Rationale for fitted vs residuals plot

Question: Why does examining fitted vs residuals plot help us determine whether there is heteroskedasticity or not? Could someone give me a detailed theoretical rationale for this test? Does the randomness of residuals around the horizontal line y = 0 guarantee homoskedasticity, or does it just support the presence of it?
Comment: There are no guarantees in statistics ;-).
Comment: Similar posts:https://stats.stackexchange.com/questions/103466/heteroscedasticity-in-residuals-vs-fitted-plot, https://stats.stackexchange.com/questions/182316/interpretation-of-residuals-vs-fitted-plot, https://stats.stackexchange.com/questions/434877/how-to-interpret-residuals-vs-fitted-plot, https://stats.stackexchange.com/questions/155513/interpreting-linearity-in-residual-vs-fitted-plot, https://stats.stackexchange.com/search?q=fitted+resid*+plot+answers%3A1+-mixed
Answer: In my opinion "examining fitted vs residuals" is a graphical alternative to the Box-Cox test When (and why) should you take the log of a distribution (of numbers)? which can help to evaluate the hypothesis that the variability of residuals is or is not linearly related (sympathetic) to the level i.e.the fitted values of the series.
IFF you are analyzing time series or spatial data there is an additional scheme available....
"examining the plot of the residuals over time" is a graphical way of assessing possible deterministic change points in the error variance which suggest periods of time where the variance of the errors changes significantly. See a formal test for this here http://docplayer.net/12080848-Outliers-level-shifts-and-variance-changes-in-time-series.html
Finally if you don't treat one-time anomalies as just that you can often mis-analyze the data as was done with the classic INTERNATIONAL AIRLINE PASSENGER DATA example presented by Box and Jenkins in 1964 https://autobox.com/cms/index.php/blog . A few anomalies at the highest level of the series skewed the Box-COX test to conclude the higher levels meant higher model error variance which is not true in general. https://autobox.com/pdfs/vegas_ibf_09a.pdf has some very illuminating and specific details on the AIRLINE SERIES data.
Box & Jenkins conclusion (without suggesting viable alternatives) that you need to take logarithms was roundly criticized in the respected literature by other time series statisticians particularly Professor Chris Chatfield from Bath University.
Comment: Thanks for the answer. I'm still confused as to why the graph is an alternative to the Box-Cox test. How is this possible?I guess in another way, what I am confused about is that why is the randomness of residuals around the horizontal line y = 0 indicate/suggest that there is homogeneity?
Comment: randomness around the residuals is all about the expected value . randomness of local error variance speaks to the second moment . If the cariance of the errors is linearly associated with the level of the expected value THEN log's would be suggested. If the varaince of the errors DOUBLES t some point this suggests Weighted Least Squares .
Comment: @Rainroad if you wish to have a chat session ... will try and help
Answer: Heteroskedasticity means quite general that the residual variance is not homogenous, i.e. depends on groups or some other variable. Note that, according to this definition,

if you find that var(res) ~ fitted, you clearly have heteroskedasticity
However, if you don't find a relationship between var(res) ~ fitted, you could still have heteroskedasticity, for example when testing var(res) ~ predictor1. In principle, you have to test against all possible predictors to exclude the possibility of heteroskedasticity.

In general, it is therefore advisable to plot residuals against all predictors and grouping variables (after all, when you model heteroskedasticity, you can make it also dependent on particular variables). This, however, means that you have to do many plots in a multiple regression. If you want to do only one plot var(res) ~ fitted is a good compromise, because fitted will be correlated with all predictors that have an effect, and are therefore of particular interest in an analysis of heteroskedasticity.
Comment: oh this makes sense. thanks

Rationale for fitted vs residuals plot


Are Latin legal terms still used?

