Do American citizens have the right to prevent a president from taking the oath of office?

Question: As Americans, do we have the right and/or duty to prevent an individual from taking the Oath of Office to become the president if they strongly oppose that individual?
Comment: Yes. By voting a better candidate.
Comment: If it's any consolation, the Founders understood the fact that politics would attract the power-hungry and they were keenly aware of how people in power could shift the dynamic toward tyranny and despotism.  As such, they carefully designed a system of checks and balances to keep the power struggles mostly contained and, above all, played out in a way that avoids bloodshed.  The system isn't perfect, but it works toward minimizing the harm our leaders can do.  Some of the more cynical might even say that all candidates are unfit, by virtue of human nature.  Thus the Constitution.
Comment: Remember, if Trump is deemed unfit the Presidency passes to Pence.
Comment: @EthanBierlein - your original edit was perfect. "significantly changing the tone" of the question from opinionated rant to a balanced question is what editing is for, and the former shouldn't be on the site. I wish more people put in the effort to clean up existing questions instead of just criticizing, please don't let someone's opinion dissuade you from willing to do a beneficial and necessary cleanup.
Comment: Somebody may be able to demonstrate that Trump was not born in the USA. Has he shown his birth certificate? He certainly hasn't shown his tax returns. Might he be a Moslem or a Communist in disguise? Has he committed high crimes and misdemeanours? I feel sure there are endless possible reasons why he could be deemed unfit to take office. You just need to identify them.
Comment: @Ethan Bierlein, I would suggest that editing out the word 'unfit' significantly changes the tone of the question.  Perhaps its use reflects a personal opinion about a specific individual in this case, but the question hinges on the perception of an individual being unfit, even ignoring its possible application to current events.
Comment: @DanBryant Noted. I wasn't sure on the policy for opinionated questions here, so I'll edit it back in, if necessary.
Comment: I think we need to know what Ores means by "prevent"
Comment: [*Trump is from Pakistan, says Pakistani news channel*](http://www.indiatimes.com/news/world/trump-is-from-pakistan-says-pak-news-channel-265236.html) ;-)
Comment: @gerrit - only after they are sworn in.  Before that, we'd have something of an Electoral College or Constitutional Crisis. I'd say that my response is irrelevant because we'll certainly never find out, but I'm reluctant to talk about things that are almost certain never to happen, given what happened over the past 18 months.
Answer: The legal right? No.
The moral right and duty? That depends on your personal morals and ethics.

I urge you to remember though, half of your countrymen think that the candidate that won is fit to hold office, and democratically voted for them, twice (nomination and election).
Many of them consider your candidate to be unfit to hold office.
Consider if you want to live in a society where it is OK to overthrow the results of a democratic election.
Comment: Trump received 14,010,177 votes in the primaries, or 44.9% of votes cast, and 60,371,193 votes in the General Election, or 47.28% of votes cast.  Assuming all who voted for him in the primaries also voted for him in the general election, **4.31%** of the population voted for him in the primaries and **18.59%** in the general election.  It is not accurate to state that half voted for him twice.
Answer: Yes we do.  It's called being civically responsible by being informed, engaged and participating by speaking about the issues, and, most importantly, voting.
Our usual voting rate is around 50% for presidential races, and in this election I heard we had 18 million less votes cast than in the previous cycle.  NOTE: Brythan pointed out in the comments that the 18 million number is completely wrong.  I'm leaving it there so as not to "whitewash" my original answer, but it is wrong.
So, we have that duty, and we blew it, collectively, if you feel that the outcome is one where an unfit person is going to take office.  Too late for buyers remorse after the fact.  We had about 15 months to send any unfit candidates packing.  That should be plenty of time to figure it out.
Comment: "in this election I heard we had 18 million less votes cast than in the previous cycle."  That's rather obviously false.  [2012 votes for president](https://en.wikipedia.org/wiki/United_States_presidential_election,_2012#Results):  129,085,410.  [2016 votes](https://en.wikipedia.org/wiki/United_States_presidential_election,_2016):  estimated 131.7 million.  That's about 2 million higher, not 18 million lower.  Of course, almost 5% of those voted for third-party candidates, so Clinton's vote was about 5 million behind Obama's and Trump was behind Romney's.
Comment: The original question implies that the vote has already taken place.  The question is how to block a legitimate vote.
Comment: While that may be one interpretation, it does not explicitly say so. If we want to "infer," you can infer that, since my answer clearly delineates that any responsibility lies in the informed use of the vote, and the vote has passed, the answer would be "no."  Pointing out that there is such a responsibility, and that it was readily and easily available for use absolutely addresses the "inference" of the question. Odd that you can infer from the question, but not the answer.
Comment: @Brythan - thanks.  That was, literally, morning after commentary, and that sounded like a pretty huge number, which is why I've been saying that it was a number "I heard."  Thanks for supplying the facts.
Answer: The election is over and done with. As Citizens, our job is finished. We've cast our votes and played our part. Legally, we don't have a Do-over button we can smack if we didn't like the result.
As for Morally, it depends. If you believe Trump is Nu-Hitler, then you're morally required to do something. However, I personally believe that representing him that way is overblown fear-mongering, and that from a moral standpoint we need to respect the results of the election.
Comment: Not quite true. The state legislatures still have to appoint electors by December 13th who will vote on December 19th: http://politics.stackexchange.com/a/13171/2565
Answer: You do not have the right to overturn a fair and accurate election.  You do not have the right to determine fitness. The vote that just occurred did that.
You may want to peruse the laws and penalties against public insurrection: What are the US federal crimes and penalties against public insurrection?
I thought the advocating the overthrow of government particular pertinent in this regard.

Whoever knowingly or willfully advocates, abets, advises, or teaches the duty, necessity, desirability, or propriety of overthrowing or destroying the government of the United States or the government of any State, Territory, District or Possession thereof, or the government of any political subdivision therein, by force or violence, or by the assassination of any officer of any such government; or
Whoever, with intent to cause the overthrow or destruction of any such government, prints, publishes, edits, issues, circulates, sells, distributes, or publicly displays any written or printed matter advocating, advising, or teaching the duty, necessity, desirability, or propriety of overthrowing or destroying any government in the United States by force or violence, or attempts to do so; or
Whoever organizes or helps or attempts to organize any society, group, or assembly of persons who teach, advocate, or encourage the overthrow or destruction of any such government by force or violence; or becomes or is a member of, or affiliates with, any such society, group, or assembly of persons, knowing the purposes thereof—
Shall be fined under this title or imprisoned not more than twenty years, or both, and shall be ineligible for employment by the United States or any department or agency thereof, for the five years next following his conviction.
If two or more persons conspire to commit any offense named in this section, each shall be fined under this title or imprisoned not more than twenty years, or both, and shall be ineligible for employment by the United States or any department or agency thereof, for the five years next following his conviction.
As used in this section, the terms "organizes" and "organize", with respect to any society, group, or assembly of persons, include the recruiting of new members, the forming of new units, and the regrouping or expansion of existing clubs, classes, and other units of such society, group, or assembly of persons.
(June 25, 1948, ch. 645, 62 Stat. 808; July 24, 1956, ch. 678, § 2, 70 Stat. 623; Pub. L. 87–486, June 19, 1962, 76 Stat. 103; Pub. L. 103–322, title XXXIII, § 330016(1)(N), Sept. 13, 1994, 108 Stat. 2148.)
Comment: While correct, certain irony is to be found in the fact that USA as a sovereign country did, after all, originate in **insurrection**.
Comment: @user4012 I find more irony in the fact that people that a couple of weeks ago were claiming that "the elections are rigged" and "there is a conspiracy" now have their mouth full of "fair and accurate election" (wtf is an "accurate election?") and posting left and right the penalties for "advocating the overthrow of the legitimate government". But hey, congratulations on their newfound belief in democracy...
Comment: @SJuan76 - Well duh. Humans are, y'know, hypocritical. It's a fact of nature. Both sides take up whatever principles support their desired outcome and reject the ones that don't. Having said that, primaries were definitely proven to have been rigged against Sanders - and this is coming from someone who dislikes the idea of Bernie as President.
Comment: @SJuan76 Interestingly, when asked, Trump still maintains his belief that the election was rigged. He's not necessarily wrong. How hard would it be to *modify* the vote count in an area by, say, 1%? Consider that the political establishment controls the counting of votes, and that 89 electoral votes were decided by a swing of less than 1%. The potential for there to have been shenanigans is not zero.
Comment: An accurate election is one where there is one man, one vote.  Why that has to be explained is beyond me.
Answer: You do indeed, it's called the Democratic Process. By voting for your preferred candidate you can have them elected as president, and to prevent an unfit person from entering office, you simply need to ensure that they do not get a majority of states to choose them over another candidate.
Answer: Wikipedia has an interesting article on the Right of Revolution.  That right continues to be enshrined in several state constitutions.  It's not clear whether it's an individual right (as discussed here) or a collective right (a more widespread uprising)
Answer: You have the right to vote your conscience and judgment. You have the right to voice your opinions if you don't like the outcome. However, in a democracy, you don't have the right to disrupt the democratic process if you don't like the outcome. That would be imposing your views upon others, while disrupting due process.
In the US, there are other ways to protest an election. Consider what happened after 2008, when the democratic party swept the presidency and both houses of congress. In 2010, voters went to the polls and gave the House of Representatives, which is fully re-elected every two years, to the republican party. Hint: There is another midterm election coming up in November, 2018.
As for someone being 'unfit for the office'... in the 2016 US presidential election, it is arguable that neither of the prime candidates was fit to hold the office. US voters should be asking themselves how both major political parties could fail so badly, at the same time.
Imagine someone in 2008 deciding that they would disrupt the Oath of Office, because they didn't like the outcome. That might help you get a clearer perspective on what you are suggesting.


What kind of soil does aloe vera prefers?

