Does knowledge require consciousness?

Question: Does knowledge require consciousness for the entity that knows? In other words, is it the case that only conscious entities can know things? I was led to ask this question by considering whether or not the search engine Google knows things. It seems true to say that Google knows many facts, but does it really? After all, Google, or even the Internet more generally, does not (as far as we humans know!) have consciousness. So, my question is, can only conscious entities know things?
Comment: If one can *know* something without *intentionality* -- without *reflecting* on said knowledge -- then perhaps consciousness is optional.
Comment: On a related note, does knowledge exist when an external cue or trigger is required for recall? Language transformers such as [GPT-NeoX](https://www.eleuther.ai/projects/gpt-neox/) (third-party playground [available here](https://textsynth.com/playground.html)) can produce intelligent output based on a user-provided prompt. If such a prompt is necessary, is the output nevertheless an expression of knowledge?
Comment: Does this answer your question? [Do machine learning algorithms have knowledge (if not justified true beliefs)?](https://philosophy.stackexchange.com/questions/28268/do-machine-learning-algorithms-have-knowledge-if-not-justified-true-beliefs)
Comment: No. Knowledge is an object, and objects don't have needs. On the contrary, you, you need not only consciousness, but a number of other resources in order to get knowledge.
Answer: Obviously knowledge is more than data storing: An encyclopedia has no knowledge, but stores data.
I take the term "conscious" in your question in the sense of "self-conscious". Then an autonomous Mars rover has knowledge about his environment. Because it navigates on the basis of data it succesively acquires when moving around. But the Mars rover is not self-conscious because it does not consider itself from a metalevel.
I am undecided whether conscious (in the broad sense) processing of data is required for knowledge. I am curious to learn what others think about this point.
Summing up: Self-consciousness is not necessary for knowledge. Knowledge is more than data storing. Knowledge includes the capability to apply the stored data, e.g. for action.
Comment: What is the delineation for *metalevel*? If I focus on *myself*, I have self-awareness. If I focus on *others' thoughts*, I have theory of mind. If I focus on *others' thoughts of me*, have I self-consciousness?
Comment: @Michael Assume there are several levels of mental processes: One the basic level 1) I have sense perceptions, emotions, start a motor action etc. . On the higher level 2) I am aware of and discriminate the different acitivities from level 1). On the highest level I am self-conscious and register myself as a unit. Each higher level is a metalevel with respect to the lower levels.
Comment: +1 Would you accept that an encyclopedia stores knowledge, but has no knowledge of the knowledge it stores, particularly presuming knowledge is the use of information, that is contextualized data, to achieve goals?
Comment: @J D I accept that an encylopedia has no knowledge of the data stored in it, because an encyclopedia cannot process those data. But also Searle's Chinese room has no knowledge of the Chinese language - nevertheless it processes the input data. Hence goal orientation of the processing seems an important requirement for knowledge. The Mars rover acts goal oriented.
Comment: Technically any input-output function or mechanism has the *implicit* goal of satisfying its nature. A Chinese room may thus have a goal.
Answer: I would argue that an agent, even a non-conscious one, can be described as knowing things. We might say a Roomba knows how to clean the whole carpet. It doesn't know, how to cope with a suddenly opened door, and a world outside without walls.
The word 'consciousness' comes with a lot of baggage, as probably the single biggest source of dispute in modern philosophy. So I would suggest you need to look functionally at what is happening when information becomes knowledge.
I suggest that it is about organising the information so as to be useful, that is getting situated relationally to it. Discussed in more detail here: As humans, do we require a total understanding of information to fully embody it as knowledge? We can use Hofstadter's idea of strange-loops to understand there is something unusual that happens when an agent can include a model of itself in the process of situating - that this can result in deciding how to be (what kind of agent, for desired results), and so support ideas about having intentions (sets of ideas what agent to be, related to goals).
For Hofstadter, a strange-loop investigating self & world in multiple ways & using different approaches, can form a 'tangled hierarchy', which we can understand as the basis of the properties we associate with consciousness - an agent, that is situated in a meaning-cosmology that allows it to act intentionally.
Comment: The [roomba knows](https://www.bbc.com/news/uk-england-cambridgeshire-60084347) what to do in a world without walls.
Answer: Short Answer
Depends. Many philosophers recognize different types of knowledge. Gilbert Ryle, for instance, in his seminal work The Concept of Mind recognizes knowledge-how (SEP), for instance, which is commonly understood as a skill. It is possible, therefore, to have skills and not be consciously aware of them. According to a naturalized epistemology, many aspects of knowledge have been demonstrated to be subconscious.
Long Answer
The philosopher Robert Audi posited that one of prime sources of knowledge is consciousness, and certainly conscious knowledge-that is often held up as the quintessence of knowledge. Knowledge-that requires language skills and demonstrates self-reflection, and is the core content of what lies between the covers of philosophy texts. But there are situations where a philosopher is pressed to concede that consciousness knowledge-that isn't comprehensive.
Let's start with a sleepwalker. What should a philosopher make of the fact that a person who is in an altered state of consciousness might function to an uncanny degree as a conscious person? Somnambulists (Mayo Clinic) may engage in relatively complex behaviors:

Do routine activities, such as getting dressed, talking or eating
Leave the house
Drive a car
Engage in unusual behavior, such as urinating in a closet
Engage in sexual activity without awareness
Get injured, for example, by falling down the stairs or jumping out a window
Become violent during the period of brief confusion immediately after waking or, occasionally, during sleepwalking

I don't know about you, but driving a car while talking to someone in sleep seems to be a perfect case to demonstrate knowledge-how and knowledge-that are both possible with out consciousness. If a philosopher of mind pays attention to psychology, then it's rather certain that consciousness itself is but a very limited aspect of the human mind, and that intuition and habit are far more weighty in terms of human behavior. From abnormal psychology and its exotic cases that demonstrate brain irregularities, such as alien hand syndrome, dissociative identity disorder, and oddness as chronicled by Oliver Sacks in his The Man Who Mistook His Wife for a Hat that just what it means to be conscious and in control of one's body is somewhat malleable.
Journalist Malcolm Gladwell in his Blink: The Power of Thinking Without Thinking built a case of how intuitions sometimes are unknown or even opposed to conscious thought within the same person who is an expert at some forms of knowledge-how. He talked about how high performing athletes sometimes have conscious understandings of their bodies that are the opposite of how their bodies actually function, for instance. Thinking, Fast and Slow by Nobel-prize winning Daniel Kahneman also makes an excellent case for a model he expanded on which categorizes human knowledge into a fast, erroneous sort (Type I), and a deliberate, logical and linguistic sort (Type II).
Ultimately, the relationship between consciousness (SEP) and self-knowledge (SEP) are intertwined, and for the philosopher who embraces science, evolutionary epistemology (SEP) and other modern notions of epistemology promise to develop philosophical theses regarding knowledge along lines of empirical evidence. Philosophers will continue to split hairs over definitions, of course, but they stand to benefit from claims that have scientific certainty about the structure and behavior of the human brain and mind as well as language use. In this way, philosophers can appeal to physical facts to help continue with their taxonomy of knowledge and its sources.
Answer: Yes, knowledge requires consciousness. Attributing knowledge to a mechanical object like a Roomba is anthropomorphism--the unjustified assignment of human characteristics to things that are not human. The ancient form of anthropomorphism is often mocked today, but the idea that machines think or have knowledge is just the modern manifestation of this ancient error.
If you are conscious, then you have awareness, feelings, thoughts; there is something it is like to be you. No one else can really know what it is like to be you--not fully--but nevertheless there is such a thing. Knowledge is just an aspect of what it is like to be conscious. There is something that it is like to know something. For example, there is something that it is like to know that you are about to die, or about to get laid. It is an internal mental experience, and not merely an outward behavioral pattern.
So, although it is fine in practice to say that a Roomba "knows how to vacuum", you have to understand the statement "know" in that sentence as metaphorical. Because of the way your brain works, when you watch a Roomba, your brain tells you that there is a deliberate purpose there, guided by knowledge, but this is an illusion. The belief that the Roomba really, literally knows something is just as much of a mistake as thinking that a mirage is real; it is being fooled by an illusion.
There is nothing that it is like to be a Roomba. There is nothing that it is like to experience an obstacle like a Roomba. The Roomba operates as it does because of physical forces. It no more knows when it hits a wall than a branch knows when when a bird alights on it, yet the branch droops anyway. Nor does the branch know when the bird flies off, yet it springs up in response. The branch is merely responding to physical forces. The Roomba is nothing more than a very clever device designed to react to physical forces in a way that is useful for vacuuming carpets.
Answer: Depends on what we mean by knowledge.
An infant predator (say, a cheetah) isn't born with the instinct to look out for the weaker animals that are easier to pray upon. That's something that it learn from trial and error by watching its mother and role-playing with its siblings.
That's knowledge that is acquired, developed, honed. How much of that is intentional, we do not know, but it is certainly a form of knowledge.
This does not require consciousness (awareness of the self, or awareness that it is aware of said knowledge, or aware that it is aware that it is aware, recursively ad infinitum.)
So, knowledge in this sense does not require consciousness.
Answer: The quintessential aspect of knowledge is that it we identify patterns from the data we gather from the world, which help us to simplify our understanding of the world around us. Only sentient beings can gather and process data and extract information from it in order to determine any recognizable pattern in the chaos using their memory and tools. The former implies that only conscious beings can form memory and thus capable of deciphering order from chaos.
In the case of a universe with no beings, its impossible to ascertain, but I tend to gravitate towards "no knowledge in a universe with no beings" view, because knowledge inherently implies a "knower" who acquired information inferred from data and thus who "knows".
Comment: Machine learning excels at gathering data and identifying patterns, and is not sentient.

Does knowledge require consciousness?


Should the name of a piece of software be formatted as code?