Question: The Latin legal term "ignoramus" is present within legal dictionaries for when there is not sufficient evidence. Are terms like this still used, or does a jury resort to plain English when endorsing a bill and use "not found" in the place?
Comment: Yes, both in civil and common law that is often derived from Roman law, such as: [Ignorantia juris non excusat](https://en.m.wikipedia.org/wiki/Ignorantia_juris_non_excusat).
Answer: yes
Many are. For example, if a lawyer appears in a court he is not on the bar for, he appears pro hoc vice.
The most common one you'll hear in a german court is lawyers using in dubio pro reo in their plaidoyer when they want to claim that there is not enough evidence to convict their client.
Answer: Yes
However, in Australia there has been a dedicated push to reduce the use of Latin terms to those that have entered the general English vernacular or that refer to specific procedures in the legal system.
So it's OK for a lawyer to use de facto or certiorari but frowned upon (as in, the judge will usually say "In English, please") to use de die in diem.
Answer: Latin Terms Used In English Legal Terminology
I have never seen the specific Latin legal term ignoramus used in American legal jurisprudence.
But, all sorts of Latin and Latin derived legal terms are common in American legal jurisprudence and probably even more common in English and European jurisprudence (and, of course, Latin is still the primary language of Roman Catholic canon law, a discipline that still have active practitioners, even in 21st century Denver, Colorado).
Here are 112 common examples that I see used regularly in the law (some or all are arguable English loan words rather than true direct uses of foreign terminology from a linguistic perspective, others are arguably not specifically legal in nature). Sometimes true loan words persist because the "plain English" preferred substitutes are less widely understood or have a meaning less well established in precedent.
per diem (the amount of interest that accrues per day, also a lump sum allowance per day for out of pocket expenses in lieu of reimbursement based upon receipts).
nolo contedre (no contest to criminal charges)
ab initio (anew from the beginning)
a priori (in advance)
ad infinitum (and so on forever)
affidavit (a sworn statement)
arguendo (for sake of argument)
caveat (limitation)
caveat emptor (buyer beware)
alter ego (disguised secondary identity)
ad hominem (an attack on the person making an argument rather than the argument itself)
ceteris paribus (all other things being equal)
contra (against)
de novo (without deference to previous proceedings or decisions)
dictum (statements of law made when not necessary to resolve the present case that are not precedents for case law purposes)
stare decisis (the doctrine that precedent should be followed by courts)
subpoena duces tecum (a legal document demanding the production of documents or things)
ergo (therefore)
erratum (a list of error corrections)
et seq. (abbreviation of et sequens, meaning "and the following ones". Used in citations to indicate that the cited portion extends to the pages following the cited page.)
imprimatur (ratification)
in extremis (in extreme circumstances)
in flagrante delicto (caught in the act)
mittimus (the written statement of a finally determined criminal sentence)
in forma pauperis (as a poor person with a request for a waiver of fees)
in rem (limited to or pertaining to property)
in pari delicto (having joint responsibility)
in pari materia (to be interpreted together with other parts of the same source material)
in re (in the matter of)
in situ (in place)
status quo (the pre-dispute or pre-event or current state of things)
infra (above)
supre (below)
innuendo (rumors)
jurat (the portion of a notarization containing the oath or acknowledgement itself)
lacunae (unaddressed point or issue)
lex loci (jurisdiction by virtue of the location)
lis pendens (notice of pending litigation, usually recorded in real estate records)
N.B. (abbreviation for "nota bene" meaning "note well").
per capita (per person)
per stirpes (per line of inheritance)
per curiam (by the court as a whole without attribution of authorship)
per se (something that is automatically or definitionally true)
pro forma (for form, sometimes financial projections estimated since they anticipate the future)
inter vivos (during life, usually in relation to a gift or a trust)
C.V. (abbreviation for "curriculum vitae" which is a resume of a learned professional such as an expert witness, or scholar).
pro tem (temporarily)
quantum meruit (an amount owed notwithstanding a lack of a contract)
quasi (similar to but not the same as)
res (the thing, often referring to the assets of a trust)
situs (place)
sua sponte (without prompting and without a request for action)
sub nomine (under the name of, usually used when there is a name change in mid-litigation)
sub silentio (a ruling or agreement made without explicitly saying so)
supersedeas (a bond offered in lieu of other remedies)
ultra vires (beyond the authority of the person acting)
veto (refuse to allow to go forward)
vice versa (the other way around, i.e. in reverse order)
viz. (abbreviation of "videlicet" which means "namely")
subpoena (a order to testify at a time and place)
modus operandi (distinctive customary or habitual technique)
in personam (acting on or imposing obligations upon a person)
forum non conveniens (a doctrine providing that a court may decline to hear a case over which it technically has jurisdiction because there is another more convenient forum in which to hear the dispute).
nunc pro tunc (retroactively to the relevant date)
et cetera (abbreviated etc., meaning and so on).
ad valorem (in proportion to value, usually for property taxes)
ad hoc (in response to the circumstances rather than as part of a plan)
amicus curiae (a brief filed in a case by a non-party as a friend of the court)
guardian ad litem (a guardian of a litigant for purposes of litigation)
actus reus (the act which must be taken to commit a crime or tort)
bona fide (genuine, often in the sense of not acting as a straw man, not aware of wrongdoing, and not acting on behalf of an interest part)
alibi (the defense of being somewhere other than where a crime or act was committed at the time)
corpus delicti (the facts showing that a crime was committed)
res ipsa loquitor (a doctrine that presumes liability in cases where control of the proof is predominantly with the alleged tortfeasor)
res judicata (a doctrine that bars re-litigation of civil disputes)
pro se (representing oneself without a lawyer)
pro hoc vice (a lawyer temporarily licensed outside his or her jurisdiction of admission for a particular case)
pro bono (free legal representation)
a fortiori (something is true in the stronger case because it is true in the weaker case)
testator (male or person who writes a will)
testatrix (female who writes a will)
executor (male or person who administers a probate estate)
executrix (female who administers an estate)
ipse dixit (a statement that is true solely by decree rather than with justification)
mens rea (intent)
scienter (specific knowledge of one's own wrongdoing)
mea culpa (a concessionary or appeasing confession or admission)
locus (place)
in limine (a motion when brought on the eve of trial to adjudicate evidence issues)
in loco parentis (in the place of a parent)
de facto (in reality)
de jure (as a matter of law)
certiorari (discretionary supervisory review of an inferior tribunal or quasi-judicial body)
quo warranto (an action to determine the validity of an appointment)
mandamus (a action to order a public official to take a non-discretionary action)
habeas corpus (a suit over who should have custody of a human being, usually an adult detained by the government on criminal or terrorism charges)
ex post facto (having retroactive effect)
ex post (after the fact)
ex ante (pre-dispute, before the fact)
ex parte (action in court or communications with a judge outside the presence of the adverse party)
in camera (private review by the judge without allowing review by all interested parties).
sine die (termination of a session, usually of the legislature, without an intent to reconvene in the same session)
ipso facto (by definition or by virtue of holding a position)
nexus (a legally relevant connection)
post mortem (after death)
prima facie (proof that is sufficient if not contradicted by other evidence)
quid pro quo (one thing in exchange for another, a direct barter)
inter alia (among other things)
ibid (abbreviated "id.") (same citation as the previous one used).
et al. (an abbreviation for et alia (neuter plural). But it can also be an abbreviation for et alii (masculine plural), or et aliae (feminine plural). This phrase means "and others.")
i.e. (abbreviation for id est, meaning "that is")
e.g. (abbreviation for the Latin phrase exempli gratia, meaning "for example.")
Terms From Other Languages
A few legal terms that are loan words are not directly Latin in origin. For example:
replevin (a lawsuit to recover physical possession of tangible personal property, from Old French).
Yiddish is not infrequently used in American legal writing, although rarely as a term of art. More frequently it is used to add colloquial color to legal writing.

Are Latin legal terms still used?


iOS Xcode distribution cant upload App for review - no access

Question: I am a developer part of a team and I can't upload our app to iTunes Connect from Xcode.
Error from archive:

I have a company developer account (ocularLogic). I am part of another company as well where I have an admin role. I am uploading the app with ID 1446905085 for the client from my computer using Xcode. I have downloaded provisioning profiles and key chain access for development so why can't I upload the app????
Answer: I was able to upload successfully. The trick is to be added as a user to both the "Developer Account" AND "iTunes Connect". I was part of the developer team to create profiles, ect but I was not added as a user to their iTunes Connect. I would assume they were one of the same but I guess not.


Do Dpkg and apt-get install dependencies?

Question: I've been wondering, is there a way to tell dpkg or apt-get that when I want to install a package also install all the dependencies it requires? I installed a package using dpkg but it complained about some dependency issues so I had to manually search one by one, is there a better way to do this?
Comment: dpkg does not handle dependencies, it's a low level package management tool.
Answer: apt-get or aptitude will install all the dependencies of a package. According to apt-get man page

All packages required by the
  package(s) specified for installation
  will also be retrieved and installed.

Even if you want to install a package from source you can install its build dependencies using apt-get. Use apt-get build-dep for that purpose. Again from apt-get man page:

build-dep causes apt-get to
  install/remove packages in an attempt
  to satisfy the build dependencies for
  a source package.

For example if you want to compile gcc you will need all the build dependencies for successfully compiling gcc. So you use sudo apt-get build-dep gcc. This will install  all the packages required to build gcc from source.
Answer: Dependencies should be installed by default with apt-get. You might also want to read the answers for this question: Installing suggested/recommended packages?.
Comment: And if it doesn't?! I run this command: "apt-get install --no-install-recommends ubuntu-desktop, And it says The foloowing packages have unmet dependencies: checkbox-qt, eog,gedit,....... too many packages.
Answer: If after using dpkg to install a package it tells you that there are missing dependencies, you can run apt-get -f install to install any missing dependencies on your system.
Answer: If you're looking for a tool that will install a downloaded (ie. non-repository based) package including dependencies, look at gdebi (the GTK UI) or gedebi-core (the command line tool).


How to schedule a Windows task on wake?

