in action.
Next comes the case where the husband's sanity is questionable. A rabbi will make the best attempt they can to make a determination on this; Rabbi Moshe Feinstein had to deal with a guy who claimed he was the Mashiach and sometimes walked around naked; he spent hours and hours trying to: a.) determine whether the fellow was sane enough to give a Get b.) convince the fellow to then do so, at which point he immediately handled the Get there in Liuban, even though normally they preferred to go to a bigger city with more of a history of doing Gittin. The Beth Din of America had the sad case of a husband diagnosed with very aggressive Alzheimer's; they said he should give a Get while he still had the mental capacity to do so.
The third case -- and the most common one today -- is where the husband is alive and well, but chooses not to give a Get. Theoretically, in some cases a Bet Din can order "coercion" against him, and the Mishna even talks about beating him up. (We then use a very creative reading of what's called "giving the Get of his own free will!") In Israel today, if the Bet Din has found "coercion" to be called for (and perhaps some batei din could be more courageous about making this decision), the Israeli government can take away the man's passport, driver's license, and ability to hold a bank account. One time he was already in jail, and they took away his television!
In America, the community can and will protest outside the fellow's house and business and otherwise shun him, which American law allows them to do. American law does not allow them to beat up the fellow, so please don't do that. (One rabbi was recently caught by the FBI for this and sent to jail.)
In both England and New York State, rabbis have successfully lobbied to change the law so that the secular courts will not issue a civil divorce until a Get has been given. (There are some fine details, but that's the basic idea.)
Many other options have been considered over the years; for instance, we could pull aside the groom five minutes after the wedding, ask him to write a Get, and then order the rabbi to deliver it to his wife whenever they're no longer happily together. But the best system, emotionally, is what the Torah describes -- if the marriage falls apart, then he does the right thing and gives her a Get.
Really one of the best options right now is the increased push for an agreement before the couple gets married; these create all sorts of strong incentives for him to give a Get when and if it is called for. Many rabbis have worked very hard on formulating these, defending them halachically, and pushing for them to be used. And if a woman asks for this before the wedding and her fiance refuses to sign it, that's a big warning sign and she should probably think again about marrying him. The most common one in the US is known as "The Beth Din of America prenup" (sometimes called "Rabbi Willig's prenup"); rabbis who belong to the Rabbinical Council of America are required to use one of these when performing a wedding. There's plenty of discussion about it on this website. So far, the BDA prenup has worked every time: if the couple signed one before getting married, then when they got divorced, he has given a Get. There are other forms of agreements, some intended specifically for Israel, as well; though I don't know a lot about their details.
Comment: Btw if the wife left with no halachik excuse the husband has no obligation to give her a get
Comment: Actually, the RCA members "can use a different prenuptial agreement" if they don't hold of the BDA prenup, which might be a totally pointless agreement ("I, groom, affirm I will give a Get when requested to. [Signature]"). Pretty stupid resolution by the RCA insisting people sign pointless documents just Lishmah. It seems like it's just there so people can claim the RCA requires halakhic prenups and confuse people into thinking they require the Halakhic Prenup (capital H capital P). It's quite disingenuous to say the least, though you seem to be using it as intended...
Comment: @hazoriz what is an example of a wife leaving "with no halachik excuse"?  and what is an example of a wife leaving with a halachik excuse"?
Comment: @ninamag https://www.sefaria.org/Shulchan_Arukh,_Even_HaEzer.77.2
Answer: see end of chapter 13 in rambam gittin
The last halacha below sums up the answer

7
  If an epidemic was raging throughout the world, and [a woman] says, "My husband died," her word is accepted. For [there is no widely accepted likelihood] with regard to a plague; everyone knows that in a time of plague some die and some live. And it is possible that strong young men will die from the plague, and elderly infirm people will be saved. And therefore, we do not suspect that she relied on the likelihood that most people died.
8
  It has already been stated that a witness who [did not see evidence of the person's death himself, but who] testifies after hearing the statements of another person is acceptable with regard to [the verification of the death of] a woman's [husband].