Question: I've noticed that in posts & suggested edits the name of a piece of software is sometimes formatted as code, e.g. R or Stata. Why?, & should this new (to me) convention be encouraged or discouraged? (I'm not of course suggesting editing current posts either way just for this reason.)
Comment: I think it's basically pointless (though it does serve to highlight the package which may sometimes be slightly useful), but in any case not necessarily 'wrong'; to me it's more a matter of taste in formatting. I have seen a lot of proposed edits that do this, but I don't think it's an acceptable reason to suggest an edit (though if enough other good changes are made in the edit I'd generally let it go).
Comment: I have no idea if it *should*, however, I do it sometimes; it makes it more distinct. I don't necessarily advocate that anyone else do it, & I just as often don't myself. It's just random.
Answer: The peculiar use of a single letter to name software, as in C, J, S, and R, cries out for special formatting to help the reader.  Therefore I consistently write "R" instead of "R" and I appreciate posts that do this, too.  Some other packages do have conventional formatting: for instance, "Mathematica" is always italicized on the Mathematica site.
As far as edits go (picking up on a comment by @Glen_b), tastes differ, so during reviews I don't apply any particular convention.  I look for consistency in formatting.  I check that proposed edits to reformat text and code do not introduce any errors.  I follow guidelines laid down elsewhere suggesting we should eschew making minor edits, like formatting improvements, in posts that aren't very recent.  During reviews I therefore check that substantive edits are proposed and am grateful for any incidental formatting improvements made en passant.
Comment: Picking R or S for the software name could only happen in pre-Internet-search-engines age.
Comment: @StasK Yet still happens. Awhile ago I found myself searching "Anaconda Python" and got utterly useless results. Fortunately, that one at least seems to be fixed.
Answer: No, it is not code, and contrary to @Glenn_b I would argue that it is wrong to do so. Think about the semantics of the markup used; marking something as code that clearly isn't breaks the semantic meaning of the markup. That is bad!
What is wrong with just emphasising with bold or italics the name of a piece of software?
Comment: That's an excellent point about semantic markup. Like (almost) everyone else on SE, I have learned by watching and emulating. It quickly became clear that a single quote is not just code markup: it is frequently applied to certain software names like "`R`", to names of database fields, to code snippets, to pseudocode, and to code itself. On sites that do not support $\TeX$ it's necessary to co-opt code markup for writing more readable mathematical formulas. I have therefore inferred that a quote has, at best, only a vague semantic meaning. I may be wrong, but the damage is widespread.
Answer: My guess is that it justified in the sense of looking like the formatting that you will see in the tags under the question (which for better or worse looks exactly like the code formatting), thus ensuring some sort of uniformity within a page. I tend to like it, but, as Glen_b and whuber, definitely won't see this as a major reason for a proposed edit.
Comment: You can also use the tag markup `[tag:r]` for example which would render as [tag:r] (yuck, it renders differently in comments to posts - there it looks like the tags under the Qs). That may be better in instances when there is a reasonable number of pre-existing Q's here as it would link to a page showing Qs filtered by the tag. Better too if there is an appropriate tag-wiki entry. As I mentioned in my Answer, marking something up as code when it isn't code breaks the semantic web...


Linux #open-file limit

Question: we are facing a situation where a process gets stuck due to running out of open files limit. The global setting file-max was set extremely high (set in sysctl.conf) & per-user value also was set to a high value in /etc/security/limits.conf. Even ulimit -n reflects the per-user value when ran as that head-less user (process-owner). So the question is, does this change require system reboot (my understanding is it doesn't) ? Has anyone faced the similar problem ? I am running ubuntu lucid & the application is a java process. #of ephemeral port range too is high enough, & when checked during the issue, the process had opened #1024 (Note the default value) files (As reported by lsof).
Comment: You shouldn't need a reboot. Try (as root) ulimit -Hn 100000, ulimit -Sn 100000 and restart your project under the same shell. You might also want to check /proc/sys/fs/file-max.
Answer: One problem you might run into is that the fd_set used by select is limited to FD_SETSIZE, which is fixed at compile time (in this case of the JRE), and that is limited to 1024.
#define FD_SETSIZE      __FD_SETSIZE
/usr/include/bits/typesizes.h:#define   __FD_SETSIZE        1024

Luckily both the c library and the kernel can handle arbitrary sized fd_set, so, for a compiled C program, it is possible to raise that limit.
Comment: You should use something like epool for 1000+ files anyway. Maybe run with strace to see what system calls java is doing.
Answer: Considering you have edited file-max value in sysctl.conf and /etc/security/limits.conf correctly; then:
edit /etc/pam.d/login, adding the line:
session required /lib/security/pam_limits.so

and then do
#ulimit -n unlimited

Note that you may need to log out and back in again before the changes take effect.

Linux #open-file limit


Probability in multiple choice exams

Question:
A multiple choice exam has 175 questions.
Each question has 4 possible answers.
Only 1 answer out of the 4 possible answers is correct.
The pass rate for the exam is 70% (123 questions must be answered correctly).
We know 100 questions were answered correctly.
What is the probability of passing the exam, if one were to guess on the remaining 75 questions?
Answer: The number $X$ of correct answers in the remaining $75$ that were answered randomly, is binomially distributed with parameters $n=75$ and $p=0.25$, in symbols $$X \sim B(n=75, p=0.25)$$ The probability to pass the exam is equal to $$P(X\ge23)=\sum_{x=23}^{75}P(X=x)$$ Since it is difficult to calculate the above sum if you are not allowed to use a calculator or a program like excel, you can approximate $X$ with a normal random variable $Y$ such that $$Y \sim N(μ=np, σ^2=np(1-p)) \implies Y \sim N(μ=18.75, σ^2=14.065)$$ Now $$P(X\ge 23)=1-P(Y\le 22.5)$$ where we applied also the continuity correction.
Comment: You are welcome Brittany. No, I would suggest that you try to take it by yourself from here. Good luck....
Comment: Thanks Stefanos. Can you solve the equation as well to derive the answer?
Answer: We have already answered 100 questions, so there are only 75 questions left to answer.
Since we are guessing our way through the multiple choice questions, our probability of success in each question will be $\frac{1}{4}$
Since the pass mark is $\frac{123}{75}$, we need at least $\frac{23}{75}$ in the final 75 questions.
This is the same as saying that we need to find $P(X\ge23)$, i.e. "What is the probability of getting 23 or more questions correct?"
The information we have so far suggests that we can use the binomial distribution.
$X \sim B(n,p)$. Where $n=75$ and $p=\frac{1}{4}$ in your question.
However, we may have a slight problem.
75 is too large for us to use the $ncr$ formula and binomial tables don't generally include $n=75$. Unless you have a graphical calculator or some sort of statistical software, we will need to use a $normal \ approximation$ in order to answer your question.
When do you need to normally approximate?

Look at $np$ and $nq$. $\left(n=75 \ and \ p=\frac{1}{4} \right)$
Look at n, is it "Large"? ($n\ge30$ is normally a candidate).
if $n$p and $nq>5$ and $n$ is large, you can try a normal approximation.
Also, if $p$ is close to $\frac{1}{2}$, this is another indication.

$X \sim B \left(75,\frac{1}{4} \right)$
we are looking for $P(X\ge23)$
Normally approximating:
$Y \sim N(18.75,14.0625)$ as $Y \approx N(np,npq)$ is the normal approximation to $X \sim B(n,p)$ where $q=1-p$
Applying continuity correction, $P(X \le 22)$ becomes $P(Y \le 22.5)$
Normal distribution:   $Z = \frac{X-\mu}{\sigma}$
$Z= \frac{22.5-18.75}{\sqrt14.0625}$
We need to find $1-P(Z<1)$
Look for $\varPhi(1)$ on normal tables, the answer is $0.84134$.
Therefore, the normal approximation gives us an answer of $1-0.84134=0.15866$
The normally approximated answer to your question is $0.159(3dp)$.
Continuity correction:
$P(X\ge23)$ is the same as $1-P(X\le22)$
$P(X\le a)$ becomes $P(Y\le a+0.5)$ after the continuity correction.

Probability in multiple choice exams


Confusion Matrix vs AUC Confusion with Random Forest

Question: I'm currently training a random forest classifier with 1000 trees and am receiving the following confusion matrix. I've split the training set 75/25 against the test set but am not sure why I'm seeingf such a low True Negative score?  This is a binary classification problem and my dataset contains 88% of Class 0 whereas Class 1 represents 12% of the total content.  I've tried experimenting with class_weights but I have not been able to get the True Negative score above 6%. What am I missing as it seems to pass most tests including Cross-Validation > .90 etc.
Comment: You hardly beat the naive baseline of 88% accuracy. So your model is simply not very well suited for your problem or the data are just very hard to predict. However, with the given information it is impossible to say what could be done to improve the fit.
Answer: From your confusion matrix it actually looks like your class imbalance is over-favoring the positive class (90.04% to 9.96%). Because you have such an extreme class imbalance in your data your random forest is likely just classifying almost everything as positive class and calling it a day.
To solve this issue you need to either down-sample your larger class or up-sample your lesser class to reach closer to 50/50 split. Otherwise you will likely just end up with a classifier that grossly over-predicts the positive class.
When you are splitting your data you can also try stratifying by your label (so that the same proportion of positive to negative class exists in your training and testing sets).


Replacing timer switch for bathroom exhaust fan

Question: I am trying to replace the timer switch for my bathroom exhaust fan. I found plenty of options, all of which come with colour-coded wiring (white = neutral; black = hot; red = load; green = ground), as in the picture below. However, these colours do not match the original switch (photo #2). Also, the original wires coming out of the wall are super thin. From my research and (very) limited knowledge, I sense the original blue wire is a remote control wire. For clarity, I live in a condo/apartment, and my bathroom fan is connected to the fan coil/central air handler in my bedroom, which has an ON/OFF "ERV" switch that must be in the "ON" position for the bathroom fan to work. The original timer replacement part costs $125(!), so I am trying to go for another option. Any suggestions/ideas/input are welcome. Thanks!
Answer: The last photo is of a low voltage device, not mains voltage. The marking "remote timer switch" indicates that the actual timer switch is part of your air handler and this is simply a control panel.
Unless you want to do a lot of rewriting , I'm afraid you'll need to buy the original part.
Comment: Thank you so much for your time and for your input. Much appreciated. I have found this is, indeed, a low voltage - push button auxiliary/point-of-use control / timer switch for an Energy Recovery Ventilator (ERV) system, in this case for the bathroom exhaust fan. It seems every manufacturer has their own propietary timer :(
Answer: Well, we don't know what that proprietary switch is doing.  It might have complex electronics and be talking on CANbus.  Or it might just be a plain switch hiding in there that's just shunting 2 wires, and maybe the other 2 are for a backlight or something. We don't know.  If it was the latter, you'd be able to use any plain switch.  And the old-school spring-wound timer switches would work in that case.
It's not a case of "everything is proprietary and incompatible".  It's a case that yours is.  Generally there are 3 categories:

120V switching, using a plain "switch loop".  It will only support old school spring-wound timers and a few pushbutton ones made to work with no neutral.
120V switching, with neutral present.  That is what your fancypants pushbutton job is for, and it won't work on anything else.