Question: (I'm new to planting)
Can I use native soil from a nearby grass field? Should I also add some plotting mix?
Answer: Never use garden soil, soil from out of doors in pots for potted plants.  Hard and fast rule.  Use only sterilized potting soil, potting medium.  There is rarely any 'soil' in a potting mix.  The key is sterilization.  You do not want any disease or hibernating insect to find a great vector to grow and multiply.
Use just plain cheapo sterilized potting soil.  Do not buy any potting soil with gimmicks such as water holding gels and sponges!  Make sure that absolutely no fertilizer has been added to that soil either.
You need to be in total control of fertilizer.  Less is Best, More is Death and None is Dumb...a little ditty about fertilizer to go by.
No gravel or rocks or packing peanuts should be used beneath the soil.  Use just soil above the drainage hole. Prop the pot up off the surface it sits with 1/4 inch tiles or 'pot feet'...
For your aloe vera make sure the pot is not too large.  A cactus or succulent plant 6" high 6" wide should be planted in a 6 to 8" diameter clay pot.  3 to 4 inches in height.  More shallow than tall. 1" from soil to rim. Too much wet soil will kill these desert plants. Water ONLY when very very dry.  Use a bit of fertilizer (Osmocote 14-14-14 extended release 1/2 the amount the directions suggest).  Great lighting...south window be careful with direct sun through the window. Never take the plant out side and put it in direct sun either nor take a plant indoors used to no sun and put it in direct sun from the kitchen window.... without acclimation.
Use ONLY potting medium (soil) for ALL plants planted in pots, planters.  Never use garden soil for any potted plant.  If you want more information about why this is necessary we could talk more...
Note: Yes, Walmart will have a garden aisle where you can buy a pot, the fertilizer and the potting soil.
Potting soil can be found in grocery stores, I kid you not.  Walmart, Home Depot, Lowes, Nurseries...some countries are unable to get potting soil of any kind so I've learned.  No gimmicks or fertilizer!
Look for a small bottle of Osmocote All Purpose fertilizer 14-14-14 extended release.  That will be good for ALL plants.  Use half of the recommendation amounts.  When my Aloe Vera grew up and matured to have leaves 3 to 4" in width, then that aloe gell stuff became phenomenal on cuts and open sores.  Stinks very very badly but your cut or oweee turns black like a scab in half an hour!  Amazing plant.  Keep it in one spot only unless you have a covered patio you could take it out for the summer. No direct sunlight.   Have fun!
I went out to find I am right about the needs of succulents.  Potting soil with water holding gimmicks is very bad.  Here is a fairly good article with solid information.
cactus and succulent needs
Comment: Thanks! Where can I find sterilized potting soil? Walmart?
Answer: You don't say where you are located in the world so it's hard to know what your soil is like. Succulents in general prefer a fast draining, open, low-organic potting media. Bagged brown potting soil or high-organic, clay soil is not the best choice. Anything with peat will make it very difficult (impossible) to re-wet once it dries out. There are several commercial cactus and succulent potting mixes available either in stores or online. Supplement that with pumice, pearlite or a calcined clay product to create open spaces and a reserve of moisture.
Any nonsense you read about putting succulents in tiny pots is just that; nonsense. The pot size needs to be appropriate for the size and mass of the plant. The growth habit of your plant will also help determine the best pot size. Is this a plant that offsets prolifically, like many Aloe do? You might need a larger pot.
Depending on your climate you can use either terra cotta or plastic pots. I prefer lower profile pots, sometimes called "tulip" pots. Any pot should have at least one drain hole.
Don't bury the plant too deep, the root/stem junction should be just small bit below the potting media level. You can cover the top of the potting media with fine gravel (3-6mm) generally referred to as top dressing, it's optional, but widely used by cactus and succulent growers. This keeps things neat and clean and keeps moisture away from the base of the plant.
Now, you can pot your plant in a tiny pot with peat-based soil and it will probably survive, if you want it to thrive it needs a potting mix closer to habitat.
Good luck!
Comment: @Tim Nevins  Peat, such a great medium is now a no no to use because Peat has become an endangered resource.  Coir, Cocofiber is a good substitute.  But I don't think cactus and succulents are accustomed to acidic soils.  Acidic soils are in high rainfall areas.  High Organic matter in native soil is only found in warm, high rainfall areas, not deserts.  Only makes sense anyway.  I'll go look this up...Nice answer btw.  You are walking them through the steps, putting the steps in order.  Plants in pots should never be planted in any garden soil ever.  Potted plants need sterilized medium.
Comment: @Tim Nevins Check out the article I posted in my answer...let me know what you think...


Earthquake time history analysis

Question: Time history analysis of earthquakes for structures, is a NON-LINEAR dynamic method correct?
Then why is there also something called "LINEAR response history analysis"? What is the difference of this from non linear time history analysis?
Answer: A linear analysis is ... linear. If you increase the loads by a factor of two, the results increase by a factor of two. If you increase the loads by a factor of 1 million, the results increase by a factor of 1 million, even though the results are likely to be wrong.  The analysis does not understand that other effects occur when the results are so large. (Those other effects are the stiffness of the structure changes, and the direction of the load changes, and so on.)
A nonlinear analysis does not have a linear relationship between the load and result. Doubling the load may only give results 1.5 times as much (the structure stiffens) or a result 3 times more  (the material yields or gets weaker for example).
Time history indicates it is a dynamic analysis. The loafs and results can change over time.
Answer: The linear time history analysis of the response of the structure is calculated at small time intervals sequenced with appropriate seismic load, maybe even after the ground motion stops until the structure stops from vibrating.
The FEA's programs either use Duhamel integral or numerical methods to calculate stress and deformations. During the loading and unloading, the structure's stresses don't go beyond elastic linear levers.
The nonlinear time history analysis or Push-over method allows during the short sequence of time intervals again, for stresses and deformations of the structure to go beyond the elastic limit into the plastic limit with high angry absorbing deformations.
This analysis is mostly used to verify the viability of the structure in a very large earthquake to while deforming beyond a repairable state, still, give the occupants time to safely exit the structure.

Earthquake time history analysis


Developing ExactTarget app in JAVA SDK

Question: I am newbie to ExactTarget app development. I'm trying to build an app using Java SDK  but I couldn't find any sample code to begin with. Can anyone provide me sample Java code for ExactTarget app development?
Comment: Hi Manoj.Can you provide more details on what you are trying to do? -ian
Comment: @IanMurdock I have requirement to build an app for a company some thing like inventory ...Since im very new to this ET development and i Know oly java...I dont know from where to begin ...thts y i need  help from some ultra ET specialist like you :-)
Answer: It depends on what you are trying to do. In general, to use the SDK, you need to get a client ID and secret from App Center on Code@ExactTarget, instantiate an ETClient object with that client ID and secret, then use that instance as the authentication context for future interactions. For example, here is how you retrieve a data extension and add a row to it:
// specifiy client ID and secret
ETConfiguration configuration = new ETConfiguration();
configuration.setClientId(YOUR_CLIENT_ID_GOES_HERE);
configuration.setClientSecret(YOUR_CLIENT_SECRET_GOES_HERE);

// instantiate ETClient object
ETClient client = new ETClient(configuration);

// retrieve the data extension "products"
ETFilter filter = new ETSimpleFilter("Name",
                                     ETFilterOperators.EQUALS,
                                     "products");
ETDataExtension dataExtension = client.retrieveDataExtension(filter);

// add a row to the data extension "products"
ETDataExtensionRow row = new ETDataExtensionRow();
row.setColumn("id", "123");
row.setColumn("name", "My Great Product");
row.setColumn("price", "42.00");
dataExtension.insert(row);

As Ivan mentions, you can also use the raw API in Java as well.

Developing ExactTarget app in JAVA SDK


Genymotion 2.8.1 - Can't flash Play Services on any Virtual Device

Question: So, on Genymotion 2.8.1, I've tried flashing Play Services on a number of Virtual Devices. None works. I get the error along the lines of "Flashing xyz zip failed for an unknown reason, check the logcat for more info"
In the logcat, I move to where the error starts, and there's NO error message giving info as to what is happening, except something like 'Flashing stopped'
I've downloaded about 4 different virtual devices of different OS versions, and I'm beginning to suspect Genymotion 2.8.1 has a problem.
Any idea how to use or flash Play Services onto Genymotion 2.8.1 or any alternative means to install apps from Play Store?
Answer: You can use old vision.  v2.5.4 is usable.
http://azodl.blogspot.tw/2015/06/genymotion.html


How google home and our smartphone get connected together to send WiFi password to google home?

Question: As you all know in order to connect our google home devices we use a special google home app on our smartphone. But the questions is , suppose that app know the current WiFi password, how that password gets sent to google home itself when google home has not been connected to any WiFi yet? is it via Bluetooth or something else?
Answer: Google home's initial setup is likely similar to the initial setup on a Chromecast device. The Chromecast acts as an access point (i.e. something a WiFi-enabled device can connect too, just like your router). The Google Home app is programmed to search for and connect to this access point. Once connected, the two devices can communicate information between eachother. In fact, when setting up a Chromecast device, a message is displayed in the Google Home app stating that "you may be disconnected from WiFi for a moment".
Google Home probably works in the same way - it acts as an access point, gets paired with the phone and they exchanged information/passwords and then Google Home connects to the WiFi.


Can the same net-list file be used for ASIC design flow as well as FPGA design flow?