Question: I created a task in Task Scheduler to run at system startup, and it works great. However, I want to change it to run every time Windows wakes from sleep and I cannot figure it out. The relevant options available to me are at startup (currently), at log on, on an event. Perhaps I need to select on an event and find an event that happens when the computer wakes?
Comment: If the task is not starting after waking up, try checking "Run task as soon as possible after a scheduled start is missed" and see if that helps. Other than that, review existing tasks to see if there is an On Event trigger that will help.
Comment: @acidgate so have any of these answers helped you?
Answer: You should definitely go for the "event" option. You could try the event with the following properties:
Event-Log: System
Source: Power-Troubleshooter
Event-Code: 1

This one is issued every time the system wakes up from sleeping mode (suspend-to-ram). Not sure if it will work for hibernate.
Also if this event is not good for any reason, you could try  finding other events. Just send your system into sleep mode, wake it up, and then look for anything related to power in the "System" event log.
Comment: Also, I can confirm that the same trigger fires when waking the system up from hibernate. Thanks for the answer!
Comment: Where can we find a list of ALL these events, specifically ones like these that Task Scheduler can listen to? All the search terms I'm trying are too darn generic to find references online. TY!
Comment: @Chazbot I  don'n think such list exists. Also, no software listens to these events, they are just logs. They are emitted by various software and just saved by Event Logger.
Answer: On my AMD system the "Power-Troubleshooter" event did not work. What worked was:
Event-Log: System
Source: Kernel-Power
Event-Code: 107
Answer: Sleep then wake up your system.
Open Event viewer then click Windows Log > System
Look at top information's souce and id.
Enter this event log ,source and event code information as trigger
In intel my conf:
Event-Log: System
Source: Kernel-Power
Event-Code: 507

Answer: If you don't object to using a third party (paid) program, it appears Macro Express™ will do as you require. There's a support post for restarting Dropbox when the machine awakes. The advice is specific to the program, but to avoid broken links:

How it works - System Event activation Windows sends messages when
certain events occur. When Windows wakes up from sleep, a
WM_POWERBROADCAST message is sent with the message's wParam set to
PBT_APMRESUMEAUTOMATIC. By creating a macro with a System Event
activation with these values a macro will run when Windows wakes up.
Macros can be set to run when other system events occur. All that is
needed is to find the correct message values for the event. Reference
pages document the values for system messages. Message values may be
shown in decimal (536) or hexadecimal (0x218) formats, but the system
Event macro activation expects decimal values.
The WM_POWERBROADCAST value is 536 decimal and the
PBT_APMRESUMEAUTOMATIC value for wParam is 18 decimal. These values
are used in this macro to run when Windows wakes up.

The support document is a focus on Dropbox, but my experience with Macro Express™ suggests that changing one line of the code (program name/location) will be an easy edit. The document also includes a download of the .MEX file, the native format of a saved macro.

How to schedule a Windows task on wake?


turn off alerts on an announcement list

Question: How can I disable email alerts for an announcement list (that is, prevent users from signing up for alerts on this list)? I looked at the list settings in the UI, but did not see a way to do this. I also searched online for a PowerShell approach, but only found a way to disable email alerts for an entire web application.
Answer: If you are ready to override permissions for that list, you may create custom permission level(s) and remove "Create Alerts" permission from that permission level(s).
Answer: I don't think it is possible to disable alerts just for a single list in a user-friendly manner.  There are some rough workarounds you could do though, depending on how badly you need these blocked ...

Write a Timer job to delete any alerts created for the blocked list.  This is very ugly from a user experience as it lets people think they successfully created alerts but it accomplishes what you are looking to do.
Use a URL Rewriter tool to intercept the Subscribe To Alert page for that specific list and redirect the users to a friendlier "Not allowed" page.  This is better but still not ideal.  It also requires more manual work as the rewrites have to be managed by hand on each server in the farm

turn off alerts on an announcement list


Shortened complex sentences or simple sentences with multiple subjects/predicates

Question: In sentences akin to "I like to cook and eat" or "John and Jill should come over tomorrow", we have multiple sentence members of the same type which are joined by conjunctions. My question is are these just short versions of complex sentences "I like to cook and I like to eat" and "John should come over tomorrow and Jill should come over tomorrow" respectively or are these conversely, just simple sentences with two predicates and two subjects?
Answer: These are simple sentences with a single, compound subject (or other element)
So "John and Jill" is the subject in the first sentence.  That is one subject (not two) but it is compound.
"Cook and eat" is another compound, and similar arguments apply.  It is a compound of two infinitive verbs, subordinated by "to" to the main clause headed by the verb "like".
These may have the same meaning as two sentences. They may be considered a paraphrase of the longer pair of sentences. But they are not formed by ellipsis or shortening of a structure.


Isomorphism of graphs or equivalance of graphs?

Question: By definition of graph isomorphism, it is apparent that two isomorphic graphs must have the same number of vertices, the same number of edges and the same degree of vertices. Is the following two graphs
 isomorphic?. These two are bipartite graphs, but i am not sure whether i should call them isomorphic. Or, can i say that these two graphs are equivalent, i.e., fig.I=fig.II ?
Answer: These graphs are isomorphic; the bijection that exhibits the isomorphism is a reflection in the central horizontal axis.
If there is such a concept of equivalence of graphs distinct from isomorphism of graphs, I've never heard of it; Google also doesn't seem to know about it.
Answer: you have a simple graph, by definition:
An isomorphism a simple graph G to is a simple graph H is a bijection $f: V(G) \rightarrow V(H)$ such that $ uv \in E(G)$ if and only if $f(u)f(v) \in E(H) $ then we say "G is isomorphic to H", written $ G \cong H$ Here you could give a direct bijection
$$ 1\rightarrow 5 $$
$$ 2\rightarrow 6 $$
$$ 3\rightarrow 3 $$
$$ 4\rightarrow 4 $$
$$ 5\rightarrow 1 $$
$$ 6\rightarrow 2 $$
This function is injective and surjective.
One other way you could start to analyse adjacency matrices. You will see that the applying row and columns permutation on A(G), you will get A(H), this also is a proof of the isomorphism.


Can't change wallpaper for Secondary Desktop; I've already tried system preferences

Question: I can't change the secondary desktop wallpaper. I've already gone to system preferences and have chosen a wallpaper for second desktop, but it remains all white???
Answer: On Mountain Lion, you have to open System preferences and drag the window to corresponding desktop at which you want to change the wallpaper. Then select background picture of choice.
Answer: I occasionally use two monitors, and I use a program called SwitchResX (in the menu bar) to easily switch between resolutions, color spaces and monitor sets so I don't have to go to the clumsy system preference pane to click all over the place.
I have some scripts which automatically change desktop wallpapers. What I've noticed is that, you should basically have the monitor in question at least temporarily set as the main display when you want to change the wallpaper. When you're done choosing a wallpaper for it, you can set the other one as the main one again. Now the secondary monitor should keep the wallpaper that you've set. I believe this is a setting thing, but in my case I keep separate wallpapers on each monitor, and the time-specific scripts only affect my main monitor while the secondary one's wallpaper has to be changed manually, using the procedure that I just described.
I think you should be able to control wallpapers of multiple monitors using Mac's own system preferences, but since I found it so clumsy and don't do it that way, I can't assist more than what someone already said about it in the previous comment.