When does this apply? When the person heard a mentally competent adult - even a servant or a maid -servant - say that so and so died. If, however, a person heard from a mentally incompetent person or from a minor that an individual died, he may not testify [to that effect], nor do we rely on their statements.
9
  [There is an exception to the above principle.] If a person heard children saying: "We just came from so and so's funeral. These and these many people recited eulogies. The sage so and so and these and these others followed the bier. A nd this and this is what happened to the bier," the person may offer this as testimony [regarding a man's death], and on this basis permission is granted for [the deceased's] wife to remarry.
10
  When a Jew says, "I killed so and so," [the man's wife] is allowed to remarry on the basis of his testimony. [The rationale is] a person's own testimony cannot be used to incriminate him. [Therefore, he is not disqualified, and] he did testify that [the husband] died.
11
  It has already been stated that statements made by a gentile in the course of conversation can be used as a basis to grant [a woman] permission to remarry.
What is implied? If a gentile exclaimed: "How terrible is it that so and so died! He was so nice! He did so much for me!" Or if the gentile was talking and said, "We were traveling on our way, and to our amazement, so and so who was traveling with us fell down and died. We all were amazed that he died so suddenly." If he makes statements of this nature that indicate that he has no intention of giving testimony, his word is accepted.
12
  When a Jew hears a gentile [say] in the course of conversation [that a man died], he may testify that he heard these statements, and the man's wife may be granted permission to remarry on this basis.
When does the above apply? When there is no rationale to explain [why the gentile would make these statements if they were not true]. If, however, there could be a reason for the gentile's statements, and he is making them with another intent in mind [his word is not accepted].
For example, [a gentile] told a Jew, "Do such and such for me, or else I will kill you, as I killed so and so," he is not making these statements in the course of conversation, for his intent is to cast fear upon his listener.
13
  Similarly, if a person heard the gentile legal authorities say, "We executed so and so," their word is not accepted. For they will use falsehood to reinforce their position and to cast fear [among the populace]. The same applies in all similar instances.
14
  When, at first, a gentile made statements in the course of conversation, and afterwards was asked questions [by Jews] until all the details [of the person's death] were disclosed, his statements are accepted, and the woman is granted permission to remarry on this basis.
15
  It has already been stated that a witness who testifies: "I heard that so and so died," is acceptable with regard to testimony [concerning] a woman's [husband], and the woman may remarry on this basis. [This applies even when] he heard the statements from a woman or from a servant.
If, however, a witness, a woman or a servant says: "So and so died; I saw that he died," the witness should be asked: "What did you see? How do you know that he died? " If the witness responds with clear [testimony], his word is accepted. If the witness replies, describing a situation in which it is highly likely that the person would have died, we do not grant his wife license to remarry. For testimony concerning a man's death [can be accepted] only when [the witness can say] with certainty that he saw the man die, and there is no doubt concerning the matter.
16
  What is implied? If a man was seen falling into the sea, even if he fell into the ocean, testimony should not be offered that the man died, because it is possible that he was cast away or escaped [from the sea] from an [unseen] place.
If he fell into a body of water with definite boundaries - e.g., a cistern or a cavern in which a person standing [at the edge] could see the entire periphery - testimony that the man died may be offered, and license may be granted for his wife to remarry, provided [the witnesses] remained there for a period of time beyond which it was impossible for the man to live, and saw that he did not ascend [from the body of water].
Similarly, if he was cast into the sea and a net was cast in after him, and a limb that a person would not be able to live without was raised up, testimony may be offered that he died, and his wife may [be granted license] to remarry.
17
  If [a man] fell into a lair of lions, leopards or the like, testimony that he died may not be offered, for it is possible that they will not eat him. If he fell into a pit of snakes and scorpions, into a furnace, or into a boiling caldron filled with wine or oil, or his esophagus and windpipe were slit - either in their majority or in their entirety - testimony may be offered that he died, even if he arose and fled. For [in these situations], he ultimately will die.