Question: I have mostly worked on front-end part and don't know much about back-end stuff. I have gone through the reading about the various abstraction levels of design flows of FPGAs and ASICs. I was wondering that is it possible that netlist generated out of same VHDL/Verilog source files for FPGA be used for ASIC design flow as well to carry forward further design developments. I know netlist gets generated after the synthesis stage which depends on synthesis tools of the particular company say Xilinx, ALTERA, Synopsys etc. (some back-end stuff which I'm not much aware of), but a netlist is nothing but a description of the connectivity of modules Right! providing nothing more than instances, nodes, and perhaps some attributes of the components involved. So, going back to the question "Can the same netlist be used for ASIC flow as well as FPGA design flow?"
Comment: Not a complete answer, but google "Altera HardCopy". The Quartus tools can compile a design for FPGA, and then transfer that netlist to a matching ASIC design.
Answer: Assuming the same logic cells or library cells are available on both FPGA and custom ASIC process and the cells with the same functionality have the same name, then yes, you could use the netlist for either.
If only the cellnames are different you could do a search and replace to translate it.
But I do not expect this to be the case as FPGA library cells are usually more complex to offer more flexibility.
Custom ASIC libraries usually only include very basic logic cells in order to keep things small (in size) because as you know, size = money.
You could in theory make a translation library to use FPGA netlist on an ASIC. But creating a new netlist specifically for the ASIC library and the cells which it has available will usually result in a more efficient and smaller design as you get rid of the overhead which will always be there in a netlist for an FPGA.
Answer: A generic RTL netlist might be fine, but not a technology specific netlist.  The former is just the same as your HDL code, but re-expressed at a gate level, but typically arranged to fit better for your targeted technology.
Since you still need the ASIC synthesis tools, you might as well start with your HDL in both cases... not to mention, the advantages of allowing the tools to target the technology you want without having to "undo" a previous targeted technology.
Yeh, I don't know, maybe, but, don't do that.


Why not use a snooker cue on a standard pool table?

Question: What are the benefits or drawbacks of using a snooker cue rather than a standard cue on a regular pool table?
Comment: You could improve this question by specifying what type of pool you are referring to.
Comment: Generally, American 8-ball on a 9-foot table. 30 years ago in my 40s I used a nice little 2-piece snooker cue on bar tables [8-ball] and out-shot most everyone. That cue was lost years ago. Now [nearing 80] I'm trying to regain my game at the senior center and having terrible luck with a 13mm tipped cue. I'm trying to figure out if I should gamble on the expence of a new or used snooker cue. Oh, and my left eye has distortion in it now. So, there's that too. Thanks for the info so far. It's been helpful. :) pip
Answer: There's a few differences between a snooker cue and a pool one:
Weight: Because pool balls are heavier than their snooker cousins pool cues tend to be heavier to match. The weight distribution is also different - pool cues are heavier on the grip where snooker cues have more weight at the tip.
Tip size: Snooker cues have a narrower tip (~9-10mm vs 12-13mm)
So what do these differences mean? Snooker cues are optimized for accuracy rather than power or cue-ball control as pool cues are. This is the case because of various factors - snooker balls are smaller, the pockets are rounded (i.e. you have to be more accurate to pot then in pool), the table is significantly bigger which further increases the need for accuracy.
So to answer your question if you were to use a snooker cue on a regular pool table you'd benefit from potting accuracy but lose out on the ability to hit harder and to position the cue ball were you wanted. Additionally while the tip is only slightly smaller the difference in ball sizing means that using a snooker cue to hit pool balls increases your chances of miscuing and imparting unwanted spin on the cue ball (and ultimately object ball as well).
Comment: Here in the UK pool balls are actually smaller and lighter, and using a snooker cue makes far more sense than a pool cue.
Comment: @AndyP True.. I must confess I had presumed from the way the OP had worded the question that they were talking about an American style pool table.
Comment: I agree with @AndyP - I play with a snooker cue on UK tournament tables and you can easily position the cue ball wherever you wish with side, top and bottom applied.


the relationship between maximizing the likelihood and minimizing the cross-entropy

Question: There is a statement that maximizing the likelihood is equivalent to minimizing the cross-entropy.  Are there any proof for this statement?
Answer: Here's a worked example in the case of iid binary data, each with a  success/failure recorded as $y_i \in \{0,1\}$.
For labels $y_i\in \{0,1\}$, the likelihood of some binary data under the Bernoulli model with parameters $\theta$ is
$$
\mathcal{L}(\theta) = \prod_{i=1}^n p(y_i=1|\theta)^{y_i}p(y_i=0|\theta)^{1-y_i}\\
$$
whereas the log-likelihood is
$$
\log\mathcal{L}(\theta) = \sum_{i=1}^n y_i\log p(y=1|\theta) + (1-y_i)\log p(y=0|\theta)
$$
And the binary cross-entropy is
$$
L(\theta) = -\frac{1}{n}\sum_{i=1}^n y_i\log p(y=1|\theta) + (1-y_i)\log p(y=0|\theta)
$$
Clearly, $ \log \mathcal{L}(\theta) = -nL(\theta) $.
We know that an optimal parameter vector $\theta^*$ is the same for both because we can observe that for any $\theta$ which is not optimal, we have $\frac{1}{n} L(\theta) > \frac{1}{n} L(\theta^*)$, which holds for any $\frac{1}{n} > 0$. (Remember, we want to minimize cross-entropy, so the optimal $\theta^*$ has the least $L(\theta^*)$.)
Likewise, we know that the optimal value $\theta^*$ is the same for $\log \mathcal{L}(\theta)$ and $ \mathcal{L}(\theta)$ because $\log(x)$ is a monotonic increasing function for $x \in \mathbb{R}^+$, so we can write $\log \mathcal{L}(\theta) < \log\mathcal{L}(\theta^*)$. (Remember, we want to maximize the likelihood, so the optimal $\theta^*$ has the most $\mathcal{L}(\theta^*)$.)
Some sources omit the $\frac{1}{n}$ from the cross-entropy. Clearly, this only changes the value of $L(\theta)$, but not the location of the optima, so from an optimization perspective the distinction is not important. The negative sign, however, is obviously important since it is the difference between maximizing and minimizing!

Some more additional examples and more general result can be found in this related thread: How to construct a cross-entropy loss for general regression targets?
Comment: @gebbissimo It depends on what you mean. I'm not aware of a probability model which results in this loss function. On the other hand, this post explains why using this loss with non-binary targets in [0,1] are still useful models for training a neural network, without appealing to a probability model. https://stats.stackexchange.com/questions/394582/why-is-binary-cross-entropy-or-log-loss-used-in-autoencoders-for-non-binary-da
Comment: Is this specific for logistic regression or applicable in general such as to a deep/convolutional/recurrent neural network?
Comment: The definition of the loss/MLE function doesn't change -- as you can see, the likelihood is not tied to any particular functional form of the model -- so we can infer that cross-entropy loss and the binomial MLE are the same in both logistic regression and NNs. From an optimization perspective, the point of departure is that logistic regression is strongly **convex** under certain assumptions, while neural networks are generally **non-convex.** For example, you can permute the weights of a neural network and obtain the same loss, so there are many $\theta^*$ values with the same loss.
Comment: Same loss or same minimum loss?
Comment: Permutation equivalence of weights in an NN implies that if you have obtained some loss $L(\theta)$, then permuting the weights in a particular way will give the same loss value for the permuted vector $\theta$. So under these kinds of permutations, the losses are equal. This is true for minima corresponding to $\theta^*$ as well as the general case $\theta$ which do not minimize $L(\theta)$.
Comment: @Sycorax: Is it possible to exand this derivation to "soft" float labels [0,1]?
Comment: @Sycorax: Thanks for the super quick reply! Haven't found this thread before and will check it now


amino acid pka of carboxylic acid

Question: Why is the pka of the carboxylic acid part of alpha amino acids (pka around 2.3 for most amino acids) quite a bit less than the pka of a normal carboxylic acid, say acetic acid (pka =4.76)?
Comment: Look at mesomer forms of the conjugate base. The more you find the more the acid is strong.
Answer: The amino group in $\alpha$-amino acids is electron-withdrawing via the inductive effect. Mesomeric (resonance) effects cannot occur here because there is no conjugation of the nitrogen lone pair with the carboxyl group. There are two equivalent ways of looking at how the EWG affects the acidity:

It stabilises the conjugate base via withdrawal of electron density from the negatively charged oxygens;
It polarises the $\ce{O-H}$ bond further than in the unsubstituted carboxylic acid, making the proton more prone to dissociation.

Therefore, the $\mathrm{p}K_\mathrm{a}$ of glycine is $2.34$, significantly lower than the unsubstituted acid (acetic acid, $\mathrm{p}K_\mathrm{a} = 4.76$). Similar effects are seen in 2-chloroacetic acid ($\mathrm{p}K_\mathrm{a} = 2.86$).

As for the comparison between glycine and 2-chloroacetic acid, one thing to bear in mind is that glycine exists as a zwitterion at neutral pH. Therefore, the relevant acid-base equilibria are:

For $\mathrm{p}K_\mathrm{a1}$, which you are interested in, note that the substituent is no longer merely a $\ce{-NH2}$ group but is now a $\ce{-NH3+}$ group. Despite nitrogen and chlorine having extremely similar Pauling electronegativities, the positively charged nitrogen is now more electron-withdrawing than a simple uncharged chloro substituent.
One could draw some parallels with aromatic chemistry: aniline is rather unreactive (compared to chlorobenzene) in electrophilic substitution under acidic conditions, where it is protonated. Of course, the reactivity of aromatic rings is a kinetic effect whereas $\mathrm{p}K_\mathrm{a}$ is a thermodynamic effect, but the underlying rationale is the same: $\ce{-NH3+}$ is more electron-withdrawing than $\ce{-Cl}$.
Comment: Cheers for this reply, upvoted, but I'm not going to accept yet as I'm not fully convinced for the following reason: chlorine has the same electronegativity as nitrogen so why is there still a non-negligible difference in the pka of 2-chloroacetic acid and glycine. Furthermore I'd expect the former compound to be even more acidic because nitrogen pulls electron density from 3 bonds (2 hydrogens and the rest of the molecule) whereas chlorine is only pulling electron density from the molecule itself, the only moiety it is attached to.
Comment: Furthermore, fluoroacetic acid (fluoro electronegativity > nitrogen) is still observed to be less acidic (pka 2.6) than glycine.
Comment: Unless the substituents are extremely similar (e.g. F, Cl, Br, I), it is difficult to simply compare substituents just on the basis of Pauling electronegativity, and a direct relationship may or may not exist. Nevertheless, it is a good question and I will expand the answer a little bit because there is a second aspect of glycine that I neglected earlier.