These first two cover the vast majority of installations. However, they provide very little control.

A variety of proprietary systems that use low voltage for stuff - GE RR7, what you have here, all sorts of different setups with varying degrees of compatibility, and the necessity of doing some engineering to read the manual and use the products accordingly.

You have this system.  ERV's are awesome, and I wish more people would use it (instead of, say, non-ERV systems with a 12,000 watt makeup air heater LOL). But ERVs do not inherently need the fancy low-voltage control you are looking at.  It could just be a regular switch like a normal bathroom fan.
That low-voltage stuff is there to do something fancy.  I would consult the installer to understand why that was selected and what will be impacted if you defeat it.


Highlighting sentences in the statement of purpose

Question: I am under the impression that admissions officers are busy people and they have lots and lots of applications to review, especially in top schools. Because of this, it could happen that the some statements of purpose might not be thoroughly read.
Does it make sense to highlight things (underline, bold) that I think admissions officers are looking for? Like ranking or publications? What might admissions officers understand from the statement of purpose if they found these highlights?
Comment: Okay, for PhD applications, it's not the university admission officers you need to worry about, it's the professors in that department.  Highlighting a couple of key points should be fine.  Just be factual and not self-aggrandizing.  It will be interpreted as these are the things you're trying to highlight.
Comment: Perhaps you should clarify: e.g., are you applying to undergraduate institutions in the US?
Comment: Sorry. Applying for PhD in the US.
Answer: I use a similar approach, using bold to highlight key words or expressions in a short free text summary in my CV. The benefit is that points I think are key to my career are visible even at a glance. As you mention, many are stressed and reading through letters take time. Although the persons responsible for the admission process should read the material carefully, it is only human to, for example, get tired after a large number of applications. Using highlighting and other forms of structuring elements (paragraph breaks or even bulleted or numbered lists) to make the text easier to access is therefore a good way to make the reading easier.
To anyone thinking that highlighting might induce unfair advantages, it is worth stating that it can also easily back-fire if the highlighting is not consistent or give an impression that is not consistent with what the text or other supporting material will indicate. In other words, any highlighting must be done with care to be a tool to simplify the access to the information and not to skew it.
Depending on where you are in your career, the CV will be the most important part of an application. Finding ways in which to summarize, for example the general impact of your articles or other activities becomes important. This is why I have a short summary text at the start of the CV, the lists of publications is then supporting the statements about number of publications, the citations of individual articles, etc.


Can't install windows

Question: I try to boot from the Windows XP disc and it wont let me, it says there is no Harddrive, when i do have a hard drive. I just want to uninstall ubuntu and get windows.
Answer: Whilst installing Ubuntu the hard disk was formatted as Ext4, and windows does not recognise Ext4 or your hard disk.
You need to format the disk using a file system that windows recognises such as NTFS or FAT.
The simplest solution is to boot your computer using the Ubuntu live install disc,
 select Try Ubuntu,
and then use Disc Utility or Gparted to format the hard disc as NTFS or FAT.
Once that is done windows will recognise the disc and allow you to install windows XP.

Can't install windows


More impressive way of saying "I am really interested in your works" to a Prof

Question: I want to send an email to a professor in London. I wanna say "I'm really interested n your works" but I am searching for a more impressive and more British way of saying that. Could any one help me?
Comment: Avoid asking for help writing (or proofreading). "How should I write this?", "is this correct?", and "which is correct?" questions are out of scope and your question may be removed. See: "[What topics can I ask about here? - Help Center](/help/on-topic)". If there is an unstated specific concern, such as "What does (word) mean in context?" or "How does (grammar or punctuation rule) apply in context?" ask that question instead. Also check out "[Where can I ask for free proofreading? – Meta](https://english.meta.stackexchange.com/questions/7571)"
Answer: You could write something like:

Dear Professor Surname,
I was enthralled and impressed by your remarkable and groundbreaking work on the tubular endothrums of reticulate worms.

But here's my advice: don't.
I don't know where you are from, but I have seen many students from countries such as India write emails to British scientists which are much too floral and seem positively cringeworthy to the usually casual British ear. The professor you are writing to is unlikely to want to see you bow and scrape, and will be unimpressed by extravagant language use. Instead they want to know why you find it interesting and what it is you are writing to them for. A clear, concise email is much more likely to get a positive response than one which goes for "impressive" language.
So instead write something like this:

Dear Professor Surname,
I am writing to you to express my interest in your advertised project 'sexual signalling in retriculate worms'.
While studying for my Masters degree at the University of Place, I came across your 2016 paper "Rethinking the endothrum". I was particularly interested in your idea that rather than being involved solely in immune resistance, endothrums are used as a device for sexual signalling. This was exciting for me because during my research project on non-reticulate worms.... (etc.)

Which shows you've read their work, explains why you're interested in it, and links it to your work and/or background. I've arbitrarily assumed that you're a student looking for a position, but if you're interested in collaboration or just in discussing their ideas the same applies. Put your efforts into explaining why they should spend their time on you, not on tarting up your language.
Comment: @Dan Bron: It struck me that this question (and the answer) belongs squarely to https://interpersonal.stackexchange.com/ or maybe academia.SE, but in either case, the culturally cued response seems good to me.
Comment: I usually downvote answers to questions like this in order that people get discouraged from answering such questions, and lacking answers, people get discouraged from asking such questions in the first place. But this is such solid advice, I'll recuse myself from this thread. Well done.
Comment: Great answer ... but I'm not sure I'll ever be able to put a worm on a hook again when I next go fishing, after reading this.
Comment: I'd give this two upvotes if I could!


Hide errors from users but show to admin?

Question: Under 'Error messages to display' I can hide errors (as is recommended for production sites). However is it possible to hide errors for everyone except a certain role?
Comment: yes it is, there are some modules around for that. But what you are suggesting also hides form errors too, as I stated below.
Comment: Feature request here https://www.drupal.org/node/2743119
Answer: Preface: This answer was first posted as an answer to "How do I suppress a warning or error message for site users?".
Disable Messages module
You could use the Disable Messages module for this. Here is a quote from its project page:

Gives a site owner options to disable specific messages shown to end users. The core drupal message system as offered by drupal_set_message is an excellent way for modules to send out messages to the end users. However not all drupal site owners are keen to show all the messages sent out by drupal core and all modules to their users. This module gives site administrators a reasonably powerful way to filter out messages shown to the end users.

Some of its features are:

Filter out messages that match a full text string exactly.
Filter out messages that match a regular expression.
Permissions to specifically hide all messages of a given type from any role.
Disable all filtering for specific users.
Disable all filtering for specific paths.
Apply filtering only for specific paths.
Debug system to get messages in the HTML without showing it to the end users.

Available for either Drupal 6, Drupal 7 or Drupal 8.
About using regular expressions
If you're using its 'regular expression' feature, you have to make sure that you use a regular expression that "catches" the error message you want to intercept, as explained also in the Community documentation.
Below "Tip: Keep it simple." on that page, there is a great sample, which looks like so:

Be aware that something that appears very straightforward like:

Notice: Undefined index: field_txt_student_id in ctools_entity_form_field_content_type_render() (line 96 of [...]entity_form_field.inc).

Has a lot more unseen characters in it than one might expect:

Notice: Undefined index: field_txt_student_id in ctools_entity_form_field_content_type_render() (line 96 of [...]entity_form_field.inc).

So just wrap the meat of the grep with a simple "any character" regex: ".+" as in:

.+Notice.+Undefined index:.+ctools_entity_form_field_content_type_render.+entity_form_field.inc.+

So the "clue" to come up with a correct message, is to shrink the error message you want to catch, and putting ".+" characters where appropriate.
Talking about shrinking, note that the field_txt_student_id has been omitted in the regular expression also (to make it NOT depend on the field name).
Example
As another example, assume you want to catch this error message:

PDOException: in dblog_watchdog() (line 160 of /home/dbuser/public_html/yoursitesname.com/modules/dblog/dblog.module).

In this case a possible regular expression should look something like so:
.+PDOException.+in dblog_watchdog().+(line 160 of.+/modules/dblog/dblog.module).+

Note how I intentionally did not include part of the path before /modules/dblog/dblog.module (so that it can be reused in another site where the very same error occurs ...).
Also note that you have to give it some thought to yes or no include the 160 part of it: if the module ever changes a bit so that in the error message it (eg) becomes line 161, your error will not be intercepted anymore. To avoid that, omit the 160 part of it, if that's what you prefer (personally I would rather first see the error coming back then, and then re-adapt my regular expression).
If your regular expression doesn't work at first (= the message still appears), then it might be because there is some typo in the regular expression. To pinpoint such typo, first try with a less restrictive regular expression, even if it was only to try with something like so (to catch ALL messages containing PDOException and dblog_watchdog):
.+PDOException.+dblog_watchdog.+

Or even like so (to catch ALL messages containing PDOException):
.+PDOException.+

These last 2 expressions would probably suppress way too much messages, so you'd want to narrow it down to that single one you're after.
Unstable alternative
There is also the Better Messages module as an alternative. However, for D7 (which is what this question is about), it only has an Alfa version.
Answer: You can check the user role by using the in_array() function.
In your template:

<?php global $user; ?>
<?php if (!in_array('YOUR_ROLE', $user->roles)): ?>
  <?php if ($messages): ?>

      <?php print $messages; ?>

  <?php endif; ?>
<?php endif; ?>

Or you can do it in your preprocess function (not sure is the message variable is called correctly but it can give you an idea)

function MYTHEME_preprocess_page(&$variables, $hook) {
  global $user;
  if (!in_array('YOUR_ROLE', $user->roles)){
    // This has to be checked, could be something similar.
    unset($variables['page']['content']['messages']);
  }
}

Comment: You're right, you could try to find out how the error messages differ from default messages and create a hook_permission for it. Good luck!
Comment: My understanding is that I cant hide  from users as it shows erros that users need to see as well as database type errors, eg if you try to create a node and leave out a mandatory field. Thanks
Answer: To remove notice from a Drupal website please follow below steps:

Go to admin/config/development/logging.
You have three choices:

None will disable all error reporting.
Errors and warnings will display on the most serious problems.
All messages will display all problems and is probably only useful for developers.