Showing that an orthonormal set becomes a basis for the Hilbert space

Question:
This is an exercise from Folland Real Analysis Chapter 8 that I am stuck at. I am actually stuck at (b). I succeeded in showing that $H_a$ is a Hilbert space and the given set is an orthonormal set of $H_a$. However, I cannot show that the given set becomes a basis. I tried to apply the Stone Weierstrass Theorem; but the collection of finite linear combinations of the elements of the given set does not seem to form an algebra. The multiplication of $\sqrt(2a)sinc(2ax-k)$ and $\sqrt(2a)sinc(2ax-k')$ for arbitrary integers $k$ and $k'$ does not seem to be expressible as a finite linear combination of the given set.... I cannot find a way through. Could anyone please help me?
Answer: Based on part (a), I think they want you to use the fact that $\hat{f} = \chi_{[-a,a]} \hat{f}$ and Plancherel's theorem (i.e. the density of Fourier coefficients).


Do GPL-licensed engines permit modifying and closing the source code?

Question: Is it legal to modify and redistribute a GPL engine, under a more restrictive license (for example closing the source code)?
Answer: GPL-licensed software cannot become closed software. If you 'fork' it, then the rights on this fork remain the same (see GNU General Public License on Wikipedia).
Comment: There is NO exception and there is no exception needed. Once GPL, always GPL.
Comment: It is all the same. When GPL was created I do not think that they thought about chess :-) The license is only about changing and including the software. If you 'call' for example stockfish from another application then you install stockfish executable next to the application.
Comment: Why downvote? It's correct.
Comment: So, there is so exception for chess engines right? It is the same?
Comment: No exception* sorry for typo
Comment: Why do you think that they should have thought about chess? What's the exception?
Comment: That was what I wanted to hear :)
Answer: Short answer: No. But for chess, the answer: Yes. Read on.
GPL is quite complicated. Essentially, it requires the application be open-source.
From: http://www.gnu.org/licenses/gpl-faq.html
Can I sell a GPL project?

You are allowed to sell copies of the modified program commercially, but only under the terms of the GNU GPL. Thus, for instance, you must
  make the source code available to the users of the program as
  described in the GPL, and they must be allowed to redistribute and
  modify it as described in the GPL.

Thus, it's ok to sell the Stockfish chess engine which is licensed as GPL.
Why open my source?

A crucial aspect of free software is that users are free to cooperate. It is absolutely essential to permit users who wish to help
  each other to share their bug fixes and improvements with other
  users.

In theory, whoever gets the source code could improve the engine and therefore benefit the whole community. However, in practice this has never worked well.
Can I change the license to something more restrictive?

No. The GPL says that your modified versions must carry all the
  freedoms stated in the GPL. Thus, anyone who receives a copy of your
  version from you has the right to redistribute copies (modified or
  not) of that version. You may not distribute any version of the work
  on a more restrictive basis.

But... ICC Chess Club bundles their software with the Stockfish engine and I don't have their source code. Is that illegal? No.
CHESS IS DIFFERENT
Chess engine almost always runs as a separate process from the application itself, connected to the application through pipes. This is very different to traditional programming where you bundles the GPL source code within the application.
Technically, there is no need to link (statically or dynamically) the GPL engine while compiling the GUI application. The engine itself is an executable that can run independently. Everything in the FAQ is only valid if the application links with the engine, if that isn't the case, there is no such thing as GPL license restriction.
Try to download Stockfish, do you see something like Stockfish_64bits.exe? This is a working executable that is independent to whatever chess GUI you'd like to use. You can even run it directly in the terminal. The engine is not linked to any chess GUI, thus it's always legal to bundle it with a commercial non-GPL chess GUI.
You can read more here
What does that mean?
It's perfectly legal to bundle a chess engine with a closed-source application if the engine is an independent executable. The GPL license simply don't apply here. But if you compile the engine with the application, you must provide the source code for your entire application. For example, ICC Chess Club is allowed to distribute the Stockfish engine without providing you their source code.
Comment: Do not think that there is an exception clause for chess in GPL :-)
Comment: `Chess is different` sounds like exception. The case that you describe goes for other types of software too. BTW. The question was about modifying and changing the license, your reply not.
Comment: @Marco did you even read it? Nobody said about exception.
Comment: Nice effort but it's actually answer of another question. I'm asking about chess engines, not chess apps that run engines inside.
Comment: @Saibot I answered like that because you were asking about chess application in another post and then notified me about your question. Please note chess engine by itself is totally useless and meaningless in all circumstance. If u insist on only and only engine then the answer is NO.
Comment: Sorry but I never asked for chess apps, also the question is very clear in this topic. For some reason you want to believe that I ask about apps. I also totally disagree that "chess engine by itself is totally useless and meaningless in all circumstance" How do you think chess engines are developed, by aliens? Chess engines are usually based on another engines, for example Rybka is based on Fruit, Komodo is based on Doch, Stockfish is based on Glaurung.


What is correct, "in the British Islands" or "on the British Islands"?

Question: What is correct, "in the British Islands" or "on the British Islands"? Is there a general rule?
Answer: Context, context, context!  It depends on what sort of sentence you're writing; we might say "There are many countries in the British Islands" but also "On one of the British Islands there is a mountain called Pillar." We cannot possibly give a general, all-encompassing rule for this, though given a sentence we could instruct on which is correct. To decide which applies in a given context, you might consider whether the object in your sentence would most likely be described as on or in something else; a mountain rests on top of land, while a country is one of many in the group of Islands. But this is perhaps a difficult determination to make for a non-native speaker. If given a sentence as an example of your confusion, perhaps more instructive assistance could be provided.
Answer: When speaking of territory, the general rule is to use the preposition "in" rather than "on". As the "British Islands" is a term that refers to a group of states, "in" would be used instead, i.e. "in the British Islands".
Comment: Any particular reason for the downvote?
Answer: As Stephan mentioned, you should use the word in, rather than on. Another point is that people don't normally say "British Islands", the normal term is British Isles.
The British Isles is a geographic term covering the UK, Republic of Ireland and the Isle of Man which is a British overseas territory.


I am an Indian and currently holding a 1 year Dutch Living Permit. Can I enter the UK?

Question: I am an Indian citizen currently living in the Netherlands. I have a 1 year Dutch residence permit, can I enter the UK without a separate visa?
Comment: What @HankyPanky said.
Answer: No, you cannot. From Timatic:

Visa required.
Visa Exemptions:

Nationals of India arriving from Ireland (Rep.) with a valid biometric C visa endorsed "BC BIVS" issued by Ireland (Rep.). The
  passport must include a valid Irish entry stamp. Passengers are
  permitted to stay in the United Kingdom until the expiry date of the
  Irish entry stamp.
Passengers with a "Permanent Residence Card of a Family Member of a Union Citizen" or a "Residence Card of a Family Member of a Union
  Citizen" issued by Netherlands to family members of a national of
  Switzerland or an EEA Member State . They must travel with or travel
  to join the national of Switzerland or EEA Member State. This does
  not apply to passengers with a different type of residence permit.
Passengers with an EEA Family Permit issued by the United Kingdom if the holder is traveling with, or to join the EEA or Swiss national.


To connect or to disconnect mathematics and platonism?