amino acid pka of carboxylic acid


Chinese 'Tao' ('Dao') vs South African Ubuntu

Question: What are some similarities and differences between the Chinese concept of Dao in Daoism (https://en.wikipedia.org/wiki/Tao) versus the South African concept of Ubuntu (https://en.wikipedia.org/wiki/Ubuntu_(philosophy))?
Comment: In your question title you say "Chinese Dao" but in the body you restrict it to how it is used in Daoism (the term is actually used by all major schools of Chinese philosophy). Do you want to ask specifically about Daoism?
Comment: Ubuntu is, as the Wikipedia page says, "a is a Nguni Bantu term meaning "humanity". It is often also translated as "humanity towards others", but is often used in a more philosophical sense to mean "the belief in a universal bond of sharing that connects all humanity". The Dao is  not a material substratum but the source of all consciousness - and not limited to humanity. The first is a sociological concept, the second is a philosophical concept. There might have been some practical interpretations of the Dao in Confucianism but beyond that they are not related.
Comment: @Swami Vishwananda - I would rather say that all expressions of the unity of consciousness are directly connected, and would agree with Schopenhauer that they are the 'breakthrough of a metaphysical truth'. It seems to me very likely that Ubuntu is connected to Tao, and to Nirvana, Unity, God and even Kant''s 'thing in itself'. The truth will out, as they say.
Answer: If I understand the question correctly I believe you are referring to the totality of Dao within Daoism. @virmaior is correct that Tao/Dao is used in other Chinese philosophies as well but we shall limit this discussion to only Taoism (see Confucianism ethical Dao)
Dao is something unexplainable/beyond comprehension (words can not adequately describe the totality of Dao) but it is within everything and is the fundamental energy all things share. The Inner Chapters are an excellent starting point to understanding Daoist Dao.
I believe that Ubuntu is generally more like the Confucius concept of Dao. The idea of ethical/moral treatment of others to be a key to humanity is more concerned with the acts of individuals and not the all encompassing energy of Daoist Dao. (from my small understanding of Ubuntu, so if someone knows more please comment and correct me)
Comment: Not a correction but... the ethical treatment of others would be directly motivated by the all-encompassing nature of Consciousness, thus the shared identity of sentient beings. You may be right about Ubuntu being more Confucian than to do with the Inner Chapters, but under the surface I suspect it all bubbles up from the same source.  .
Comment: My understanding is that that would be a Daoist perspective on treatment of others, by following Dao's natural order one would treat others in a way that falls in line with basic ethical and moral treatment. For Confucians Dao its more of the Daotong or the Confucian way to restore the dao.. which definitely bubbles up to the overall ideal. 2 different perspectives that lead to the same ideal Dao


Does the gravitational pull of the moon affect the composition of Earth's atmosphere?

Question: In particular, does the pull of the moon affect the amount of water vapour in the Earth's atmosphere? In other words, if the moon were larger, or orbiting more closely to the earth, would the increased gravity cause the composition of the atmosphere to change?
Comment: The gravitational force of the moon causes tides in ocean and atmosphere, not direct changes in composition. Perhaps you might have interest in atmospheric tides... http://earthscience.stackexchange.com/questions/182/what-can-we-learn-by-studying-lunar-atmospheric-tides
Comment: @LulalaBoss: I inverted the question and the title, so that the title is more general, and less hyothetical,  and left the details in the question body. I hope that is OK. If not, you can always revert the changes.
Answer: The atmosphere is continuously mixed by turbulence, so no sorting of its  ordinary components can occur easily and rapidly. Twice a day change, anyway, is far too fast for anything but some tidal effect on pressure and thus on temperature. Ok, these might indirectly slightly modify some thresholds and balance e.g. between states change (water) and some atmospheric chemistry, by a fraction of what day/night change does. I wouldn't call that "change of composition", though.
Answer: The long term influences upon the Earth's atmosphere are additions, subtractions and internal variations. The additions consist of gravitational attraction of passing gas molecules from space, which is insignificant, and outgassing from the solid Earth. The latter is 'new' helium from radioactive processes, and volcanic gasses which are mostly long-term recycled from the surface via subduction zones.
Subtractions involve loss of gass molecules by thermal heating in the very tenuous outer regions of the atmosphere. Some of the lighter gasses, mainly hydrogen and helium, attain energies which allow them to exceed the escape velocities. This is why our atmosphere hasn't built up much higher concentrations of the light elements over time.
Internal variations are such geochemical and biological feedback processes as greenhouse gases influencing the temperature, and hence evaporation / ice accumulation, etc.
None of the above have anything to do with pressure fluctuations caused by the moons orbit.
Answer: A much larger or much closer moon would strip away the atmosphere over time. Heavier elements would go first, so the composition would change, yes.


java capping fps

Question: hello again I have a basic platformer game and I want to make an fps counter and cap the fps to 30 but I don't know how. I want this because when I start up the game sometimes the character moves realy fast and other times very slow.
Answer: You should probably use framerate-independent movement, because then you wouldn't have to care about the FPS.
What you are probably doing right now is in every frame you say position += velocity;, where position is in units of distance (whatever they may be--pixels, meters, etc.), and velocity is in units of distance per frame.
However, what you should probably do is have velocity instead be in units of distance per time instead of distance per time. Then what you would do is position += velocity * frameTime;, where frameTime is 1/FPS, and is in units of time (seconds, to be specific).
Now, no matter what the framerate is, your character will move the same distance in the same amount of time.
Answer: I believe what you want to add is a fixed timestep. If you wish to make your game's logic independent of your framerate, you'll want to look into adding a delta - a timestep that calculates the time between update calls.
For a more in-depth explanation, check out DeWitter's article: http://www.koonsolo.com/news/dewitters-gameloop/

java capping fps


Hydraulic disc brakes on cross bike (post mount)

Question: I have just bought some post mount calipers (Shimano) to fit on a cyclocross bike and separately some 160mm discs. The calipers do not quite sit flush on the post mounts (front or back) before the disc reached the back of the caliper. Should I expect to need washers to space the caliper out a bit further, and if so, what thickness?
Comment: Flat mount in particular and disc brakes on road bikes are fairly new. The are not that many people with experience (or even interest) with these. Whatever you find out by yourself, eg by skiing Shimano, would be appreciated here. Would you be so good to post it here as an answer to your own question?
Comment: Would you please include the model of your brake calipers and discs in your question? A photo of the brake not sitting flush would also be welcome.
Comment: The mount might be for a 140 mm rotor. Flat mount requires some spacers/brackets for larger rotors.
Answer: It sounds like your post-mount frame (and fork) is setup by default for 140mm rotors.   This would be expected for the frame and is not surprising for the fork either.
What you need is a post-to-post 140 to 160mm adapter.  This might be more commonly a 160-to-180 adapter, but it's the same thing.  It's moving the caliper ~10mm further away (or more like 12.5mm on top and 7.5mm at the bottom).

Shimano makes the SM-MA-F180 P/P2.
SRAM makes the "20S/20P" adapter also for this purpose.  (This is the one I have used.)  From SRAM's instructions publication, there is a handy table that illustrates that going from 140 to 160 uses same adapter as 160 to 180.

You might want to first check with a local shop to see if they just have the spacers you need in a bin.  Otherwise you can definitely find it online (e.g. at jensonusa, but obviously it can be found elsewhere too).
Answer: Please note: while the question asks for post mount this answer pertains to the flat mount standard. Therefore, the following is not relevant to post mount brakes whatsoever.

Many Shimano brake calipers for road bikes are designed for 140 mm rotors. Two different types of mounting adaptors, fore and aft, may be used to mount larger rotors.
The rear adapter (eg SMMAR160DDA) is an aluminium bracket that adds 10 mm to the mount height through its own thickness and by moving the caliper a little forward.
The forward adaptor (eg SMMAR160DDA) places the brake mount further up on the fork.
Comment: Sounds like this question is about post-mount, not flat-mount.
Comment: @HansL thankee! You're right I wholly confused the two. Regardless of *post mount* being mentioned half a score in the question. I shall add a warning to my answer presently.


Find the next vertices at the intersect line

Question: I'm Trying to calculate the angle between two intersected lines at geometric network (simple edge)in order to check if the lines are close to be perpendicular. I already have an Array of the intersection vertices and a function that calculate the angle using Pythagorean theorem. How I can get the next vertices at the intersect line, in order to calculate the angle between this vertices and the intersect point using the function ?
Comment: Can you perhaps include a diagram of what you are after?  This seems like the third similar question that you have asked without giving much context to what you are trying to do.
Comment: See these for ideas: [1](http://gis.stackexchange.com/questions/44065/how-to-calculate-the-incidence-angle-of-a-polyline) [2](http://gis.stackexchange.com/questions/21038/how-to-find-the-angle-between-intersecting-features-in-two-featureclasses)
Comment: I'm developing QA tools for geometric network for water utilities - to check the quality of the digitizer who collect the data. At my previous questions i developed a tool to check angle between vertices- steel pipes can have only a specific angles. Now I'm after the angles between lines.
Answer: You tag this question as a python question so assuming you are using 10.1 then looking at the page on Polyline geometry in the Help file it shows that Polyline has a method called getPart which returns a list of points. If you know which end your intersection point is then its just a matter of stepping through the list.


what is the actual point of vega on real option data

Question: For a call option, we know that the vega is the derivative of the price wrt to the volatility.
However the volatility, in that context, actually refers to the implied volatility of the specific call contract at this moment, which is inferred from the option price.
So, knowing this, what is the purpose of the vega ? We are essentially saying "if the implied vol rises by 1%, the price rises by X", but the cause that will trigger a change in the implied vol is the price of the option itself.
Comment: The question is backwards, you should ask why we need the price!
Answer: Think of it this way, the change in option premium is roughly the sum of changes due to delta, gamma, theta, rho, and vega. Now for a long dated option, gamma and theta don't change dramatically day to day, and let's say you have delta hedged your option. Then your P&L is mostly just driven by changes in implied vol – i.e., vega.  So vega matters a great deal when you are trying to manage risks of an option book – you can isolate different sources of risk (due to underlying, due to time, due to implied vol) and hedges them accordingly.  Similarly, there are also strategies to trade (almost) purely on implied vol – if you carefully hedge out all the other risks, then your P&L will be completely driven by vega. This, of course, is because of the one-to-one mapping between implied vol and option pmreium, just like you said.