Another way to disable notice and error message through code. Add following code to the settings.php file:
$conf['error_level']=0;

You can also configure Drupal to only log the errors following these instructions: go to Administration > Configuration > Development > Logging and errors or go directly to the path /admin/config/development/logging and set "Error messages to display" to none. Drupal then still logs errors but doesn't display them to users.
If you require more control use the Disable Messages module.
Comment: This is about drupal_set_message, not error messages.
Comment: @njp - they all wander into $messages. Check your templates.
Comment: In Drupal 8+ settings.php it's `$config['system.logging']['error_level'] = 'hide';`
Answer: Actually this is not really doable.
You can hide all messages for users or roles but the main problem lies in the way drupal categorizes errors.
A form error is the same as a database exception for the messages function, so if you hide errors you also hide the error messages of a comment form.
I would love for someone to prove me wrong because I have not managed to achieve hiding php notices but showing form notices at the same time.
Answer: You can use the better message module. It offers role based configuratoin and/or regular expression matching to filter out some notifications.
Comment: Better messages does not have a role based configuration for showing messages, only for showing the modules type of messages
Answer: You may  to comment this code in your theme
<?php if ($messages): ?>

      <?php print $messages; ?>

  <?php endif; ?>

or status_messages theme element serves this you may write own theme function in template.php
MYTHEME_status_messages(&$variables){}

This could effect only to notice and warning errors
Comment: But if `$messages` section is commented it will not display for admins too.
Comment: My understanding is that I cant hide  from users as it shows erros that users need to see as well as database type errors, eg if you try to create a node and leave out a mandatory field. Thanks
Comment: http://api.drupal.org/api/drupal/includes!theme.inc/function/theme_status_messages/7 here is how core prepares a warning messages for rendering you may copy this logic and add your own logic in mythemename_status_messages() in your themes template.php file


Poincaré Conjecture and the Shape of the Universe

Question: Has the solution of the Poincaré Conjecture helped science to figure out the shape of the universe?
Comment: My impression is that all this "shape of the universe" stuff is mostly media hype.  As a rule, you shouldn't believe whatever nonspecialists tell you about a specialized subject.
Comment: I voted up this question, only because I expect I'll want to crib a good answer at the next party I attend, when someone asks me what I do.
Comment: At first sight, this looks like a question that is not suited for MO, but in light of the great answers below, I guess not.
Comment: There is this guestion's positive answer in next research paper.
http://arxiv.org/abs/1303.2673.pdf Division-Alebra/Poncare-Conjecture-correspondence
Comment: Related. http://physics.stackexchange.com/questions/1787/what-is-known-about-the-topological-structure-of-spacetime
Answer: In Einstein's theory of General Relativity, the universe is a 4-manifold that might well be fibered by 3-dimensional time slices.  If a particular spacetime that doesn't have such a fibration, then it is difficult to construct a causal model of the laws of physics within it.  (Even if you don't see an a priori argument for causality, without it, it is difficult to construct enough solutions to make meaningful predictions.)  There isn't usually a geometrically distinguished fibration, but if you have enough symmetry or even local symmetry, the symmetry can select one.  An approximate symmetry can also be enough for an approximately canonical fibration.  Once you have all of that, the topology of spacelike slices of the universe is not at all a naive or risible question, at least not until you see more physics that might demote the question.  The narrower question of whether the Poincaré Conjecture is relevant is more wishful and you could call it naive, but let's take the question of relating 3-manifold topology in general to cosmology.
The cosmic microwave background, discovered in the 1964 by Penzias and Wilson, shows that the universe is very nearly isotropic at our location.  (The deviation is of order $10^{-5}$ and it was only announced in 1992 after 2 years of data from the COBE telescope.) If you accept the Copernican principle that Earth isn't at a special point in space, it means that there is an approximately canonical fibration by time slices, and that the universe, at least approximately and locally, has one of the three isotropic Thurston geometries, $E^3$, $S^3$, or $H^3$.  The Penzias-Wilson result makes it a really good question to ask whether the universe is a 3-manifold with some isotropic geometry and some fundamental group.  I have heard of the early discussion of this question was so naive that some astronomers only talked about a 3-torus.  They figured that if there were other choices from topology, they could think about them later.  Notice that already, the Poincaré conjecture would have been more relevant to cosmology if it had been false!
The topologist who has done the most work on the question is Jeff Weeks.  He coauthored a respected paper in cosmology and wrote an interesting article in the AMS Notices that promoted the Poincaré dodecahedral space as a possible topology for the universe.  But after he wrote that article...
There indeed is other physics that does demote the 3-manifold question, and that is inflationary cosmology.  The inflation theory posits that the truthful quantum field theory has a vaguely stable high-energy phase, which has such high energy density that the solution to the GR equations looks completely different.  In the inflationary solution, hot regions of the universe expand by a factor of $e$ in something like $10^{-36}$ seconds.  The different variations of the model posit anywhere from 60 to thousands of factors of $e$, or "$e$-folds".  Patches of the hot universe also cool down, including the one that we live in.  In fact every spot is constantly cooling down, but cooling is still overwhelmed by expansion.  Instead of tacitly accepting certain observed features of the visible universe, for instance that it is approximately isotropic, inflation explains them.  It also predicts that the visible universe is approximately flat and non-repeating, because macroscopic curvature and topology have been stretched into oblivion, and that observable anisotropies are stretch marks from the expansion.  The stretch marks would have certain characteristic statistics in order to fit inflation.  On the other hand, in the inflationary hot soup that we would never see directly, the rationale for canonical time slices is gone, and the universe would be some 4-manifold or even some fractal or quantum generalization of a 4-manifold.
The number of $e$-folds is not known and even the inflaton field (the sector of quantum field theory that governed inflation) is not known, but most or all models of inflation predict the same basic features.  And the news from the successor to COBE, called WMAP, is that the visible universe is flat to 2% or so, and the anistropy statistically matches stretch marks.  There is not enough to distinguish most of the models of inflation.  There is not enough to establish inflation in the same sense that the germ theory of disease or the the heliocentric theory are established.  What is true is that inflation has made experimental predictions that have been confirmed.
After all that news, the old idea that the universe is a visibly periodic 3-manifold is considered a long shot.  WMAP didn't see any obvious periodicity, even though Weeks et al were optimistic based on its first year of data.  But I was told by a cosmologist that periodicity should still be taken seriously as an alternative cosmological model, if possibly as a devil's advocate.  A theory is incomplete science if it is both hard to prove, and if every alternative is laughed out of the room.  In arguing for inflation, cosmologists would also like to have something to argue against.  In the opinion of the cosmologist that I talked to some years ago, the model of a 3-manifold with a fundamental group, developed by Weeks et al, is as good at that as any proposal.

José makes the important point that, in testing whether the universe has a visible fundamental group, you wouldn't necessarily look for direct periodicity represented by non-contractible geodesics.  Instead, you could use harmonic analysis, using a suitable available Laplace operator, and this is what used by Luminet, Weeks, Riazuelo, Lehoucq and Uzan.  I also that I have not heard of any direct use of homotopy of paths in astronomy, but actually the direct geometry of geodesics does sometimes play an important role.  For instance, look closely at this photograph of galaxy cluster Abell 1689.  You can see that there is a strong gravitational lens just left of the center, between the telescope and the dimmer, slivered galaxies.  Maybe no analysis of the cosmic microwave background would be geometry-only, but geometry would modify the apparent texture of the background, and I think that that is part of the argument from the data that the visible universe is approximately flat.  Who is to say whether a hypothetical periodicity would be seen with geodesics, harmonic expansion, or in some other way.
Part of Gromov's point seems fair.  I think it is true that you can always expand the scale of proposed periodicity to say that you haven't yet seen it, or that the data only just starts to show it.  Before they saw anisotropy with COBE, that kept getting pushed back too.  The deeper problem is that the 3-manifold topology of the universe does not address as many issues in cosmology, either theoretical or experimental, as inflation theory does.
Comment: @Greg -- Now you remind me of my AP English teacher, Dr. Phillips.  He was also brilliant, widely learned (once in class he digressed to talk about Russell and Whitehead's _Principia Mathematica_) and so creative that, if you didn't have anything better to say, it was sometimes a reasonable strategy to write an essay suggesting connections between things when you yourself could not see them: he could, and would, often fill in the details to make your thesis look reasonable and sound.  But of course it doesn't mean that you knew what you were talking about, only that he really did.
Comment: Just to be clear, it is not the original question that I find risible but rather DARPA's challenge.  It reminds me of an episode of NUMBERS where the premise was that a mathematician who had claimed to solve the Riemann Hypothesis was being extorted by criminals who wanted to exploit fast factorization algorithms.  What can you do as an engineer with the Geometrization _Theorem_ that you couldn't do with the Geometrization _Conjecture_?
Comment: That is a very flattering compliment!  I am not sure how much I deserve it, but thank you.  Certainly in the case of condensed matter physics, my answer is not so creative.  I have been working in quantum computation, and in that area everyone knows about the connection between anyons and quantum link invariants.  See for instance http://arxiv.org/abs/0704.2241 .  Benjamin Mann at DARPA might well have heard about this work, or possibly not.
Comment: I don't want to knock DARPA too much for trying to do good, but I have to agree that their list is a strange imitation of Hilbert's list of 23 problems.  For one thing, the list asks for the cosmological implications of the smooth Poincare conjecture in *four* dimensions, not the Poincare conjecture solved by Perelman. http://www.math.utk.edu/~vasili/refs/darpa07.MathChallenges.html
Comment: Also, Pete, the question you quoted could be a reference to something legitimate:  Quantum link invariants at a root of unity such as the Jones polynomial seem to be a valid model for the quantum state of certain 2-dimensional condensed matter systems.  Still, the question as stated is a grandiose variation that does not even mention quantum invariants.
Answer: No, I believe it has not and that it is hard to see how it could be directly useful.
Just for starters, it is not clear whether the universe is simply connected.  It is not even clear that this is a meaningful question.  In this regard I cannot resist quoting a passage from Steven Krantz' Mathematical Apocrypha Redux:

Mikhael Gromov tells of attending lectures about cosmology by
two topologists -- really great topologists -- concerning the possible shape
of the Universe. Gromov asked the first of these whether the Universe was
simply connected. The man replied, "It is clear that the Universe cannot be
but simply connected, for non-simple connectedness would imply some
high-scale periodicity, which is ridiculous." The other topologist gave a
talk entitled "Is the Universe simply connected?" which seemed to be related to the question. When informed of the first speaker's statement, he said,
"Who cares, it's still a meaningful question, like it or not."
In discussing these divergent opinions, Gromov offers his own: "Take a
loop in the Universe, a reasonably short loop compared to the size of the
Universe, say of no more than $10^{10}$ to $10^{12}$ light years long and ask if it is
contractible. And, to be realistic, we pick a certain time, for example $10^{30}$
years, and ask if it is contractible within this time. So you are allowed to
move the loop around, say at the speed of light, and try to determine
whether or not it can be contracted within this time. The point is, even
imagining our space to be some topological 3-sphere S3, we can organize an
innocuous enough metric on S3 so that it takes more than $10^{30}$ years to contract certain loops in this sphere and in the course of contraction we need to
stretch the loop to something like $10^{30}$ light years in size. So, if $10^{30}$ years is all the time you have, you conclude that the loop is not contractible and whether or not $\pi_1(S^3) = 0$ becomes a matter of opinion."

On the other hand, the issue of applicability of Poincare (and geometrization) to the real world has been raised by others.  The government agency DARPA listed the following as one of its 23 Challenges for the Future:

What are the Physical Consequences of Perelman's Proof of Thurston's Geometrization Theorem? Can profound theoretical advances in understanding three dimensions be applied to construct and manipulate structures across scales to fabricate novel materials?

To me DARPA's question seems naive bordering on risible, but others may feel differently, especially if they receive funding.
Comment: You're not the only one to have that reaction to the DARPA challenges.  There was a thread about them at the _n_-Category Cafe, where the majority feeling was that they were a disgrace: http://golem.ph.utexas.edu/category/2007/12/challenges_for_the_future.html
Answer: With all due respect to Mikhail Gromov, Physics is not about homotoping loops in the spatial universe!  That would certainly be risible.  In Physics, the fundamental group reflects itself in the spectrum of the laplacian: $S^3$ and $S^3/\Gamma$, say, have different harmonics and this is something that can be infered from measurements, even if perhaps not measured directly.
According to current cosmological models, the early universe was a hot plasma which light could not escape: basically photons had a very small mean free path because there is so much activity in the plasma that they find something to scatter against before long.  It is only after the universe starts cooling that at some point the photons can escape.  This happens over a period of time, but cosmologically speaking we can assume it happens instantaneously.  The cosmic microwave background we measure today are the photons which were released at that time. They have of course cooled down considerably since then.  They contain information about the "surface of last scatter" and what experiments such as COBE, WMAP, Planck,... are essentially doing is taking pictures of the surface of last scatter with increasing resolution.  The colours in the pretty pictures you see coming from COBE and WMAP correspond to temperature fluctuations which can be mapped to density fluctuations in the early universe via something called the Sachs-Wolfe effect.  In a nutshell, this effect relates the harmonic expansion of the density fluctuations in the early spatial universe and the harmonic expansion of the temperature as a function on the celestial sphere.  The latter can be measured directly, and the former can be inferred.  So in principle it is possible to relate the topology of the spatial universe to empirical data.
In fact the work of Luminet, Weeks, Riazuelo, Lehoucq and Uzan that Greg Kuperberg links to in his answer was based on the analysis of the first-year data from WMAP.  The power spectrum of the data revealed that the lowest lying modes were severely attenuated and this suggested that the spatial universe was missing the lowest lying harmonics: recall that the harmonics in $X/\Gamma$ are the $\Gamma$-invariant harmonics on $X$.  Of the possible models, it was $S^3/E_8$ which fit the (very scant!) data best.  This model has now been deprecated because it predicts the existence of "circles in the sky": sectors of circles in two different locations of the celestial sphere with the same temperature fluctuations.  There are computer algorithms that search for those circles in the sky but as far as I know none were ever found.
This story suggests the question: Can one hear the shape of the universe?, paraphrasing Mark Kac's famous question about the shape of a drum.  In the case of Kac's question we know the answer to be negative: Milnor found that there are non-isometric isospectral 16-dimensional tori, coincidentally the two tori which define the two heterotic string theories, and more recently also non-isometric planar domains with piecewise linear boundaries have been constructed which are isospectral.  However for three-dimensional space forms the answer to the question is positive, and this is gives hope that cosmological data might determine the shape of universe.
Whether the Poincaré conjecture has any bearing on this story is not clear to me, but what is undeniable is that the nature of the topology and the geometry of the spatial universe is physically relevant.  It bears upon such "big" questions as whether the universe is finite or infinite and indeed as to what its ultimate fate might be, whether or not Gromov or indeed any of us, will be there to witness it.
Comment: Again, I think my use of "risible" was not interpreted as I had intended; I edited my post in an attempt at clarification.

To me, Gromov's remark (as reported by Krantz; the title of his book contains, after all, the word _apocrypha_) emphasizes that a lot of assumptions have to be made in order for the question of simply connectedness of the universe to make good sense.  (For instance, why is it reasonable to assume that the universe, as a Riemannian manifold, is a space form?)  I don't wish to deny that there is deep and interesting mathematics and physics here.
Comment: That the large scale structure of the spatial universe looks like a space form follows from two properties: isotropy and homogeneity.  Isotropy is something that can be empirically tested.  Penzias and Wilson measured the cosmic microwave background and noticed that it is isotropic to a large degree.  I think that temperature fluctuations (divided by temperature) are of the order of $10^{-4}$ or thereabouts.  Homogeneity, on the other hand, is an assumption: usually paraphrased as the principle of mediocrity.  As usual, at the end it's always Occam's razor.
Comment: I had a thought which Ian Agol's answer confirmed: if you're already assuming that your manifold is a space-form, what do you need the Poincare Conjecture for?  Thus I think again that the answer to the poster's precise question has got to be "no".
Comment: The answer might indeed well be "no".  My point is simply that the topology of the universe is not "a matter of opinion", since it can be tested empirically.
Answer: The short answer is no. The fact is that experimental cosmologists use a very crude global model for the universe, the FLRW universe. The 3-dimensional cross sections of this
model are constant curvature 3-manifolds, and therefore already satisfy the Geometrization
Theorem. So in some sense cosmologists have already been taking the Poincare conjecture as a working hypothesis all along.
Comment: Where exactly is it that FLRW uses the geometrisation conjecture?  CMB + mediocrity gives you that you are on a space form.  That the model is crude is not in question: but it gets the right large scale structure and you can try to model the small anisotropies by perturbations.  This is hardly controversial.
Answer: No, as far as anyone can tell.
On the other hand, lots of people think about what the universe would be like if it were in fact the Poincaré dodecahedral space (the counterexample to the original Poincaré conjecture!).
See for example Dodecahedral space topology as an explanation for weak wide-angle temperature correlations in the cosmic microwave background in Nature, and The residual gravity acceleration effect in the Poincaré dodecahedral space available on the arxiv.
Further The optimal phase of the generalised Poincare dodecahedral space hypothesis implied by the spatial cross-correlation function of the WMAP sky maps claims to find some statistical evidence that this might even be true, by looking at correlations in the cosmic microwave background.
Answer: To me, one needs to look for an answer from the other end: Big Bang.
If the Universe was born from a single 1-connected point and all the following expansion has no singularities, i.e. can be considered as homeomorphic transformation, then the Universe has no reason to become n-connected.
Some confirmation of this is covered in the article ARXIV:1306.0533 by Maldacena and Susskind.
PS. So, one has to know connectivity of the "seed" of the Universe only, because generally, physicists have good reason to "believe" that all physical processes are homeomorphic transformations.
/humble physicist/
Comment: *If the Universe was born from a single 1-connected point and all the following expansion has no singularities, i.e. can be considered as homeomorphic transformation, then the Universe has no reason to become n-connected.* Singularities in GR do not have a well-defined geometry, topology, or dimensionality, and they are not point-sets, so it doesn't make sense to talk about the big bang as "a single 1-connected point." Your description of the conditions for the topology to remain unchanged also doesn't sound right to me. See http://arxiv.org/abs/gr-qc/9406053 .
Comment: It doen't mean that GR must be standard.
Comment: I did not assume that. However, intuitively I see that homeomorphic transformation should preserve all conservation laws - energy, momentum, space, rotation etc.
Comment: The Maldacena-Susskind paper appears to have nothing to do with what you're saying. It's about a cosmology containing an Einstein-Rosen bridge. It's also about quantum gravity, not classical gravity.
Comment: I belong to high energy physics and, therefore, you can consider me as a vulgar mathematician. However, want to ask two questions: did we have 1) quantum mechanics and 2) black holes at the state of T=0 (BigBang) ?
Comment: Ben, Takahiro - slowly I got into this subject and agree with your points. Black hole singularity violates homeomorphism. Connection between black holes and quantum mechanics becomes more interesting if to consider virtual black holes pointed out by Hawking: https://en.m.wikipedia.org/wiki/Virtual_black_hole


Is a thing a property of space and time?