Similar laws apply in all situations in which it is impossible that the person will live, but rather will die shortly afterwards. Testimony may be offered that he [died].
18
  If we see a man hanging and a vulture eating from his body, testimony may not be offered that he died. [This applies] even if he was stabbed with a lance, or arrows were shot at him.
If, however, we see the vulture eating from a place that would cause him to die - e.g., his brain, his heart or his intestines, one may offer testimony that he died.
19
  [The following laws apply when] one witness testifies, "I saw that he died in a war or in a landslide, or that he drowned in the ocean and died," or mentioned other causes that would probably lead to death. If he says, "I buried him," his statements are accepted, and she may be granted permission to remarry. If he did not say, "I buried him," she should not be granted permission to remarry. If, however, she remarries, she need not leave [her second husband].
20
  Similarly, if one witness testifies that a woman's husband drowned in the sea or in a body of water that does not have a defined periphery, he did not emerge [from the water], all traces of him have disappeared, and his existence has been forgotten, the woman should not [be granted license to] remarry on this basis, as we have explained.
If, however, she remarries, she need not be forced to leave her second husband. Even if a gentile said in the course of conversation, "So and so drowned at sea," and on this basis [the man's wife] remarried, she need not be forced to leave her second husband. Nevertheless, [in the above instances,] the sage who gave permission for her to remarry should be placed under a ban of ostracism.
21
  [The following rules apply when the body of a man who was] slain or died of natural causes is discovered. If his forehead, his nose and his facial features are intact, and his identity can be established based on them, testimony concerning his death may be offered.
If, however, any of these identifying factors is missing, even if there are signs [through which he can be identified] on his body and on his personal artifacts, even if one of those signs is a mole, testimony concerning his death should not be offered.
When does [the leniency mentioned in the first clause] apply? When the corpse was seen within three days of his murder or death. After three days have passed, testimony concerning his death should not be offered, because his facial features [may have] become distorted.
22
  [The following rules apply when a man] drowned at sea and was cast out onto dry land. Although several days have passed, if his facial features and his nose can be identified, testimony may be offered with regard to his [death], for in water the features of a corpse do not become distorted until an extremely long period of time has passed.
If the corpse lay on dry land for twelve hours after being cast out of the sea and the corpse became bloated, testimony may not be offered because [his features] have been distorted. When we look at the form [of a corpse] in order to identify [a man] to offer testimony with regard to his [death], [it is acceptable if] we look at [the corpse] even by candlelight or by moonlight.
23
  [The following rule applies when] we see a person at a distance and he says that he is so and so, the son of so and so, or so and so from a particular place, and that he has been bitten by a snake and is dying. Even if we go [to the place where he was standing], find [the corpse and discover] that its features have changed to the extent that it is no longer distinguishable, we may, nevertheless, [grant license for] his wife [to] remarry:
24
  [A person's testimony is effective in the following instance.] A person came and said: "A court - or people - told me, when you arrive at this and this place, tell them that Yitzchak, the son of Michael, died." When this person came to that place and delivered the message - although he is not aware of the identity [of the deceased] - since [the people at that place] do know his identity, [the deceased's] wife [may be granted] permission [to remarry]. We do not presume that perhaps it was another person named Yitzchak, the son of Michael, who died.
25
  When a Jew and a gentile left from our [location] for a different destination, and the gentile came and said in the course of conversation: "The man who left [this city] with me died," [the deceased's] wife [may be granted license to] remarry. [This applies] even when the gentile does not know the identity of the man, provided he says: "I buried him."
26
  Similarly, when ten men were taken together while shackled in chains or tied by heavy ropes used to lead camels or the like, from one place to another, and a gentile came and said in the course of conversation that all ten men who went out while tied died, and he buried them, their wives [may be granted license to] remarry.
27
  If a Jew says: "A Jewish man died in our company in this and this place. These and these were his facial features. These and these were signs of identification," we do not make a guess and say that it was probably so and so. Rather [the person is not considered to have died] until a witness mentions his name and the name of his city.