I thought about it more. If you are familiar with bonds, I think they provide a good analogy. As you may know, bond price and bond yields also form 1-to-1 mapping, with "DV01" or "Duration" measuring the sensitivity of bond price to yield changes. The value of "DV01" (or duration) is that they provide a consistent framework for measuring interest rate risks. Two bonds might be trading at very different prices (e.g., if one has much higher coupon than the other), but they may have similar duration, so the two have similar risks. Simply put, bond prices are not particularly meaningful, but bond yields are more comparable (that's why we plot the "yield" curve, not bond "price" curve...), and yield-based risk metrics are also more useful.
Options are the same. Prices are not particularly meaningful, while implied vols are more comparable across different options, allowing for easier comparison, hedging, and P&L attribution. As I mentioned above, if you can carefully manage other risks, it's possible to trade vega directly. In fact, we frequently look at stuff like spreads of two implied vols and trade on relative value in this way.
Comment: but in that case, can we really say that the remaining risk is volatility risk and not just "other types of risks not really explained" ? For instance, I understand that the remaining pnl is driven by vega, but that's just a way of saying that the remaining pnl is due to a change in the option price... which doesn't say much
Comment: @lezebulon You're absolutely right that the attribution I described is an approximation and there are residuals, but the approximation is a VERY good one in practice. The point is – if you just say price changed, that doesn't tell you anything about how to hedge. But if you have two options, option A has a vega of 2, and option B has a vega of 4, then you know that to hedge B with A, you need two units of A (all else equal). The point is, you now have a much more "controlled" framework to hedge using different instruments.
Comment: but since option A and B are different contracts, there is no reason that a change in A's i.v will result in the same change of B's i.v  right ? So I don't see how this hedge can work
Answer: As an option trader you may well prefer model and forecast volatility rather than the specific price dynamics of the stock and option contract. This is a straight-forward consequence of the Black-and-Scholes framework (*). If you own an option, knowing vega allows you compute the expected PnL on your position and manage risks with respect to your realized volatility forecasts.
(*) As a matter of fact, the real-world stock-price drift is not an input of the B&S formula.
Comment: I don't really see how computing the vega with model volatility changes anything. If the calibration is done correctly the implied vol given by the model is the same as the i.v. from the market. The fact that you may have volatility forecast for the future doesn't really change the current value of the vega for a given contract, at the current time.
Comment: (1) your calibrated model gives you the current view of the market on the option price. If the markets were perfectly efficient then you would be right but markets are inefficient so you might have different expectations of the future so you might forecast changes in the implied vol or ultimately a different realized vol down to maturity (2) @haginile explains it very well: you use the _current_ vega to assess the pnl impact of shifts in volatility. Therefore, you can hedge positions by looking at vegas.


What's the difference between meminisse and memini?

Question: I'd love to get a tattoo saying 'remember' in Latin, but would rather not use memento. Would it be possible to either use meminisse or memini? I'd like remember to be like a reminder for myself to remember how I felt at a particular moment in the past. Hope this makes sense!
Comment: Welcome to the site, and nice question! This has to do with verb conjugations. It could help write a more customized answer if you tell us whether you speak any languages other than English
Comment: i have a question too. is there any way to differentiate "i don't remember, i won't/ can't/ wouldn't". i learned there aren't modal verbs in latin but i wanna tattoo from these, so...
Answer: They are different forms of the same verb.
Here are some of the over 30 forms:

meminisse = "to remember"
memini = "I remember"
meminimus = "we remember"
meminerunt = "they remember"
memineram = "I remembered"
memento! = "remember!"
meminero = "I will remember"

The form you need depends on what you want to say.
Is it the statement "I/you/we/… remember", an order "remember!", a description of the action "to remember", a wish "I wish I remembered" (different forms for real and irreal), or something else?
Also, you might want to consider adding more words, like "we remember her" or "I will remember myself".
Both meminisse and memini are possible, but they mean different things and there are plenty of other forms of the same verb.
If you have found something you want to say in the text, please ask a new question to find how to phrase it in Latin.
Remember that when translating short phrases like the ones one would see in a tattoo or a coat of arms, it is not enough to give the English phrase, but you should also describe what is the message you want to convey.
Comment: @DiGascon I converted your reply to a comment since it doesn't endeavor to answer the question. But I want to point out that neither translation is correct. *Meminisses* is 2nd person singular ("you") pluperfect subjunctive, which, because it is a defective verb, means something like "you might have remembered" or "you should have remembered" (depending on the surrounding grammar, of course).
Comment: This one is missing: Meminisses = It means "Remembering"....or "I hold in memory"
Comment: @cmw And perhaps more importantly, my answer is explicitly giving only a sample of the many forms. It's missing way more than one form, and with every intention.

What’s the difference between meminisse and memini?


Make MultiViews work even if the requested file does exist

Question: From the Apache 2 docs:

The effect of MultiViews is as follows: if the server receives a request for /some/dir/foo, if /some/dir has MultiViews enabled, and /some/dir/foo does not exist, then the server reads the directory looking for files named foo.*, and effectively fakes up a type map which names all those files...

Is there any way to make MultiViews do its magic even if the requested file does exist? For example I might have these files:

foo.html
foo.html.gz

When /foo.html is requested, I want to return foo.html.gz if the Accept-Encoding: gzip
header is sent.
MultiViews can do this fine, but you have to either request just /foo or rename foo.html to foo.html.en (which is hackish, and doesn't work if you request from a non-English browser).
Answer: This will make it load the .gz file if gzip compression is accepted. Otherwise it'll skip this rule and just load the normal html file.
Note: You must have the mod_rewrite module installed to use this.
RewriteCond %{HTTP:Accept-Encoding} gzip
RewriteRule ^(.*).html$ $1.html.gz [NC,L,QSA]


Record webcam video along to music

Question: I was wondering if there are any video editors available for Windows 7 that allow one to play an audio track while recording so the two stay in sync. Syncing by hand is a nightmare, and while I am familiar with both Windows Movie Maker and Premiere Pro CC 2014, neither are able to do this. WMM requires video before adding music, and Premiere Pro can't record from a webcam!
Answer: It's the sort of feature VirtualDub would have. I have no way to test this, however :(
http://www.virtualdub.org/
If not directly, you can probably trick it into having it through plugins and filters. If you can get it to pass the audio through ffdshow you can use avisynth support to replace the audio.
Answer: As I suggested in other answers before, PotPlayer is very versatile in this regard, and should cater to your need.
In particular, here's a quick how-to to get you started easily:

Press "CTRL-D" to open the device settings (or alternatively do "Right click, open, device settings") and select the "Webcam" tab
Choose your audio input device. By default, it's probably set to your microphone, but as you can see you can chose any device, including your main audio card (you might have to try a few before you find the correct one, but if you see "Stereo Input" or something like that it should be that one)
Disable the "preview audio" checkbox, or you risk getting a feedback loop through your speakers
Click "open device"

At this point, you should see a preview of your webcam. To start recording video simply press "ALT-C" (or alternatively do "Right click, Video, Video Recording, Record video...")
Hope it works for you.
Answer: You can try Adobe Presenter Video Express. It records your screen along with your webcam. You can put the music on your computer and select your  integrated microphone. Both your music and whatever you are saying will get recorded at the same.

Record webcam video along to music


Separation Rules - On Hags

Question: I was browsing and found a question asking about Night Hags.  If one member of a Night Hag coven is in the Ethereal Plane, can the others use the Shared Spellcasting ability? The OP asks about the rules for seperating a hag onto the ethereal plane.  My question is what about all the other planes?  Standard 5e rules as written.
Answer: No
The Planes, per DMG 43:

The various planes of existence are realms of myth and mystery. They're not simply other worlds, but dimensions formed and governed by spiritual and elemental principles.

The Hag ability reads

Shared Spellcasting While all three members of a hag coven are within 30 feet of one another...

The planes themselves are literally other dimensions, requiring strong magic to reach or communicate with. It's likely nonsensical to attempt to tell how far apart they are; distance is literally meaningless between them. The Ethereal plane is an explicit exception to this.
Comment: Might be worth adding that the other planes require traversing the Astral plane first to get to them, further emphasizing the sheer distance involved. It's kind of a halfway plane. Powerful magics let you bypass that requirement (like Gate), but those are extraordinarily high level spells. It might also be worth noting that the reason the Ethereal is the exception is because it literally resides in the same place, just out of phase.

Separation Rules - On Hags


Looking for Calendar app with alarm

Question: I have a Nokia Lumia 920. I need a calendar with an alarm function to remind me of my appointments. Reminders such as SMS/Email don't work for me. Have tried several calendar apps, but none of them have an alarm (sound). They  only have reminders. HELP!
Answer: The built in calendar has the ability to set reminders for appointments with sound notifications (that's what I use on my Lumia 920).
Just do the following:

Open the calendar
Hit the "+" button
Enter your details, then scroll down and hit "More details"
Then set the "Reminder" to whenever you'd like to be reminded.

In order to make sure your phone is set to play sounds for Reminders, do the following:

Open up settings, then go to ringtones + sounds
Tick the box "Play a sound for Reminders"
Comment: The problem is that this does a global alarm - I wan't to specify which appointments make a sound, e.g. like the Alarm, that overrides the silent setting on the phone.  (I've just upgraded to Windows Phone 8.1, but still can't see anything).

Looking for Calendar app with alarm


How would computers work if the number zero wasn't invented?