Question: For example, there are sayings like "this house is better than yesterday" or "yesterday was so snowy." Are a thing and spacetime separate things or is a thing a property of spacetime?
Comment: How is the title question related to the phrases in quotes? There could be a theory that matter is a mode of spacetime in some sense, but that is not a common view and even that would not make it its "property" exactly.
Comment: "Are a thing and spacetime separate things...?" Better: "Are a thing and spacetime separate objects/entities...?"
Answer: One perspective is substantival dualism, according to which objects are distinct from space time. Material objects occupy regions of space time.
Another is supersubstantivalism, according to which objects are identical with space time.
Stanford Encyclopedia of Philosophy provides discussion of both. (See 4.5 for supersubstantivalism).
Here is an Argument Against Dualism, but it also provides perspectives of both arguments.
There appears to be no consensus.
Answer: Your question is largely generic. Most philosophical texts provide precise definitions of thing, object, entity, system, related to the matter of discussion, so you might find different, and even contradictory answers.
Here are some common definitions:

object is something that is not the observer (subject);
entity is used in an ontological sense (so, an object that exists in some context);
thing is usually something related to space and time, or also a natural entity;
system is a set of interrelated parts (objects), that is, existing in virtue of its parts, and in virtue of its relations.

So, for your question, the answer is no. A thing is not a property of spacetime, like an electron is not a property of an atom. Things would occupy space and time, according to the previous definition. In such case, a thing is not a property of spacetime, is not a separate entity. It just extends through space and time.
For Immanuel Kant, space and time don't exist in nature, but in our heads, we kind of create them in order to approach nature.
Comment: Thing is traditionally understood as an object of (sensual) experience. Your definitions appear to be rather arbitrary and not exactly common, to be honest
Comment: Precisely, as stated.


If $p > 5$ is a prime number, then the last digit of $p^4-1$ is $0$.

Question: If $p > 5$ is a prime number, then the last digit of $p^4-1$ is $0$ (ex.: $7^4-1=2400$).
How do I prove this?
Answer: By noting that the last digit of the fourth powers of $1$, $3$, $7$ and $9$ is $1$ and that the last digit of every prime number $p> 5$ is $1$, $3$, $7$ or $9$.
More formally, $p=i\pmod{10}$ with $i$ in $\{1,3,7,9\}$ hence $p^4=i^4\pmod{10}$. Since every $i$ in $\{1,3,7,9\}$ is such that $i^4=1\pmod{10}$, this yields $p^4=1\pmod{10}$.
Answer: Use Fermat's Little Theorem and note that if the last digit of $x$ is $0$, then $x \mod 10 =0$.
Or do what Did suggests, that's also good.
Answer: If ${p^4}$ is ending on $1$, then ${p^4} - 1$ will end on $0$. Hence we need to show that for all $p > 5,\,\,\,{p^4} \equiv 1\,(\bmod \,10)$. According to Euler theorem if $p$ and $10$ are relatively prime the congruence ${p^{\varphi (10)}} = {p^4} \equiv 1\,(\bmod \,10)$ holds. Any primes greater than $5$ will always be coprime with $10$. This shows that for all $p > 5,\,\,\,{p^4} - 1 \equiv 0\,(\bmod \,10)$ is true.
Answer: For $p>5$, prime numbers can have a one's digit of $1,3,7$ or $9$. Now consider the multiplicative group $\Bbb{Z}_{10}^{\times}= \{1,3,7,9 \}$. The group has order $4$, meaning for any $x \in \Bbb{Z}_{10}^{\times}$, we know $x^4$ mod $10 \equiv 1$. By filling in a couple gaps, this should be enough to make your argument.
Answer: By Fermat theorem
$$p^4\equiv1\pmod{5}\\p^4-1\equiv0\pmod{5}\\p^4\equiv1\pmod{2}\\p^4-1\equiv0\pmod{2}\\p^4-1\equiv0\pmod{10}$$
Since $p$ is odd so is $p^4$  clearly it gives $1$ as remainder by $2$.Also since $2$ and $5$ are co-prime we have that $0$ is remainder of $2\cdot 5$ which gives that the last digit is $0$
Answer: Just to note an alternative way through.
If $p\gt 5$ we have $(p,10)=1$
By Fermat-Euler, and noting that $\varphi(10)=4$, we have that if $(p,10)=1$ then $p^4\equiv 1 \mod 10$


Finite State Machine

Question: I tried to write a Verilog code for the finite state machine whose diagram shown below. I see nothing as an output. What is the wrong part of my code? or Is my code completely absurd?
My code:
module FSM(D1,D2, NextState);
input D1,D2;
output [1:0] NextState;
reg [1:0] CurrentState=2'b00;
reg [1:0] NextStateOut;
parameter S0=2'b00, S1=2'b10, S2=2'b11, S3=2'b01;

always @(D1 or D2)
 begin
 case(CurrentState)
 S0:
 begin
    if(D1==1'b0 && D2==1'b0)
        NextStateOut <=S0;
    if(D1==1'b1 && D2==1'b0)
    begin
        NextStateOut <=S1;
    end
end
S1:
begin
    if(D1==1'b0 && D2==1'b0)
    begin
        NextStateOut <=S0;
    end
    if(D1==1'b1 && D2==1'b0)
        NextStateOut <=S1;
    if(D1==1'b1 && D2==1'b1)
    begin
        NextStateOut <=S2;
    end
end
S2:
begin
    if(D1==1'b1 && D2==1'b0)
    begin
        NextStateOut <=S1;
    end
    if(D1==1'b1 && D2==1'b1)
        NextStateOut <=S2;
    if(D1==1'b0 && D2==1'b1)
    begin
        NextStateOut <=S3;
    end
end
S3:
begin
    if(D1==1'b1 && D2==1'b1)
    begin
        NextStateOut <=S2;
                end
    if(D1==1'b0 && D2==1'b1)
        NextStateOut <=S2;
    if(D1==1'b0 && D2==1'b0)
    begin
        NextStateOut <=2'b00;
    end
end
endcase
CurrentState<= NextStateOut;
end
assign  NextState= NextStateOut;
endmodule

State diagram:
Answer: An FSM typically has 2 always blocks: 1 sequential (with a clock), 1 combinational (no clock).  Assuming you have a clock and an asynchronous reset (untested):
module FSM(D1,D2, NextState, clk, rst);
input D1,D2,clk,rst;
output [1:0] NextState;
reg [1:0] CurrentState;
reg [1:0] NextStateOut;
parameter S0=2'b00, S1=2'b10, S2=2'b11, S3=2'b01;

always @(posedge clk or posedge rst) begin
    if (rst) begin
        CurrentState <= S0;
    end else begin
        CurrentState <= NextStateOut;
    end
end

always @*
 begin
 case(CurrentState)
 S0:
 begin
    if(D1==1'b0 && D2==1'b0)
        NextStateOut =S0;
    if(D1==1'b1 && D2==1'b0)
    begin
        NextStateOut =S1;
    end
end
S1:
begin
    if(D1==1'b0 && D2==1'b0)
    begin
        NextStateOut =S0;
    end
    if(D1==1'b1 && D2==1'b0)
        NextStateOut =S1;
    if(D1==1'b1 && D2==1'b1)
    begin
        NextStateOut =S2;
    end
end
S2:
begin
    if(D1==1'b1 && D2==1'b0)
    begin
        NextStateOut =S1;
    end
    if(D1==1'b1 && D2==1'b1)
        NextStateOut =S2;
    if(D1==1'b0 && D2==1'b1)
    begin
        NextStateOut =S3;
    end
end
S3:
begin
    if(D1==1'b1 && D2==1'b1)
    begin
        NextStateOut =S2;
                end
    if(D1==1'b0 && D2==1'b1)
        NextStateOut =S2;
    if(D1==1'b0 && D2==1'b0)
    begin
        NextStateOut =S0;
    end
end
endcase
end

assign  NextState= NextStateOut;

endmodule

Some modifications:

Combo always block uses @*
Use blocking assignments (=) in combo block
Use S0 parameter instead of 2'b00 in last assignment.

Note: @* is the same as @(potentially long list), but it is less error-prone. There is no need to maintain the list. For example, your list should include CurrentState, but it does not. @* does. Refer to IEEE Std 1800-2012, section 18.104.22.168 Implicit event_expression list.
Comment: You could also make `NextState` an `output reg` and eliminate the need for a separate signal (`NestStateOut`)

Finite State Machine


Omniauth+Devise+Facebook = An error occurred. Please try again later

Question: I followed these instructions verbatim: https://github.com/plataformatec/devise/wiki/OmniAuth:-Overview
config/initializers/devise.rb:
require "omniauth-facebook"
config.omniauth :facebook, "xxx", "yyy", :scope => 'email,offline_access,read_stream', :display => 'popup'

The View link works and it asks me to Sign In with Facebook. However, when clicking it, I get "An error occurred. Please try again later.". No other information or errors.
In my facebook app, 'app domain' is not set, and site URL is set to 'localhost:3000'.
My gut is telling me there is something wrong with that configuration/callback, however localhost:3000/users/auth/facebook/callback works fine.
Thanks in advance!
EDIT: When I try the login while logged in to the Facebook account that owns the app, it works perfectly. When I try with a different Facebook account, this error fires.
EDIT 2: Figured it out http://cl.ly/D6st
Answer: Go to your facebook application's settings set sandboxto disable
Thats all.


Why does the current in MOSFET have a quadratic function (explain logically without using the integration method)?

Question: The current equation relating Vds ,Vgs and Vt is already known to us ,but if there is any way we can find out how it varies quadratically without using the formulae?
Comment: Are you asking for an intuitive approach from first principles physics that should tell you why? No equations, just a reason why you must find that kind of result? (For example, it is easy to show that angular momentum conservation must arrive from a simple consideration of the geometry of space.)
Answer: In an enhancement mode MOSFET, voltage applied to the gate terminal increases the conductivity of the device.
Logically, think of it in terms of the conduction gap being closed with applied gate -source voltage as a 1/r² effect as the electric field is increased so on a log scale it might look like a linear slope.