Question: How [do philosophers] strongly support or refute the view that: mathematics is a bag of tricks for real-world problem solving; undecidable statements are an irrelevant and harmless side-effect of an obvious consistency of axioms (capable of producing essentially only trivial results, however deep & wonderful they may appear); and mathematical platonism of eternal truths a psychological fallacy?
Comment: These sorts of generic questions are best addressed by reading encyclopedias, e.g. Wikipedia has a long menu of mathematical philosophies that you can choose from.  [Embodied mind theories](https://en.wikipedia.org/wiki/Philosophy_of_mathematics#Embodied_mind_theories) and [empiricism](https://en.wikipedia.org/wiki/Philosophy_of_mathematics#Psychologism) are probably the closest in spirit. However, consistency of axioms (even of arithmetic) is far from obvious, and most undecidable statements are not related to consistency (e.g. the continuum hypothesis), so you won't get everything.
Answer: This is not a single logically coherent view, its a collection of views that have little to do with one another, other than being condescending toward mathematics as it is practiced.  Some of them are contentious, some have followings and others appear to matter to a few individuals, some seem obvious to me, some are clear to no one.  None of them are related.
The purpose of mathematics may in fact be to solve real-world problems, but that does not explain very much of how it came into being.  Whole disciplines have been dominated by problems and practices with little or no practical value, like doing geometry with an irrationally restrictive set of tools, factoring all fifth-degree polynomials algorithmically, or determining whether there is a pattern to the structure of the transfinite sequence of ordinals.  In fact, it is surprising to a certain swath of philosophers and philosophically inclined scientists (e.g. Eugene Winger) that the kind of math that arises naturally from such bizarre investigations is, in fact, useful.  Some of them  (e.g. Tegmark) find it so unlikely that they overreact and imagine that math must be what the world is made out of.
The 'obvious' consistency of mathematics has been in question since Frege failed to conquer Russel's paradox.  Ways to stay clear of the inconsistent parts have been proposed by modern formalism, intuitionism and other schools philosophically, by interesting logical tricks like fictionalism in the middle ground, and by internal mathematical models like Woodin's attempt to describe the network of all possible models of set theory in a single metamathematical structure.  Whether all this is pointless or not, people are going to do it.  Potential inconsistency, even when just hinted at, is a human obsession.  So why go out of your way to declare it pointless?
Whether mathematics has real logical content is a good question, but not related to its purpose, or to its consistency.  Wittgenstein, notably, thought all of mathematics was in fact made up of tautologies.  This is sometimes called mathematical trivialism.  I agree with the reasoning.  But very few people pay attention to it because it has nothing relevant to say.  Tautologies can easily be so complicated that any given individual is quite unlikely to come up with them, and most of mathematics is at least that complex.  So whether this is content or not, it historically enables science, and entertains mathematicians.
How to address the fact of the obvious impossiblity, but apparent necessity of Platonism is another issue altogether, and again, independent of all three of the prior ones.  Most mathematicians still have to work in a way that presumes Platonism.  But then they carefully formalize any results, because we know certain corners of logic fail.  But we have no better reason to trust the formalism than the original framing -- they are both just stuff we made up.  As an alternative, neo-Intuitionists have proposed the idea that mathematics is really a branch of psychology, investigating which of our most basic natural intuitions do and do not fit together passably well, including the specific delusion of Platonism, why we are led there, and what the alternatives would be.  I hold this position.  It makes sense that if we can work out a good basis for constructive mathematics, it will provide a single understanding that replaces two incomplete approaches.  But overall, very few people care.
(There are a lot of random references in there, and I am not making them links, the SEP is searchable, so is this exchange, and Google works.)
Comment: Thank you for your reply, esp. for neo-intuitionism. I tried to unite  the 3 views, so I added the one on undecidable statements as an example of a deep result, to anticipate an easy refutation of the first position. The third quite unwillingly & aiming at strengthening my adherence to mathematical platonism through overcoming opposition. I know there are learned & lengthy treatises on these subjects. I believe mathematics is peculiarly located between abstract and concrete worlds, and that natural numbers are a stronghold preventing its subjugation to emotional needs & intellectual curiosity.
Answer: The best way to do that would be to do what philosophers of the mind do, and reject historical forms of realism like objective reality, and Cartesian duality. Gilbert Ryle in his The Concept of Mind attacks Cartesian rationalism, and purports to show that the mind-body duality is a category mistake. In philosophy, the position that defends that psychology is source of knowledge is called psychologism. Robert Audi in his Epistemology, in fact, accepts that there are five sources of knowledge: perception, memory, consciousness, reason, and testimony. A single class in Psychology 101 would manifest the obviousness that these are the objects of empirical study.
The position in the analytical philosophical tradition is that scientific statements about language (pscholinguistics) and mind (cognitive science) should be admitted into philosophical discourse, and thus elevate the importance of empiricism in philosophical debate.
There is a long standing epistemic debate among various flavors of rationalism and empiricism regarding the certainty of knowledge, and this philosophical clash is highlighted with the Agrippan trilemma which strikes at the heart of three types of rational argumentation, the axiomatic or foundational, the circular, or those of infinite regress. Ultimately, psycholinguists and philosophers who align themselves with empiricism (Gilbert Ryle, Jaegwon Kim, Ray Jackendoff, Steven Pinker, Daniel Dennett, George Lakoff, and Mark Johnson, eg.) have leveled a series of philosophical attacks on objective realism in one way or another of various strengths. Dennett for instance is a physicalist who argues there is only the physical and that consciousness is an illusion. George Lakoff and Mark Johnson advocate a philosophy they call embodied realism which rejects objective realism entirely. If you want a detailed roadmap because you accept cognitive science as a path to truth, consider reading Philosophy in the Flesh by Johnson and Lakoff who articulate an ontology that accepts both supervenience and rejects Cartesian duality.
Comment: Thank you, this is a whole lot to explore. But I don'y understand whether you support or refute the view expressed in the question. Also, why not keep the "would you" of the original question? Are personal opinions not allowed here?
Comment: I'm still getting my sea legs. Opinion-based questions are mostly a no-no from what I can glean. https://philosophy.stackexchange.com/tour has a specific proscription on them. See the section that says "Get answers to practical, detailed questions".
Comment: @exp8j There are already three close votes leveled against your posting, and it might be that your ask rubs someone the wrong way. I've noticed some people vote against posts that contradict their metaphysical presuppositions about philosophy.


Are Skylanders "Adventure Packs" compatible with Skylanders Giants?

Question: I have some level packs from the first Skylanders: Spyro's Adventures I was wondering I they were usable in Skylanders Giants and if so in what way. Do they unlock different levels in the new game or just the old ones? Do they still work as a powerup item if placed mid level?
Comment: I thought that they didn't work so I looked it up and it was true. I ordered an adventure pack and sure enough, it worked. Now I can play with both series.
Answer: They function more or less the same as in the first Skylanders game.  The level you unlock is the same, and has the same storyline, but the gameplay might be a little different since they took the same level layout but used enemies from Sky: Giants instead of just using the enemies from Sky1.  You can use it as a powerup item mid-level, although it might ask you if you want to play the Adventure level.
Answer: Yes, literally everything from Skylanders Spyro's adventure can be used in Giants, and the re-makes but re-make lightcores from giants can't be used in spyro's adventure.