Question: I imagine a parallel world where people instantly went crazy and kill themselves whenever they try to conceptualize nothingness which we now known as the number zero, so no one I mean absolutely nobody will bring up the number zero be it a symbol or anything that could potentially represent nothingness unless they have a death wish. So I wonder how would such computer be like? Would it be able to be reprogrammed for a variety of tasks on par with computer we loved and liked today?
Comment: What is the difference between nobody and zero people? And the real question is how would they be able to progress to the level of building computers if they fail at basic arithmetic...
Comment: This is an interesting line of enquiry. Unfortunately, the question, as it's asked, can't really be answered without telling us more about the people. There is obviously a very strong tabu culture surrounding the whole concept of nothing. One can only imagine that people must never run low on mixed nuts at a party, lest the bowl become --- *empty!*  The last cooky is always left on the plate since no one wants to be the person who causes the existential crisis that nothingness brings with it. Explain to us how they actually deal with the tabu so they can, er, talk about nothing in particular.
Comment: @TheSquare-CubeLaw: I don't know where this myth comes from. Yes, the ancient Greeks did not normally use a positional system for number representation, but that's only because they normally did not compute in writing. When they *needed to*, for example in [trigonometric tables](https://en.wikipedia.org/wiki/Ptolemy's_table_of_chords) and such, they *did* use a positional number representation (in base 60, hah!) and that of course implies a symbol for zero, or, actually, an empty rank. It was a small raised circle, which even looked a bit like our zero, or like our degree sign.
Comment: Merchant: "I have sold all my apples! I am rich" customer: "Do you have enough apples for me to buy two?" Merchant: "huh, let me check how many apples I have." - Merchant's suicide note.
Comment: @CharlieHershberger or alternatively, they shout "_Augh! I have NO APPLES LEFT_" and every person in the market kills themselves.
Comment: (cont)... I personally think a query about the concept of a cultural inability to talk about the concept of nothing / zero / none and the tabus surrounding it are far more interesting than the mechanics of a mere computer. After all, the machine can be identical to one of ours --- it's just a matter of programming the interface to deal with a load of suicidal maniacs who'll jump out of buildings if they see a 0.
Comment: Just so you all know, the Greek had no symbol for zero and still managed to build the antikythera thingamajib which was a kind of mechanical computer.
Comment: The same way we make computers output infinite: as an exception. But wouldn't people in your world commit suicide as soon as they are hungry but realize there is no food around? This would occur long before anything like computers, or perhaps even fire, could exist. Sounds like extinction to me.
Comment: *Zero* and *nothingness* are two distinct concepts. As I write this, I'm sitting in a room full of things, far from "nothingness," yet when I look around me I see zero cruise liners, zero tractor trailers, zero eagles, and zero unicorns. In a sense, "zero" can come from a statement like $\lnot \exists x.P(x),$ whereas "nothingness" is more like $\lnot \exists x.$
Comment: How do you imagine people would survive if shouting "how many elephants can you lift?" would cause everyone in earshot to immediately kill themselves?
Comment: Well, one thing we *can* day for certain. "[Seinfeld](https://en.m.wikipedia.org/wiki/Seinfeld)" would never have been produced.
Comment: I don't think binary is the restriction here. Instead, the physics necessary to create micro processors requires math equations to describe. Can those math equations exist without the concept of zero? Someone better at math needs to weigh in on that.
Comment: I think the question to consider is not how to program a computer given a taboo against "nothingness" or "zero" or whatever it is that your fictional population is afraid of; the question is how to get through an ordinary day under those circumstances. Could such a society even invent something as simple as a light bulb, let alone an electronic computer? After all, eventually either you have to turn the light bulb **off** or it will **burn out**, either case apparently leading everyone in sight to kill themselves because the device was producing light before and now produces **no light**.
Comment: https://en.wikipedia.org/wiki/A_Void
Comment: I suspect the concept of computers would stay a concept until they got over their disorder.
Comment: People didn't invent zero, they discovered the fact that there is a lack of a thing
Comment: @Graham: they can say they can't lift an elephant ;D
Comment: @user6760 That doesn't answer the question.  The question is explicitly phrased as "how many", for which the answer has to be "none".  Even if they could reply another way, mentally they know the answer is "none" and they have to kill themselves.
Answer: Computers don't actually have 1s and 0s
Technically, computers use high/low electrical charge to transmit and store their information. We use one and zero since that can easily conceptualize and represent truth values, numbers, and ascii values. Instead of values going from 0 to 15, 4 bits would go from 1 to 16. Because of this all computer systems will be one indexed, instead of zero indexed. Computers would be able to do everything they can currently. But instructions might be tuned so that all bits are at least one high or low in a string, so there is no zero interpretation of a string.
One thing that computers won't be able to do is anything you can't do in this universe. A few examples:

A computer counts inventory of a store, the store then runs out of stock of one item. The computer then has to display, "Null" which means no data is available. If even guessing this means that there is nothing is a problem, then the system also needs to randomly display "Null".

A computer programs a brake to multiply the resistance it applies by distance to an object. A function returns the distance between two objects. The function must again return "Null" which means all functions that interact with it must accept "Null".

Any math function that uses zero will not work, instead you will need to use a function that determines if a zero occurred and branch to do the math properly.
Comment: Rather than "NULL" which is synonymous to "zero" or "nothing" it would return "NaN" meaning not a number or "undefined".  This is what computers typically return when you divide by zero.
Comment: You can also think of it as "true" and "false".
Comment: Seems like in order to "use a function that determines if a zero occurred" the programmer has to acknowledge that it exists. Even if the _code_ doesn't contain zero (e.g. replacing "if A-B==0" with "if A==B") it seems like explicitly handling that case requires the programmer to consider zero. I dunno - maybe in OP's world, math has evolved such that everyone is taught that you simply can't subtract a quantity from itself; it's an illegal operation you're checking for, not zero. Or maybe all software depends on lower-level libraries that were written by programmers who went mad in the process.
Comment: One could argue that null as a concept evolves from zero so maybe computers wouldn't display null. I don't know what computers would do instead though, maybe an empty string but that also feels like a related concept.
Comment: Good answer pointing out that 1 and 0 is high and low voltage. However, a little UX can solve the display problems. For no items, the computer can display a blank or `none`; having none of a thing would be familiar. For the distance, it could say `touching`. And since their math has no concept of zero, they would simply get an error; `1/0` gets an error in most calculators because our math doesn't account for discontinuities.
Comment: Your first bullet point highlights the problem with the whole premise. Do these people just kill themselves at the sight of an empty box?
Comment: Unfortunately a lot of the math that is the basis of such things as formalizing mathematics in an arbitrary base such as 2, 10 or 16 requires multiplying and adding 0s. Half adders for instance require 0s for the single digit arithmetic to work out.
Comment: @Nosajimiki depending on the language Null NaN and undefined are different types, constants or are treated equally. I use "Null" to generally mean no data.
Comment: A set theory "zero is merely an abstract" may work for hand-waving in a book, but for real computers definitely think 0 means "no change". They use offsets all the time and 0 meaning "starting from here, no up places" is a big deal.
Comment: How do you develop the concept of multiplicative base without zero? No multiplicative base, no binary.
Comment: @Joshua to translate a set of bits to numbers, use this algorithm. Set variable base to 1, and set result to 1. Then, Iterating over the bits, if the bit is true, add base to result, and then multiply base by 2. Return result.
Comment: @CharlieHershberger NULL means no data which is a concept of nothingness, but this isn't the same as NaN,  NaN is an error code for an illegal mathematical operation. While NULL says nothing is there, NaN says that something is there, but it is incomprehensible like an imaginary number or a divide by zero is to us.  From the perspective of your living people in this setting, 0 would have to be acknowledge as a thing that exists to avoid the acceptance that nothingness can exist. Its a think they hit in math, but when they do they just don't know what to do with it so they call it an error.
Comment: "the store then runs out of stock of one item". I'm reminded of the time a French supermarket system (developed by us) crashed when the stock level of an item went negative. They had sold more of X than they had in stock. Turned out the product was live fish, and they were breeding in the tank.
Answer: Before the invention of algebra, advanced math was done by moving tokens and geometric shapes around: not by equations. Geometric math is fundamentally different than algebra in a lot of ways.  For starters, there was no such thing as "negative" or "zero" since all math was based off of physical things.  Instead, all math was seen as more like vectors. You move a value one way or another, and you end up with a value based on how these manipulations compound based on directionality.  So, if you you needed to solve something like Profit - Lose = Net, you would do this by placing down a token and moving it left or right to represent the opposing values. So, you would move your token right a positive number of Profit spaces, and then left a positive number of of Lose spaces.  If you equation would be 300-500 = -200 in algebra, in Geometric math, you avoid the concept of negative by saying something more like 300 profit + 500 loss = 200 loss.
However, in Geometric math, you also can not have a zero, because is not a tangible thing you can represent with tokens or shapes. But you can have procedures that equal zero like 1 left + 1 right.  So, zero existed only as a complex number, but not as a simple number. This should not be all that unfamiliar of a concept though since we still have all sorts of numbers that can only be expressed by a complex number like 1/3.  And where Zero itself is concerned we have still yet to figure out how to represent it in algebra in every situation.  "what is 3/0?" It is not Zero or infinity or any other thing we recognize as a number.  If you divide by zero, it returns "Not a Number" or "undefined" in most systems.
So can you make a modern computer work this way? Technically, yes. Computers at the most basic level are based on the Turing machine which work by tracing through possible values left and right.  Binary shown as 1s and 0s is just one concept that can represent that.  But you could just as easily name binary values as up and down or left and right, and it would all still work exactly the same.  That said, geometric math can't solve all the same problems algebra can solve; so, even if the computers themselves are Turing Complete, the people programming them will not be able to solve all the problems with them we can.  This would limit their software quite a bit. But they could certainly still do some interesting things when you consider that thing like the Antikythera mechanism was built by a civilization still using geometric math.
Answer: tl;dr: Nothing would change.
Misconceptions
There are several misconceptions in your question:

The mathematical concept of an operation on a set having an identity element has nothing to do with the philosophical concept of Nothingness, so the taboo does not prevent us from inventing this concept.
Computers don't use Zeroes. They use two symbols whose names are utterly irrelevant.
Actually, they don't necessarily use two symbols. Binary computers use two symbols. Ternary computers use three, decimal computers use ten.
Actually, that's only digital computers. Analog computers operate on continuous domains, so they don't even have a finite set of symbols at all.