Nanowire FET By Saumitra R Mehrotra & Gerhard Klimeck, modified by Zephyris - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=11299479


I'm creating a bitcoin wallet but I can't figure out how to send transactions with a low fee

Question: I created a bitcoin wallet https://github.com/Grantrocks/bitcoingadgets. After 2 days of constant errors, I got it to send btc. But I can't seem to get it to send btc somewhat fast at a low fee.
I use the module bit for transactions so I hope that there is nothing wrong with it, but if there is, I will gladly swap it out for a new module so the fees are lower.
So does anyone have a better method?
Comment: By "fast" do you mean receive confirmations quickly?
Comment: just realitvely. I dont want them to take around 2-3 hours to get 1 confirmation
Answer: A transaction paying a low feerate is equivalent to signaling low urgency.
Miners select transactions in a way that maximizes the revenue for their block. This results in the queue of unconfirmed transactions generally being processed in order of the feerate of the transactions. Therefore, the way to get quick confirmations is to pay an appropriate feerate.
You may however be able reduce the overall fees paid by using more inputs when sending at lower feerates, and using fewer inputs when sending at higher feerates.
If your question was about how to figure out the lowest feerate to get confirmed in a time-frame, you could perhaps still improve your feerate estimates. Alternatively, you could consider investigating replace-by-fee and implement your sending procedure such that you increase your transaction's feerate automatically over time if the transaction hasn't confirmed yet. To do this in the most thrifty way possible, you'd need to have a live view of the current mempool, though, but you could perhaps just revisit every 15 minutes and increase it by 1 sat/vB while it's not confirmed yet. If you start at the minRelayTxFeeRate of 1 sat/vB, that would get you to 13 sat/vB in three hours, which should get you confirmed usually in the current mempool weather. Note that frequent RBF'ing has privacy implications.
Answer: Confirming quickly, and low fees, are kind of mutually exclusive concepts. Miners will prioritize transactions that pay them a high feerate. If the feerate on your transactions is too low, then miners will prefer transactions that pay more than yours. If there are more than one block's worth of the transactions that pay a feerate higher than yours, then your transaction will not be included in the next block.
As such, you need to pay a higher feerate if you want your transaction to be confirmed quickly.
Comment: As I said in my answer, you can't have both fast confirmations and low feerate. It is how the Bitcoin network works, not anything that you can do from a wallet. You cannot guarantee that your wallet will make transactions that confirm quickly and also pay low fees.
Comment: Yes i know that the faster its confirmed the more it costs but i need to find a way to make it so this module has lower fees and the same confirm rate. Is there a free api or module that you know of that allows this?


How to subscribe a specific instance within an elastic beanstalk application to an SNS topic?

Question: Ok, so I have an elastic beanstalk application with a scalable web tier, served behind an ELB. Long story short, I need to be able to subscribe a specific instance within my web tier to an SNS topic. Is it safe for me to use a standard method to get the instance ip address (as detailed in python here How can I get the IP address of eth0 in Python?) and then simply subscribe to an SNS topic using that ip as an http subscriber?

Why? Good question...
My datamodel is made up of lots of objects many of which can have an attached set of users which may want to be able to observe those objects. This web tier in my application is responsible for handling the socket interface (using socket.io) for client applications.
When a user is created in the system, so too is an SNS topic for the user, allowing notifications to be pushed to that user when an object it is interested in changes. The way I am planning to set this up, a client application will connect to EB via socket.io at which point the server instance it connected to will subscribe to that user's SNS topic. Then when an interesting object changes, notifications will be posted to the associated user's topics, thus notifying the server instance that the client application has an open connection to, which can then send a message down the socket.
I believe it is important that the specific instance is subscribed rather than the web tier's external CNAME or ip, as the client application is connected to a specific instance and so only that instance can send messages over it's socket. Subscribing the load balancer would be no good as the notification may be delivered to an instance that the user is not connected to.
I believe the question at the top is all I need, but I'm open to creative solutions if my reasoning seems flawed??
Answer: Just incase anyone gets stuck down this same rabbit hole... The solution was to use Redis pub/sub rather than SNS and SQS.


Visitor's Page for Account Profile

Question: Just an idea for an Account Profile. If one visits another's profile page, he/she may leave a comment on the profile page. It may be thankful words or general comments about this user. I think it would be a motivation for a user to have a high quality answers to receive positive feedbacks. Please let me know what you think too. Cheers.
Comment: Orkut/LinkedIn have feature like this ... btw who care about profile viewes
Answer: No, Stack Overflow is not a social network. It is a site for questions and their answers, and not so much about the people that post those questions and answers.
I receive positive feedback for my answers by people voting on them. Sometimes they even leave a comment on specific answers. That is plenty of encouragement, and keeps the focus on the answers themselves!
Comment: +1. In addition, that would add one more place for spammers to spam, trolls to troll, and stalkers to harass. That is both more work for the moderators and can potentially be a source of discouragement for a victim of one of the aforementioned things.
Comment: See also this related question, where a PM system was declined for some of the same reasons: http://meta.stackexchange.com/questions/431/any-way-to-send-a-personal-message-to-another-user

Visitor's Page for Account Profile


How can I connect a skeleton to a mesh?

Question: How can I connect the skeleton to the mesh. I can refresh my memory on how to create the basic skeleton (but if you can explain it in more begginer terms, that would be much appreciated).
Comment: As it stands this question is too broad for the format of this site and would be better suited for a  forum format like [Blender Artists](https://blenderartists.org).Generic answer is: **Go to [Youtube and start following a beginner tutorial](https://www.google.com/search?tbm=vid&q=blender%20beginner)**. What do you want to do with Blender, animation, games, comics, 2D Art? Sci-Fi, Fantasy, Cartoon? Find one that suits your particular taste
Comment: @DuarteFarrajotaRamos. I apologize for how broad my question is. I was overwhelmed by the program :P A more specific question how to connect the skeleton to the mesh. I can refresh my memory on how to create the basic skeleton (but if you can explain it in more begginer terms, that would be much appreciated).
Answer: Although this is a very broad question you have to understand blender (pun intended i guess by the one who picked the name) is a composition of many different sub programs such as shading systems, particle effects, basic 3d modeling, lighting, and such. As you start to look for online tutorials and stuff I suggest you focus on learning one school of thought at a time. Just learn all the ins and outs of basic 3d modeling and playing with the meshes in different ways and the keyboard command shortcuts to copy, rotate, and any other direct interaction with your 3d meshes before you venture into key frames (animating 3d mesh) or shading. Once you feel comfortable with that then you move to something like lighting and then some.
A mistake many make, including me is that we all tried to dip our fingers into everything at once and going back and forth between the different aspects of blender can actually slow the learning process. Once you focus on a specific aspect of blender you"ll get more specific questions, which then you can ask here. Once you learn to ask the right things you'll find the blender community to be one of the most supportive and wonderful.

How can I connect a skeleton to a mesh?


What are these striped artifacts in these photos?

Question: I was at a concert and some of the pictures I took had these blue and red or black stripe artifacts, is there a name for these? Would I be able to make a similar or same effect if I desired or are these uncontrollable?  The pictures were taken on an iPhone 8.
Answer: A concert means rapidly changing, extreme light conditions. It looks like the conditions changed between metering and taking the picture. E.g. in the 2nd picture, the pink light came on and blew out the darker areas. I will base my answer on that assumption.
The phone then tries to recover by extreme post-processing. We cannot really know it's algorithms, but a few bits of color data need to cover the whole dynamic range. We get a few shades of green instead of hundreds. You can see that best in the "rings" around the green lights in the 1st picture, then outward several darker rings until black is reached.
The blue channel is probably not as much overexposed as the green one, so we can stretch blue and green differently - and get some shades of cyan in the process. You can get similar results with extreme highlight or shadow compression in RawTherapee or other programs.
The purple and blue lines appear at the border to the region illuminated by the blue lights. Again, there are only a few bits effectively available for each color, so you can't get the smooth transition you would rather like.
The fog is complicating things. There might have been more or less fog in a specific area, throwing shadows or reflecting more light.
Answer: The image defect can be described as posterization and results from aggressive colour correction which most modern cameras apply to obtain normal colours in common use case scenarios. You might get same problem even with large expensive cameras even though to a lesser extent. Modern cameras are tuned to produce good colour in common use cases (sunlight, incadescent lighting, natural dies) but will fail miserably when exposed to mix of saturated colours and gradients.
However, this defect can be easily dealt or at least significantly mitigated using negative exposure correction, highlight recovery, saturation adjustment (you can probably do that even in your smartphone) and tone curves. You might try different smartphone camera software and you might try taking raw photos and developing them yourself, that would stretch your abilities to deal with this quite a lot.


Handling browser-specific support of HTML input type="date"

Question: I am aware that the HTML 5 input tag, when used with type="date", needs to be fed an RFC 3339 full date as described here. Lots of questions here, such as this one, mention this.
However, browser support for the date type input tag varies a lot. For example, Safari on iOS 7 uses a nice date picker on which you can flip up and down to select day, month and year separately. Internet Explorer 10, on the other hand, does not handle date type input tags in any special way, treating them as plain text input tags.
When we put these two facts together, we find the following. If I feed the date type input tag on my page a properly-formatted RFC 3339 full date, as expected, it displays it nicely in browsers that have special support for it, such as Safari on iOS 7. However, the input tag shows an ugly and user-unfriendly yyyy-mm-dd date on browsers that don't handle it in any special way, such as Internet Explorer 10. I can't afford to show yyyy-mm-dd dates to my users, so I thought that I would rather feed my input tags user-friendly formatted dates, such as dd/MMM/yyyy (that's the format we use over here). But then, this works OK on browsers that handle it as simple text, like Internet Explorer; on Safari on iOS 7, which expects a proper RFC 3339 full date, the date type input tag appears blank.
So I am stuck. I guess I need a way to manually handle browse support individually, and programmatically format my dates according to what browser the client is using. My questions are these:

Do I really need to do that, or is there a workaround?
If I need to do that, can you please suggest a simple approach? I am using ASP.NET, C# and Bootstrap 3.