If, however, [a person] says: "One of the inhabitants of the city of so and so journeyed out in our company and died," we check in that city. If only one man left the city, his wife [may be given permission to] marry.
28
  [The following rule applies if] a document was found saying: "So and so, the son of so and so, died," or "So and so, the son of so and so, was killed": If it can be determined that this was written by a Jew, [the man's] wife [may be given permission to] marry.
Similarly, when a person has lost the power of speech, and he was tested, as he would be tested with regard to a get, and it is proven that he is mentally sound, if he writes that so and so died, we may rely on his writing, and [the deceased's] wife [may be given permission to] marry.
We do not follow the standard process of interrogation with regard to witnesses who testify [concerning the death of] a woman's [husband]. For our Sages did not speak about establishing stringencies regarding such matters. [Indeed, their approach was characterized by] leniency in order to permit a woman without a husband [to remarry].
29
  Do not wonder at the fact that our Sages discharged the prohibition [against a married woman], which is considered a very severe matter, on the basis of the testimony of a woman, a servant or a maidservant, statements made by a gentile in the course of conversation, a written statement or [testimony] that was not investigated by the ordinary process of interrogation, as we have explained.
  [These leniencies were instituted] because the Torah requires only testimony of two witnesses, and all the other details of the laws of witnesses with regard to matters that cannot be verified definitively except via witnesses and their testimony - e.g., that one person killed another, or that one person lent money to another. When, by contrast, the matter may be verified definitively without the testimony of a witness, and the witness cannot justify [his statements] if they are not true - e.g, when one testifies that a person died, the Torah did not necessitate [that the requirements of formal testimony be met in these instances]. For it is unlikely that a witness will testify falsely.
  For this reason, our Sages [extended] the leniency with regard to this matter and accepted the testimony of a single witness that is based on the testimony of a maidservant, [testimony] from a written document, and [testimony] that was not investigated by the ordinary process of interrogation. [These leniencies were accepted] so that the daughters of Israel will not be forced to remain unmarried.


Can a civilization subsist forever

Question: I watched this excellent video by Eugene Khutoryansky - https://www.youtube.com/watch?v=GOrWy_yNBvY a while back explaining why life in the universe must end. I don't want to believe this but it seems inevitable since life needs energy and once you fuse matter all the way to Iron, its very hard to get more of that. Lets say there is a master civilization that has made extraordinary strides in technology and can easily perform tasks like creating stars, transporting matter quickly between two points, etc. Is there a plausible scenario where such a civilization could be immortal? Could they have some sort of cycle going that allows them to subsist not for a very long time, but indefinitely?
Comment: [INSUFFICIENT DATA FOR MEANINGFUL ANSWER.](http://multivax.com/last_question.html)
Comment: this civilization for ever ??? let's hope better for the universe :)
Comment: Subsist or exist?
Answer: The short answer is that all processes will produce heat losses which are unrecoverable. There would be no way to fuel a civilization indefinitely, because only part of the energy input comes back as useful energy output; the rest radiates off into space.
Answer: Almost ... maybe ... for a very limited definition of forever.
Frank Tipler wrote a book titled The Physics of Immortality: Modern Cosmology, God and the Resurrection of the Dead.
I read the book when it was first printed. Long book, lots of equations and some pretty wild assumptions.
The basic idea is that computers get fast, AI becomes real, and we simulate all of the possible universes in a computer. Since the computer is so fast, reality inside the simulation passes very quickly, as in trillions times faster than out meat based existence (maybe even faster as the book never gave a limit that I recall). Also, the computer uses less and less energy to the point it can run all of the situations with consuming too much energy.
Tipler then also assumes a big crunch and the energy levels will rise. With the higher energy levels computers compute faster and faster with the higher energy levels kick in, allow more and more simulation.
Tipler also talks abound surviving the big crunch and setting the initial conditions for the next cycle. And oh yeah, we eventually become God, not just any God, but an infinite, omnipotent, omniscient being very similar to the Christian God.
Book is a serious snoozer. Generally physicists were pretty brutal in their reviews. But if you are ok with a simulated civilization, you can approximate infinity.