Equating 0 to "nothingness" is purely a human interpretation of the symbol 0. There is nothing inherent in either the symbol 0 or the mathematical concept of Zero that equates it with nothingness.
Zero in algebra
E.g. in Algebra, Zero is simply a name we attach to an object that obeys certain laws.
For example, a monoid is defined as an ordered pair (S, ω) of a set S and an operation ω, which satisfies the following laws (assume a, b, and c are elements of S):

Associativity: (a ω b) ω c = a ω (b ω c)
Identity Element: There exists a unique element e for which the following holds for all a: a ω e = e ω a = a

If these two laws hold, then we call (S, ω) a monoid and call e the identity element of (S, ω).
And that's it. Everything else we put on top of that is just an interpretation. For example, in the group (ℝ, +), we call the operation + "addition" and the identity element "zero", but those are just labels we attach to those mathematical concepts.
If we had a taboo on "nothingness", we would still eventually invent this concept … we just wouldn't think of it as "nothingness". It would probably take as a while longer to invent it, and it might take a convoluted meandering path to get there, but in the end, we would find it.
This actually happened!
But the most damning evidence that this would not be a problem is that this is actually what happened. The foundations of Computer Science laid down by people like Alan Turing, Alonzo Church, Haskell Curry, Kurt Gödel, Gottlieb Frege, and others, only talked about operations on natural numbers, which do not include 0.
In other words, computers were invented without using the number 0.
… multiple times!
Obviously, those logicians knew about Zero, they just didn't use it for building the foundations of Computer Science. But, there is an example of a computer built by people who didn't even know about Zero:
The Ancient Greeks had no Zero, yet they built the Antikythera mechanism, one of the oldest known computers. (In this case, a mechanical analog computer.)
Comment: Whether the set of natural numbers includes zero or not is a matter of convention. For example, when I was at university, we used $\mathbb N$ for set with zero and $\mathbb N^*$ for the set without zero. And the ancient Greek did [use a positional number representation system](https://en.wikipedia.org/wiki/Ptolemy's_table_of_chords) when they absolutely *had to*, complete with a symbol for an empty rank. (And for them even one was not really a number!)
Comment: A bit of a nitpick-- $(\mathbf{R},\times)$ isn't technically even a group-- 0 has no inverse for multiplication (defined the usual way, at least). $(\mathbf{R}-\{0\},\times)$ is, but the identity element is 1, not 0 (and 0 explicitly is not even a member of the group). I think you probably meant to say $(\mathbf{R},+)$, which does have 0 as the identity element.
Comment: I can't agree that equating zero with nothingness is just interpretation. There's certainly a parallel to an addition identity and doing nothing. Even more so because it is the other way around: mathematicians came up with the intended interpretation before formalizing math.
Comment: @AlexP In fairness, while I don't agree with OP, I think there is a plausible steelman in that the lambda calculus doesn't really have a zero as such. Or rather, the Church numeral that represents $0$ is a function which really has genuine meaning, and has no connotations of "emptiness" unless you choose to view it that way. In the lambda calculus, everything has substance, since everything is viewed as an *operation* rather than a *thing*.
Comment: (I bumped that up to an answer: https://worldbuilding.stackexchange.com/a/222906/13796)
Comment: @elduderino: You are right. I mixed up monoids and groups, and addition and multiplication. It's been 25 years since school :-D
Comment: @PasserBy: The exact same laws also apply to the monoid (ℝ, ×) with `1` as the identity element. Here, we *don't* equate `1` with "nothingness", even though the same laws apply to it. I am not saying that the idea of addition being equivalent to counting and `0` being equivalent to nothing didn't speed up the development of algebra. In fact, I explicitly acknowledge that in my answer. But the discovery of the concept of `0` being the identity element of addition is *inevitable*, regardless of whether you think of it as nothingness or not, simply because it is *actually the same thing* as `1` …
Comment: … being the identity element of multiplication, which does not require thinking about nothingness at all.
Comment: _"The exact same laws also apply"_, only if you treat it as a monoid. You could possibly argue that the nothingness of 0 is even more prominent with the ring of integers.
Comment: To expand on @AlexP I'm quite sure that in foundations of CS zero was included in natural numbers. Zero not included in natural numbers is rarely used outside of number theory AFAIK...
Answer: Others have gone into how the computer guts would be designed, but what about the interface? Surely you need to display a zero!
zero doesn't have to be nothing
Charlie Hershberger brought up some interesting user interface examples which made me realize the ethnocentric premise in the question; that zero is nothing. A terrifying void.
Does it have to be? Can we map what we use zero for onto comfortable tangible concepts?
$\emptyset$ : zero is an empty bag
What if your inventory system has no stock of an item? Surely they can count and understand the idea of having none of a thing or they wouldn't live very long.
If I have a shelf with 2 apples and take 2 apples off the shelf, I have an empty shelf of apples. This is the empty set: $\emptyset$. It isn't nothing, it is an empty shelf. An empty shelf is a comfortable concept.
But what does it mean for there to be none of nothing? Or none of everything? For that matter, what does "5" mean? How do you have 5 of nothing? You have to have 5 of something! Even if that is just "5 things". "5 things take away 5 things" is "no things": $\emptyset$.
Watch Numberphile's What is a Number? for a bit more on numbers and set theory.
$x = y$ : zero is balance
What if they're using a calculator and subtract 6 from 6?
$6 - 6 = 0$. We can rewrite that as more generally as $x - y = 0$. Nothingness. They cancel each other out.
We can also write it as $x = y$. Balance and equality.
If we're weighing two items we could say "the difference between their weights is 0" or we could say "their weights are equal". They are in balance.
zero is the center
Look at a number line.

Where is 0? It is at the center. Endless possibility stretches off in either direction.
If we expand into two and three dimensions we add more zeros: $0,0,0$ is the center of all space (we're talking psychological philosophy here, astrophysicists sit down).
zero is togetherness
What if we measure the distance between two objects and find it to be zero? Is the distance nothing?
Or are they touching? A perfectly comfortable physical concept.
zero is the beginning and the end
If your distance traveled is zero, you are at the beginning.
If the distance remaining to be traveled is zero, you have arrived.
infinity is our zero
Our own computers have trouble with infinities. Yes, infinities, plural.
Mathematical systems are a set of internally consistent rules which we decide on. Sometimes to make them internally consistent we need to define certain expressions as undefined.
Our everyday math declares that $\frac{x}{0}$ is not a number and a lot of other things having to do with zero. Zero solves some problems, but it introduces more.

Zero is a perfectly good number and you ignore it at your peril. The problem is, it's a dangerous number and a lot of things can go horribly wrong with zero. And because it is a slightly more nuanced number you have to be more careful with how you handle it. -- Matt Parker

If you put $\frac{1}{0}$ into most calculators you will get an error. Or maybe infinity, which is even less correct than getting an error. $\frac{1}{0}$ represents a discontinuity in the number line.