Macbook pro default apps installed under different apple id?

Question: I just got a 13 inch MacBook pro, and it came with a lot of default apps installed (e.g. Garageband, iMovie, numbers, keynote, pages, etc.). There were also updates available on the app store, but when I clicked the update button I got the message: "... cannot be updated because it was refunded or purchased with a different Apple ID." So what Apple ID downloaded this app other than my own? Is there a way to fix this other than deleting and reinstalling everything?
Comment: How did you "just get" a MacBook Pro? From a family member or friend? Did you buy it off Craigslist/eBay/whatever?. It is likely that the apps are owned by the previous owner and you can't change the owner (annoying as that is) So deleting the apps (and support files) are likely your only hope. If it was me with a new (to me) Mac. I would wipe it and reinstall *everything* macOS, Apps, etc. from scratch.
Comment: @SteveChambers The MacBook Pro was from a family member, I'm pretty sure it was from Costco. I reset my laptop and it seemed to work, thanks for the help!
Answer: Sure, delete the app in question from the Mac and empty trash.
Then open the App Store from the account (fast user switching type of account) you want to manage updates on that Mac. Sign in to the App Store if needed with the AppleID You prefer for your updates.
Get those apps tied to the correct AppleID.


In "The Hero of Ages" how did Spook know to write in metal when sending his messenger?

Question: In the book "The Hero of Ages" Spook removes his spike and sends a messenger off to Vin. How did he know at that point to make sure the message was written in medal rather than just a piece of paper?
Comment: How he knew to do this is revealed explicitly at the end of "Mistborn: Secret History".
Comment: I'm pretty sure Spook was doing this long before that scene happened. He didn't know about the significance of the spikes, but he was sending metal-inscribed messages from almost the beginning of _Hero of Ages_
Answer: All of the Final Empire's agents under Elend were using memorized messages or metal-inscribed ones.
Ruin tipped his hand to get free during the events of Well of Ascension.  Ever since Sazed discovered his journals explicitly altered, and compared them to Kwaan's original metal inscription at the Inquisitor home (which specifically called out that Ruin was changing the words everywhere it could), all the good guys knew that written words could not be trusted to stay the same.  Within the first few chapters as Elend is moving the army around, it's mentioned that all his scouts and messengers are following the same procedure as Spook.
Actually, here's a quote from their planning meeting in Hero of Ages Chapter 12 where Spook is doing that already:

Demoux stood. "We had a steel-inscribed message from Spook while Your Majesty was away," he said. "The lad says that the faction controlling Urteau is made up of skaa rebels."

And here's another thought from Vin from Chapter 21 where it's made explicit.

But, could she even trust the logbook's words? The force she had released, the thing she called Ruin, had proven that it could change things in the world. Small things, yet important ones. Like the text of a book, which was why Elend's officers were now instructed to send all messages via memorized words or letters etched into metal.
Answer: Because Kelsier explicitly told him to use metal.

Kelsier nodded. "Listen to me. You're going to wake soon. I need you to remember this part, even if you forget everything else about the dream. When the end comes, get people underground. Send a message to Vin. Scratch the message in metal, for anything not set in metal cannot be trusted.
Mistborn: Secret History - Part 6: Hero - Chapter 6

(emphasis mine)
The reason Kelsier told him to do this when it was already common practice was because the other common option was memorization and he needed to make sure that the message was something Ruin could get to, but not easily.


How to add a keyboard-layout applet switcher to Fluxbox toolbar?

Question: In Manjaro Fluxbox there is no keyboard layout switch in the panel/toolbar tray.
How do I add that?
Answer: I tried ibus, but had 2 problems with that:
 - could not set the keyboard variant (at least in its GUI)
 - did not support switching keyboard layouts with just Alt + Shift (it wants also a "real key" in addition to that)
Based on https://bbs.archlinux.org/viewtopic.php?id=212804 I had success with gxkb (I did not try the other *xkb mentioned as the OP was happy with gxkb).
Some reading of gxkb man page revealed that while it is running you can use setxkbmap to configure it. It works fine on Openbox + Tint2 panel.
In my openbox autostart file I added:
gxkb &
# just to make sure
sleep 1
setxkbmap us,hu ,102_qwerty_dot_dead -option grp:alt_shift_toggle

Answer: The question is about the toolbar.
The below solution is a workaround for Wbar, a launcher which cannot use any keyboard applets.
This worked for me in Manjaro Fluxbar 15.09, which had Wbar installed by default.
Manjaro Fluxbox 15.10 uses Plank instead, and Wbar doesn't seem to run anymore. To use Plank, see this solution. (On the other hand, Plank doesn't seem to work correctly in 15.09.)

Pending a definitive answer, as a workaround for Manjaro Fluxbox one may consider the Wbar dock as an alternative way to access each layout as a launcher.
This is a light dock with fewer options than even the lightest out there like Plank and Docky. It is installed by default in Manjaro-Fluxbox 15.09.
It is meant as a simple application launcher (although it can also show open windows icons as a taskbar if needed).
It can be edited to launch whatever command and then assign a name and an icon to be shown in the Wbar.

The commands to be used for each keyboard layout are discussed here.
The general form is (e.g. French):
setxkbmap fr

For icons, search the internet for "flag icons" or "letter icons"; alternatively, customized icons can be created. For example, below I have used a png file easily created by screenshot-cropping a grey wallpaper; on the grey image, the letters were written with Shutter).

Or, with void icons by just adding letters in Shutter:

They are enlarged when focused with the mouse:

In the images above, I removed the 'iconbar' and replaced it with the Wbar as indicated here.

Maybe even more convenient is to switch keyboard layouts through a launcher like Synapse by creating layout-specific desktop-file launchers.

More on that, here.
Synapse is not depending on any panel, toolbar or dock, but in a similar way keyboard layout selection will work in any panel launcher like Unity Dash, Xfce WhiskerMenu, KDE launchers (Kickoff, Homerun, Lancelot etc), etc.
Answer: Install ibus in the software manager:

Start with command ibus-daemon.
It should already appear in the systemtray.

Right-click the tray icon to access preferences, set a switch shortcut key and add layouts.
Add this line to ~/.fluxbox/keys:
ibus-daemon &

Switch the layouts by left clicking the tray icon or by using the shortcut to see list of choices.

This solution seems to have a serious limitation in that it may lack access to some layout variants.


Why are antibonding molecular orbitals formed?

Question: When two atomic orbitals make one molecular orbital there must be an antibonding orbital also. Why should they make also an antibonding molecular orbital, such as the $2\mathrm b_2$ orbital in the scheme below?
Comment: also maybe there should be an anti-bonding orbital because suppose if there are a total of four electrons in the two orbitals of two atoms, it can only be distributed between BMO and AMO because one MO can only hold two electrons.
Answer:
Why should they make also an antibonding molecular orbital?