I would rather avoid introducing additional frameworks such as modernizr just to solve this problem. I can always go back to using plain text tags if this is too difficult or cumbersome to fix.
Thank you.
Answer: See this. It recommends 2 polyfills. This one and this one. Both look pretty good. Doing browser detection then special formatting is messy, so I don't recommend it.
Comment: Thank you. I've read through the documentation and it seems that I would need to include additional frameworks in my web app, something that I would rather avoid. I'll explore other options first. Thanks anyway.


how to increase my blog traffic?

Question: hi Im a newbie and I have been assigned a task for improving traffic to my company blog posts. how can I gain traffic through refferal traffic and improve my position in SERP. and also how to frame keywords for these blogs. give suggestions
Answer: The question is very generic and it can't be answered in a short post.
I would recommend you to learn basics of SEO.
You may consider these broad options:

Build quality content on your website and blog.
Share those blog posts on social media, particularly Google Plus.
If your content will be well researched and unique to your readers then you may wish to run some social media campaign to bring more readers to your blog.

These steps may not be enough but it will build the foundation and once you will learn about SEO you can start some planning and implementation for backlink which will help you greatly to get better ranking.

how to increase my blog traffic?


CartoDB - Update column from local csv

Question: So I uploaded a csv from my local drive and set up the map, but I would like to update a column of data every day and re-upload the csv, but keep map settings.
The dataset is very simple: one column for country names and one with values.  Only the values change every day, not the country names
Any ideas?
Answer: You have two different approaches here:

Using Sync tables with your local file being synchronized from a Dropbox/GDrive folder. Countries will be automatically georeferenced each time.
Using an automatic script in your end that updates your table with the new information via the SQL API: http://docs.cartodb.com/cartodb-platform/sql-api.html
Answer: You can sync your data with Google Drive or Dropbox. Here is a tutorial about it.
For doing that, you need a John Snow account (at least).

CartoDB - Update column from local csv


Finding the cryptographic hashing algorithm, given the plain text and the corresponding salted hash

Question: I have a salted hash (say about, 110 characters long) and the corresponding plain text that I used for hashing. As the title says, is it possible to do find the algorithm via crypt-analysis? What is the recommended approach, if it exists?
Comment: Can you give some background? Is this a practical problem that you have?
Comment: You can bruteforce
Comment: There's really not enough information to answer the question.  Can you give an example hash and plaintext?
Answer: Yes and no.
Yes. If by cryptographic hashing algorithm you mean (an unkeyed version of) one of the well known ones, then you can simply try all of them. There's not too many of them.
No. If by cryptographic hashing algorithm you mean just any such algo, then no. There are infinitely many of these.
(And you can trivially generate new hashing algorithms, simply by turning one of the unkeyed hashes into a keyed variant by plugging that hash and a random key into the HMAC construction for example. They will then behave like a completely new hashing algorithm.)


Can a professor make your final pass or fail?

Question: I current have an 85% in his class but my final is pass or fail. I'm horrible at math and have really tried my hardest to get that b but my professors math final is either you pass it or if you fail it, you fail the course! Is allowed? I also asked around and it seems he's the only professor that is doing this.
Comment: What did it say in the syllabus at the beginning of the semester?
Comment: In general, professors have quite a bit of leeway in how they design exams. How much depends on your institution's policies, which we don't know.
Comment: To expand upon @ff524's comment: I've had a several of math classes where 70% or more of one's grade was based on the final exam. While not an explicit "fail the exam, fail the course", if you god a score of, say, 50% on the final, you were likely to fail the course just because of how the percentages broke down. The Syllabus will often list the total grading percentages for the course.
Comment: One time I took an extraordinarily difficult math class and failed (perhaps 20% passed). Several of my colleagues took the course with different professors, and their returned midterms and finals were significantly easier. Some professors run really hard classes, and it is kind of their prerogative. For a course with a lot of sections it is definitely smart to ask classmates or even use various professor rating sites. Professors rarely have really high ratings, but the truly terrible ratings are significant. Look at the syllabus on day one, you can usually change classes still!
Answer: Why wouldn't it be allowed?

Legally? You didn't say what country you are in, but I'm not aware of any country that regulates courses at this level.
Your university's rules? You didn't say what university you are in, so it's impossible to say for sure. In general, though, the "instructor of record" has the authority to make decisions about how a course will be graded.

Broadly speaking, this does not seem like a bizarre policy that some wacko professor implemented; I've actually seen this in other math departments. I guess the philosophy is that most entry-level math courses are about skills: they do not want to pass you onto more advanced courses unless you know these foundational skills well enough to do them in a measurable way. (I realize that you may not personally plan to take more advanced courses, but the principle is the same).
Anyway: yes, unless your university has a policy that forbids it (e.g., a policy saying that all professors of a given course have to grade the same way), this policy is almost certainly allowed.
Answer: Since you asked your question so general (without specifying a country), I can also answer: yes, they can. In my country, for example, lecture courses are to be graded by only one single final exam.
It may be that this is not the case in your institution and that your professor is not allowed to grade in this way.
Note, however, that many professors do weird things while nobidy cares. (I had a professor who openly annoced that women should not be allowed to study and all women failed his course, it was widely known, but nobody cared. This is of course an abosolutely horrible and extreme example - I also had other professors who went over the rules and nobody cared.)
So what I advise you is: Don't just ask "around", but ask specific people who know these kind of issues are are sympathethic to you. For example, your student's union or your academic advisor. Those people should know if this grading is allowed, and, if no, if it is possible in your institution to do something against it.


How to add on a site page a button allowing to upload a folder (and not files individually) to a document library?

Question: I am designing a SharePoint site for a team so we can share documentation with external users. I wish to add a button on the homepage for the colleagues who will upload documentation with me. Once the upload is done, a flow with power automate analyze the information and parse it in several document libraries - and this part is OK for the moment. I would just need to add this button, so I am sure the folder they upload goes to right library. I have done a lot of research on the topic, but cannot find any help - especially since I want to upload a folder and not files.
Answer: See if the below solution meets your requirement.

Add an app named File Uploader by Virto from SharePoint Store to your SharePoint site.

Find it in Site Contents library and click it to run the app.

Cpoy the url of upcoming page.

Add a Button web part on your home page, edit the web part and paste the url you copied above into Link.

Test on my end.

Hope this may help.


Lending to the bank

Question: I would like to know how to enter an agreement with a bank to accrue interest in exchange for 'borrowing' my funds overnight. Anyone familiar with the process?
Comment: Sure.  Become a bank (or a national government) with enough money for them to care about, and they'll willingly borrow tens of millions of dollars from you.  But if you have tens of millions of dollars, you won't be asking this from **Personal**Finance.SE.
Comment: Move your funds to an interest-bearing savings account that pays more than the overnight borrowing rate.
Answer: This will happen automatically when you open an interest-bearing account with a bank.
You didn't think that banks just kept all that cash in a vault somewhere, did you?  That's not the way modern banking works.
Today (and for a long, long time) banks will keep only a small fraction of their deposits on hand (called the "reserve") to fund daily withdrawals and other operations.  The rest they routinely lend out to other customers, which is how they pay for their operations (someone has to pay all those tellers, branch managers, loan officers) and pay interest on your deposits, as well as a profit for their owners (it's not a charity service).  The fees charged for loan origination, as well as the difference between the loan interest rate and the deposit rate, make up the profit.
Banks rarely hold their own loans.  Instead, they will sell the loans in portfolios to investors, sometimes retaining servicing rights (they continue to collect the payments and pass them on) and sometimes not (the payments are now due to someone else).  This allows them to make more loans.
Banks may sometimes not have enough capital on hand.  In this case, they can make inter-bank loans to meet their short-term needs.  In some cases, they'll take those loans from a government central bank.  In the US, this is "The Fed", or the Federal Reserve Bank.
In the US, back around the late 1920's, and again in the 1980's some banks experienced a "run", or a situation where people lost confidence in the bank and wanted to withdraw their money.  This caused the bank to have insufficient funds to support the withdrawals, so not everyone got their money.  People panicked, and others wanted to take their money out, which caused the situation to snowball.  This is how many banks failed.  (In the '80s, it was savings-and-loans that failed - still a kind of "bank".)  Today, we have the FDIC (Federal Deposit Insurance Corporation) to protect depositors.  In the crashes in the early 2000's, many banks closed up one night and opened the next in a conservatorship, and then were literally doing business as a new bank without depositors (necessarily) even knowing.  This protected the consumers.  The bank (as a company) and its owners were not protected.
Answer: The easiest way would be to set up a common savings account. Most of them pay some meager interest rate, and over one night it would be especially meager.
A Certificate of Deposit is another way, but you'd have to lock the funds in for an extended period of time.
Comment: Would a money market account also count?
Comment: @Nosrac - ANY interest-bearing account is likely to fall into this category.  This includes savings accounts, CDs, interest-bearing checking, and so on.  The way banks get the money to pay interest is by lending money to charge (more) interest.

Lending to the bank


How to analyze analog output waveform in Modelsim

Question: I want to analyze an output sine signal from my VHDL code in Modelsim. I have created a project and simulated the code. However the outout in the "Wave" window is in binary form represented as a 32 bit output. I tried to change my signal as a Analog signal in wave properties but nothing really changed. I would like to se an analog output signal in decimal format which resemples a sine wave. How do I do this?
Comment: Modelsim can display analog waveforms, oscilloscope style, as well as digital signals. They might have to be integer or real, or numeric_std.signed or unsigned.
Comment: @BrianDrummond, my answer felt wrong when I typed it! Thanks and corrected below.
Answer: Yes, you can. On the Wave window, select your signals and right-click Under 'Format', select 'Analog' to see your signal as an analogue wave.
If you have a lot of data, you could write VHDL to write your values data into an output file in .CSV format (Comma-Separated Values). Then you could import that .CSV file into Excel and plot a graph from it.