If you try to solve for it from the right, you get positive infinity. If you try to solve it from the left, make x a really big negative number and you get negative infinity. The answer diverges, it is both positive and negative infinity. See Problems With Zero for why
Our common everyday math does not have a concept for this. Our brains struggle with infinity, let alone something as simple as $\frac{1}{0}$ having multiple infinities at once. We don't like the idea of a question not having one answer, and we struggle with the idea of counting and never stopping. You probably won't kill yourself over it, but most people would struggle to even know how to write the answer down.
$$\lim \limits_{x \to 0^-} \frac{1}{x} = \infty^-$$
$$\lim \limits_{x \to 0^+} \frac{1}{x} = \infty^+$$
So we just say error or not a number or undefined. When we write computer programs we make sure to check for divide by zero errors. You can't divide by zero because we said so; it's just too hard.
Their computers would be no different. Their math and vocabulary and analogies would be built around the idea of avoiding nothing, like we avoid infinities, and this would seem perfectly natural to them.
Zero is a problem. We choose to stare into the void and sweep it under the rug.
Answer: Computers based on the lambda calculus.
The history of general-purpose computing machines in our world, by what amounts to historical accident, specialised primarily in the direction of Turing machines; these are inherently discrete and skirt a fine line next to forcing you to confront what it means for something to be empty. But there's a hypothetical timeline where Church won, and the lambda calculus was the primitive. In such a world, programs aren't defined by state machines, but instead are defined by composition of terms. No lambda-term is "empty": emptiness isn't even part of the model of what it means to be a lambda-term. The number $0$ is conventionally expressed in the lambda calculus as the corresponding Church numeral which is essentially the concept "apply your first argument $0$ times to your second argument"; i.e. it is the function $(f,x) \mapsto x$. There's no reason anyone needs to contemplate nothingness here: this is a genuine function which really does do something "positive" and useful! (For completeness, the number $2$ is represented as the concept "apply your first argument $2$ times to your second argument", i.e. the function $(f, x) \mapsto f(f(x))$.)
Functional programming languages are often inspired, directly or indirectly, by the lambda calculus. For example, LISP is quite a lot like the lambda calculus in spirit. At one point, we even had computers for which LISP was the primary abstraction. I don't know quite how their hardware was implemented, but I wouldn't be at all surprised to find it was possible to represent a LISP machine entirely in hardware without needing to consider what "emptiness" was.
Answer: Modern computers do not naturally handle numbers as decimal digits, they use a binary encoding more naturally suited for handling with the electronic logic they are built on, based on a fixed length sequence of bits. For programmers working close to the hardware, even this is often too awkward to work with, and it is converted to/from octal or hexadecimal instead.
Why these and not decimal? Because the digits match up in these representations, but not with decimal. Each hexadecimal digit corresponds directly to 4 bits, an 8-bit or 16-bit unsigned integer has a maximum value of exactly 0xFF or 0xFFFF, etc. In decimal, those are 255 and 65535...not quite so obvious. Floating point numbers are even further removed from decimal, and can't even exactly represent quantities as simple as "0.1".
All this typically has to be hidden from normal users by the programmers, converting to and from decimal, applying artificial limits, carefully rounding results, etc. The presentation form doesn't need to be a zero-based decimal positional representation, it could be something like Roman numerals, or a bijective numeration (a positional system that starts numbering with 1, with no zero digit and the quantity zero being represented as an empty string). Only the programmers need be aware that the machine has a bit pattern for "nothing" that it considers as valid as all the other bit patterns. They may consider it just a quirk of the encoding or a convenient special value. If they lack the mental flexibility to do even that, I doubt you have to worry about them building computers.
Answer: Analog computing!
The idea of the paradigm is to use some usually-continuous aspect of physics to do computation for you; I guess one of the simplest examples could be a sand timer or water clock, but the slide rule is probably the analog computing device we're most familiar with today.
Analog computers can work without anyone needing to think of zero - in fact, since continuous quantities never really tend to hit zero in real life, analog computing is probably the paradigm that was born to serve these people.
You can use bespoke analog computers to solve a large number of specific problems (e.g. solving various kinds of differential equations for innumerable practical purposes). You can make a "programmable" analog computer by essentially having a mechanism that switches between a number of analog computers (or chains together a number of components of an analog computer).
I'm afraid this is not at all my area of expertise, but the Wikipedia article contains a great many examples that may give you inspiration. For a detailed introduction, the Omega Tau podcast did an episode a few years ago.
Comment: *"Continuous quantities never really tend to hit zero in real life":* The voltage supplied by the outlets in my house passes through zero one hundred times per second.
Comment: *Through* zero, sure, but can you tell me when it happened? The strong version of the intermediate value theorem doesn't hold in all constructive formulations of analysis, remember!
Answer: Inventing a zero certainly was a big progress for mathematics in our world, but it's not strictly necessary to have working arithmetic.
$\def\X{\mathrm X}$
While we are usually using digits $0$ to $n-1$ in our base-$n$ systems (like base-10 or base-2), one can build a positional notation (aka "base-$n$-system") using digits $1$ to $n$.
Just as an example, with base $10$ (written $\X$ here), the first natural numbers might be written like this: $$1, 2, ..., 9, \X (=10), 11, 12, ..., 1\X (=20), 21, ..., \\ 99, 9\X (= 100), \X1 (=101), ...,
 \X9 (=109), \X\X (=110), 111, ...$$
I've first read about this in the article Sennula nombrosistemo by Bertilo Wennergren (in Esperanto). I guess it's also called bijective numeration, but I didn't know this term until now.
With a base-$2$ system (which we'd use in computers) you could have digits $1$ and $2$, and you'd count like this:
$$1, 2, 11, 12, 21, 22, 111, 112, 121, 122, 211, ...$$
This works when you can have a variable number of digits, but for efficiency you'd also want to have a fixed width representation (in our world, done by left-padding with 0). I don't know how that might work here – maybe we'd need a third digit just for the padding, or need to additionally keep track of the number of actual digits. Or we'd go for a higher-base directly.
Answer: Making a computer without zero is possible, after all universal Turing machine has no concept of numbers and can perform all possible calculations.
However, it will be impossible to build an actual machine while evading the concept of zero. Anyone who works on engineering will eventually reach a point where they will have to deal with 0. In fact, your society will not function far. How many steps are needed to access to your home can have an answer of 0, whether it is represented arithmetically or literally as no steps.


Keeping track of windowhandles with Selenium in Internet Explorer 11

Question: We are working with Selenium webdriver to make UI tests for Internet Explorer 11.
In the tested webapplication there are several screens popping up. In several tests we end up with three browserswindows, so also three Driver.WindowHandles. To switch from one WindowHandle to the other we expected that Driver.WindowHandles would be sorted like the oldest windows first and the newest windows last. But this is not the case: It is totaly random! Because a windowhandle is a GUID we ended up creating a dictionary with the WindowHandle GUID as key with the value of the type of page which is loaded in the browserwindow.
But this also results in maintaining the dictionary when closing a window for instance.
This seems to be a lot of work for such a simple matter. Is there a better solution for this?
Answer: Troubles with handling multiple windows is one of common traps.
Elemental Selenium has great explanation (and more interesting articles about common traps).
Catch is: order of windows is not guaranteed between browsers (it is not specified by standards). Google will give you many posts about this trap.


How to transfer world saved on linux desktop to minecraft server on linux computer using linux commands

Question: So i have been trying to transfer a minecraft world save from my linux desktop to my linux minecraft server but have no idea how to move from desktop directory to linux server directory. I am also using amazon aws to host my minecraft server. Thanks.
Answer: First, Shut down the server. If you open the folder the server is in, there should be a folder called world. Get the world file that you want to use for your server, then drag that into the server folder. Then name the world you want to use world. So it replaces the unwanted world. Then relaunch the server.


If ㅆ meets the consonant ㅅ, will the resulting sound be a double " ss "?

Question: i was just wondering if its okay to transliterate or pronounce it to kuossumnida 그었습니다 or should it sound like kuot sumnida with the t stops ? or is it okay if this two ㅆ+ㅅ = ㅆ or double ss ? hence it will sound kuwos sumnida not kuot sumnida and could you please tell me the name of the rule of this sound change . thank you ;)
Comment: Briefly put, there will be no hard stop after the ㅆ when followed by ㅅ.
Comment: thank you so much :) no name for that rule ? could you give me another word :) that has this kind of sound change . please and thank you .
Comment: The easiest and most prevalent example is 있습니다 (to have, to be). I do not know of any official name for this rule however. It is sort of like the rule that "ch" has a sound change in English. It is just "the rule."
Comment: thank you ever so much for taking the time :) to comment here yeah........... i was attempting to edit my comment since i would like to inform :) you that i want a word that has ㅆ double shiot 쌍시옷followed by a 시옷 and not a stem + formal high suffix sumnida . i see :) now i am even more curious about this rule ;) i mean the name of the rule in korean language
Comment: ㅆ followed by ㅅ in the same word is always a continuous 's' sound
Answer: 습니다 was actually historically spelled 읍니다 when it was followed by a ㅆ final until 1988.
It was changed to 습니다 in the reform of 1988. The reason was that there was no reason to differentiate between 읍니다 and 습니다, because no one did in real life.
As for ㅆㅅ or ㅅㅅ being pronounced as the same sound as ㅆ, is nowhere to be found on the Standard Pronunciation Rules. Actually, 했습니다 should be pronounced as [핻씀니다], according to those rules. That's because the rule states that the finals preceding a consonant must be pronounced as one of these seven consonants: ㄱ,ㄴ,ㄷ,ㄹ,ㅁ,ㅂ,ㅇ.(표준 발음법 제4장 제8항)
So very strictly speaking, 그었습니다 pronounced like [그어씀니다] is not the standard.
Comment: love the *Bongo* ad!
Comment: thank you so much yes yes i know that :) rule :( hmm.. actually i saw that rule from an app called rieul the rules says 시옷  following받침with ㄱㄷㅂ sound is pronounce as 쌍시옷 ㄷ,ㅌ,ㅈ,ㅊㅅ,ㅆ+ㅅ = ㄷ + ㅆ like 헛소리 must be pronounce as 헏쏘리 instead of 허쏘리 where the ㄷ stops is not heard at all like it was assimilated or something :( thank you so much
Comment: but does that mean someone is pronouncing it like that :( even if its not standard  i mean would it be  okay for me to pronounce it like that since it flows better than with a ㄷ stop :) or ???? maybe i should still pronounce the ㄷ + ㅆ which is the standard one . thank you for helping me ;) maybe that question was stupid so :( i will apologize now . i am terribly sorry for my innocence . and thank you for sharing your knowledge ;)
Comment: that page was really nice i wanted one of those . do you happen to have all the pronunciation rules 음소변동 on that website . please send me the link :) thank you mujjin :)
Comment: @majutsushimika That page I linked to is the official page of the Institute of Korean Language. So it *is* the standard source to look up sound change rules. Anything that is not listed on that page is not the standard.
Answer: I'll go out on a limb and claim that MujjinGun's answer is a bit misleading, while technically correct.
That is, if the standard requires 그었습니다 to sound as [그얻씀니다] (with a ㄷ sound in the middle), then I think it is either the error of the standard, or maybe the actual pronunciation of Korean has changed to such a degree that the standard is no longer an accurate representation of the real language.
It seems that having a ㄷ+ㅅ(ㅆ) cluster should create a sound similar to "tsu (つ)" in Japanese.  But I don't think I've ever heard that sound in Korean.  (Well of course I could be wrong, because if I don't use that sound then my brain will filter the sound out even if others use it, but I think someone would have noticed and remarked on it.)  Also, Koreans learning Japanese frequently have a difficulty pronouncing the "tsu" sound, which shouldn't be the case if the sound was actually used in Korean.
So I think it is always pronounced as [그어씀니다] in real life.
Comment: yeah つ in japanese is like double of kk or tt けっこう/たった the tsu here called 促音anyway :) there is another word in korean conjugated to 지마 and the verb is 늦다 but if we conjugate 늦지마 another case of two 받침 so when this ㅈ+ㅈ = ㅉ yes ? so there is no ㄷ stop here or would this be same like ㅆ + ㅅ = ㅆ  and as usual the ㄷ somewhat disappear and it was like um..... assimilated or what ? like when this two ㅆ+ㅅ  meet and sounds like ㅆ without the ㄷ stop of course
Comment: if this was any part of the rule i would like to know its name in korean :) or whatever they named that rule ;) i am so curious i mean if it did exist . if not then i will pronounce it as 경음화
Comment: The standard requires "ㅅ+ㅆ=ㄷㅆ" but practically nobody speaks like that; **it's assimilated into one "ㅆ."** It's a bit shocking to me how the standard differs from the current use.