Orbital symmetry must be conserved. Thus, when you mix orbitals, the number of orbitals must also be conserved. As a consequence, when two orbitals are operated on to produce new orbitals, two new orbitals must be created.
Think about it conceptually this way: When two orbitals that have the same symmetry and appropriately matched energy come together, a bonding orbital is formed. This bonding orbital contains all of the "good orbital stuff" from that pair of orbitals. But, because there were two orbitals originally, there has to be "orbital stuff" left over. This leftover "orbital stuff" forms the antibonding orbital.
Now, the screwy part is that orbitals are not real. They are mathematical constructs to describe the wave-like probabilistic properties of electrons. If there are no electrons in the orbital, then the orbital is not really "there". So, while an antibonding orbital is formed, it is not real unless it has electrons in it. In the case of water above, the antibonding orbitals are not populated, so they don't exist.
Comment: @CHM: I think it's better to leave it there -- the fact that orbitals aren't "floating balloons waiting to be filled" can get rid of quite a few misconceptions. It's fine if an answer deviates a bit :)
Comment: Good answer, except I'd remove your last paragraph entirely. It's not necessary for the OP's understanding, as it really is a philosophical question. What do you think?
Comment: What I mean is that the "reality" of orbitals has nothing to do with the depiction most high schoolers have of them. To me, they're just as "real" as anything else. I also happen not to agree that they spontaneously come into existence when the atom needs them. It's fine to point out that they're a solution to a mathematical equation, but I [wouldn't go beyond that](http://lanl.arxiv.org/abs/1111.3328) as the matter [is a point of debate](http://arxiv.org/abs/1101.4575).
Comment: If antibonding orbitals do not exist, what do electrons get excited into when the molecule absorbs uv light?
Comment: @OscarLanzi a higher lying, multi electron excited state. At the end of the day, we know from Quantum mechanics that a multielectron state is not going to be describable exactly by a product, or linear combination of products, of one electron states unless you have an infinite number of them. But in that case, the choice of orbitals is basically arbitrary, so we can't say that one set of orbitals is more real than another.
Comment: @OscarLanzi maybe *are not real* because they represent a probabilities...and we can't say probalities exist, I suppose...


Thermographic camera vs infrared camera

Question: AFAIK, all objects above 0K emit infrared radiation. It is an electromagnetic radiation, like visible light. I guess thermographic and infrared cameras work on the same principles, but their images are very different, the former is false color and very different from the visible image, the latter is black and white and usually correlates to the actual visible image, at least that's what I've seen so far. So physically, how exactly are they different?
Comment: False-color is a post-processing step which can be applied to any collected image regardless of the wavelength range the sensor operates in.  "thermographic" is a fancy title for any camera which is sensitive to the temperature ranges the user is interested in. <-- which could vary quite a lot.
Answer: At or around room temperature objects emit light in the far infrared. Cameras that detect this radiation generally give the false colour images that you describe. Because the camera sees radiation emitted by the objects no external source of light is required.
However a second type of camera operates in the near infrared and requires an external infrared light source to illuminate the field of view. These cameras give the black and white images you describe.
The near IR cameras have much higher image quality because the wavelength of the light is shorter and the intensity of the light is much higher. However it does mean carrying around a near IR light source to illuminate whatever it is you're trying to photograph. Wildlife documentaries tend to use near IR cameras because they give a good image of the wildlife but without scaring the animals by illuminating them with visible light.
Comment: Yes, near IR is very similar to visible light and behaves pretty much like the visible light. The Sun deas emit near IR, so streets are flooded with near IR in sunlight. The thermal emission is not monochromatic - see the blackbody radiation. Human body is not a blackbody (rather a grey body), so the spectrum is a little different, but still not monochromatic. Heating an object rises the frequency of the maximum of the emitted spectrum. Hot iron can glow in visible light (even though maximum can be in IR).
Comment: All true but given the vagueness of the OP's question, hard to say if this is what he's after.
Comment: Near IR means closer to visible light, right? So it means it works very similar to visible light, with reflections and all? I guess the sun also emits near IR light, that's why consumer "normal" cameras all have IR filters. So an object can *reflect* near-IR, in any number of different wavelengths, but an object only *emits* far IR, in a single wavelength, based on its temperature? If I heat an object, will it's radiation come closer to visible light?
Comment: On a related note: An interesting trick to test if your TV remote is working is to look at the LED on the front through a digital camera (such as a phone's camera) while pressing a few buttons. You should see a bluish/purple light.

Thermographic camera vs infrared camera


How do I install Half-Life 1 and 2?

Question: How do I install Half-Life 1 and 2 on Ubuntu 12.04 if I already have the game on a Windows installer CD and on Steam. I tried it with Steam, but the game didn't launch. I also tried it on wine with the Windows installer, but it didn't work either.
Comment: They're both supported by playonlinunx http://www.playonlinux.com/repository/?cat=1&type=0
Answer: If you came here to play HL, HL2 or any other Steam for Linux released game see How can I install Steam? for the answer which is a lot simpler than this. This one only apply to games outside the Steam environment or not yet on steam. Also know that Half-Life is natively supported in Ubuntu. Most likely HL2 will follow.
To play both, HL and HL2 (Not through steam) you first need the Wine PPA (It is much better than the actual version that comes with Ubuntu). So first install the Wine PPA (Does not matter if you already have PlayOnLinux installed). PlayOnLinux can work without the need of having Wine installed since it will eventually download its own version of Wine if it detects you do not have one (Including addons which are similar in use as winetricks). It also downloads specific Wine versions even if you have Wine install for some specific cases (Some games in PoL depend on specific Wine versions).
If you use Wine PPA or PlaOnLinux the game should work with no problem.

Follow this guide to install the latest Wine: http://www.winehq.org/download/ubuntu
After that go to Software Center and look for Wine with version 1.5.x. Right now it is 1.5.23. Install it. You can also install it via the terminal with sudo apt-get install wine.
Download PlayOnLinux from their website and install it.
Execute PlayOnLinux at least once so it can download the needed Fonts and configures itself for use.
If you try to run the games with Wine, first try to download, any needed libraries and additional packages the game needs. This can be done with winetricks. You can run winetricks from the Dash or from the terminal like winetricks --gui. For HL, HL2 and many other games I have tested, including but not limited to: Trine, Trine2, Portal, Portal2 and many others I recommend the following Winetricks installation:
Open Winetricks and select Select the default wineprefix

Select **Install a windows DLL or component

Install all that I have marked (and any additional you need for a specific app). This should cover many apps and games. I have not had any additional problems after installing this with many games:

The Physx component, even if you do not have Nvidia, you still need to install it for games that require it.
Now simply right click the installer for HL1 or HL2 and select Open with Wine. Tested again with both games. Working perfectly (Not the Steam version, only the older CD/DVD versions).
If you try to run the game through PlayOnLinux, the app will guide you step by step on how to install the game and will take care of many aspects of it's installation including needed DLL and other components to make it work right.
Comment: Can PlayOnLinux be installed without WINE?
Comment: @Anwar yes but PoL will eventually download its version of Wine if it detects you do not have one (Including addons which are similar to using winetricks). It also downloads specific Wine versions even if you have Wine install for some specific cases (Some games in PoL depend on specific Wine versions).
Comment: @Aditya actually, the answer provided in that link covers everything about steam (Even the additional components recommended by steam). I can only cover here how to install everything to use HL and HL2 without steam support.
Answer: Half-life 1 is now released for native Linux. It is available from Steam (http://steampowered.com)

How can I install Steam?
Answer: Check out this page for install instructions.
Currently there is no Steam or Source Engine for Linux, but recently there have been (more substantial than previous) rumors of a Steam Client for Linux, as well as a Source Engine port.
Answer: Install playonlinux. It is a wrapper around wine with some extra patches. It is free.