Of course, others might prefer the Heavenly civilization with the real triune godhead running the show eternally. Not some 2nd rate simulation you know.
Answer: I'm no scientist, but it seems to me that any investigation of how to survive after we've lost our current supply of usable energy, should at least glance at the related question, "where did the energy come from in the first place?".
Your extremely advanced technical society could probably find the answer to that question and apply that answer to creating more energy from where-ever our current supply came from.
Comment: https://www.youtube.com/watch?v=Dc-m9dumEaw - Lisa, in ths house we obey the laws of thermodynamics
Comment: @GaryWalker, +1 for a very funny and appropriate video!  But as a layman/non-scientist/neophyte-to-the-worship-of-thermodynamics, let me ask...  Where did the energy come from in the first place?  What is the established doctrine within the scriptures of science for why we  have energy here in the middle of time, when energy is absent both before the big-bang and after the heat death of the universe?  "It was created during the big bang" is a great answer... but how was it created?"  That is the question I think the OP's advanced society will be able to answer.
Comment: @HenryTaylor Energy is conserved. Its only usable energy that's decreasing.
Comment: @HenryTaylor - Where did the energy come from? There is no real scientific answer. There may never be. Reversing entropy is simply inconceivable at this time. Where did it all come from: no real scientific answer exists, though there are speculative answers like random vacuum flux, but where did the vacuum flux come from? Maybe a religious answer, God - not exactly something we could choose to reproduce. Some wonder where did God come from, others consider this a same/different type of question than where did the vacuum flux come from? You need something a lot better than WorldBuilding.
Comment: @GaryWalker, Which is why I brought it up.  To apply some perspective to the OP's question.  Rohit is asking if creativity and the application of science can ever defeat entropy, restoring heat loss energy to a usable form.  This is a fundamentally unanswerable question because we cannot predict how far science will advance from where we stand today.  I'm an optomist at heart, so the other provided answers seemed to fatalistic for me, and given that the OP Question also involves extremely deep time, I think optomism is practically mandatory.
Answer: If you're talking real civilizations, I'd say there's still a lot of questions whether a civilization can last forever.  It's actually a pretty long standing philosophy question, with some colorful commentaries such as Nietzsche's treatment of The Last Man in Thus Said Zarathustra.  There, the Last Man was a pocket of civilization which strived for nothing but immortality.  Nothing mattered except things which could extend their society forever.
Nietzsche had some strong words to say about that mentality.
Regardless, since this is world building, we can talk about some rather interesting contrived civilizations, and leave it to the physicists to fill in the details.  I am aware of at least one interesting approach to lasting forever which is thermodynamically consistent.  It doesn't reach up into the stars, however, trying desperately to find more and more energy.  Instead, it reaches inward.  Thermodynamics requires entropy to always increase in a closed system, but it does not specify how much it has to increase.  If you can find a way to create a system which sustains itself using an amount of energy proportional to the remaining energy in the system, then you can continue to progress using exponentially less and less energy.  You effectively need to concentrate the usable energy into smaller or more subtle structures as time progresses.
If you're looking at the ability to compute things, Laudauer's principle  indicates that the cost of changing a single bit is proportional to temperature, so in theory, if the temperature of the universe were to cool towards absolute zero, you may be able to stretch out your computation forever.
If you try to develop structures which are capable of this, you start to find "self awareness" to be very important.  Without it, it is remarkably hard to ration the amount of energy you spend properly.  Every fiber of your being needs to act in concert with every other fiber.
A tall task, but hey.  Welcome to world building!
Answer: Aparently ancient spiritual quantum knowledge says that what is always was. Meaning that if there is life, Life will always be and always was.
The Human mind is a bit limited in its scope and overstanding of existencial concepts based on misconceptions about life and death and therefore finds it perplexing to accept the eternalness of life and energy.
The answer is Yes. But as always we must define "Subsist" to be able to answer the question in detail. :)
Comment: Does this answer the question?

Can a civilization subsist forever