How do I install Half-Life 1 and 2?


Insert action in front of template, while maintaining entry slug

Question: We are attempting to implement a number of Pardot forms within Craft templates.  Since Pardot's form actions do not allow us to dynamically specify a return URL, our best choice is to use the form's URL as the return URL.
Our page is /about/contact.  We want one of three things to happen on this page:

If the user has an identifying cookie on their machine, display only a comment field, for example
If the user does not have a cookie saved, display the complete form
If the user is returning from Pardot, set a cookie and display a thank you message.

It's important to us that we maintain pretty URLs, so we have created a route in routes.php:
<code>return array(
  'about/contact' => array('action' => 'pardotForm/ManageForm'),
);
</code>
Our contact page is an entry in our Landing Page structure.  We've set that entry's slug to be something random so that Craft does not route to the default controller for that entry.  It is set to "contact-us-page".
We would like to maintain the actual slug on the contact page as "contact" so that we can use slug features in normal ways.
Is there any possible way to maintain our slug as "contact", our url as "about/contact", and still route to our 'pardotForm/ManageForm' action?
Answer: The easiest way to solve this, would be to use a template hook instead, and put all your PHP code in there.


Why is it said that the Tupolev Tu-144 had superior aerodynamics to the Concorde?

Question: A quote from this article:  "The Concorde had better range, braking and engine control but the Tupolev had vastly superior aerodynamics."
What is the basis, if any, for this statement on the aerodynamics of the two aircraft?
Comment: Frankly, that entire article should probably just be discarded. It appears to be written by someone who's briefly scanned the Wikipedia summary box and introduction for the articles of each aircraft...
Answer: Unfortunately, there is no hard data available (at least in open literature) to back up these claims.
One for the claim may be due to the fact that the Tu-144 was designed to fly higher than Concorde as its primary flight path was over land rather than water. Because of this, the L/D ratio of the Tu-144 was higher than that of Concorde (7 vs 8 in Tu-144D). Also, the Tu-144 was bigger and was meant to carry more passengers.

Photo Courtesy: globalsecurity.org
The Tupolev site offers an interesting explanation for this claim. Basically, they say that despite the engines and other subsystems being inefficient, the Tu-144 performed similar to the Concorde due to superior aerodynamics of the aircraft. The performance of the Tu-144's RD-36 engines was later brought up to that of Concorde's Olympus 593, at least in fuel consumption.
To quote,

It should be added that the engines were less perfect (by specific parameters the engines of TU-144 a/c were brought close to "Olympus" only in their last modification). All these negative initial data were compensated in the course of development of the project by high aerodynamic cleanness of TU-144 which was achieved by making the design more complicated and by lowering maintainability of the aircraft.

But without any hard data, it is not possible to compare the two aircraft directly.
Comment: Also [generic explanation in this answer](http://aviation.stackexchange.com/questions/17718/how-to-recognise-the-tupolev-tu-154-tu-204-and-tu-334/17721#17721).
Answer: Let's see if we can find numbers to support this claim:
Tu-144D:
Ogival delta wings without conical camber, cranked delta. A distinctly low set & a much simpler wing, a poor performer at low speed, hence the later addition of canards, with no doubt a big weight penalty.
Concorde production version:
Double delta (ogee/Ogival) shaped wings with conical camber, more curved. Advanced, highly refined wing design.
Comparing the characteristics:
\begin{array}{|l|c|c|c|}
\hline
  \text{} & \text{Tu-144D} & \text{Concorde} & \text{Comments} \\
\hline
   \text{Passenger capacity} & 155 & 120^{[3]} \\
\hline
   \text{Fuel load [kg]} & \text{95,000$^{[1]}$} & \text{95,680}^{[3]} \\
\hline
   \text{Range [km]} & 5330^{[2]} & 7222.8^{[3]} \\
\hline
   \text{Fuel/km [kg/km]} & 17.8 & 13.2 \\
\hline
   \text{Fuel/pass-km [kg/km]} & 0.118 & 0.110 \\
\hline
   \text{L/D (Low speed)} & ? & 3.94^{[3]} \\
\hline
   \text{L/D (Approach)} & ? & 4.35^{[3]} & \text{250 knots, 10,000 ft} \\
\hline
   \text{L/D (Mach 0.94)} & ? & 11.47^{[3]} \\
\hline
   \text{L/D (Mach 2.04)} & ? & 7.14^{[3]} \\
\hline
   \text{T/W} & 0.44^{[4]} & 0.373^{[3]} \\
\hline
\end{array}
$^{[1]}$ Plane and Pilot - TUPOLEV TU-144 - Source
$^{[2]}$ Tu-144 SST Technical specs - Source
$^{[3]}$ Wikipedia: Concorde - Source
$^{[4]}$ S. Maharajan: Design of Supersonic Transport - Source
So the specific fuel consumption is very close, with the Tu-144 at 7% higher. And I've used figures for the Tu-144D version which was a big improvement over earlier versions: those could not supercruise at Mach 2, unlike Concorde, which drastically reduced their range.
From Wikipedia:

It is unclear why Tu-144D's maximum achievable altitude would be lower than Concorde's even regular flight altitude, given that Tupolev's data claim better lift-to-drag ratio for the Tu-144 (over 8.0 for Tu-144D vs Concorde's 7.3–7.7 at Mach 2.x) and the thrust of the Tu-144D's RD-36-51 engines is higher than Concorde's Olympus 593 engine.
The lower landing speed compared to Tu-144 is due to Concorde's more refined design of the wing profile that provides higher lift at low speeds without degrading supersonic cruise performance – a feature often mentioned in Western publications on Concorde and acknowledged by Tupolev designers as well.

summary from Tony Buttler, 'Building Concorde':
Early on in the Concorde project, wind tunnel tests found that a wing of the right shape would generate overwing vortices at low speeds and high angles of attack. This meant a big increase in lift, which lowered takeoff and touchdown speeds.
Small strakes on the front fuselage were found to give superior results to canards (the canards interacted with the fin in undesirable ways). A fuel transfer system was used to trim the aircraft instead of relying on aerodynamic trim controls.
The Tu-144 relied on retractable canards for low speeds, while BAC had found a superior solution.
Conclusion:
My impression is that the basic aerodynamics of the Concorde were better. Tupolev tried to compensate by optimizing the surface smoothness at the cost of maintainability (to borrow from the other answer, "high aerodynamic cleanness of TU-144 which was achieved by making the design more complicated and by lowering maintainability of the aircraft"). This meant closing off access hatches, using large complicated skin panels to reduce the number of seams, etc.
Comment: I noticed I was looking down and up a lot when reading the characteristics, soI put the numbers in a side by side table. Please roll back if you think it's hurting the quality of the answer.


In which representation are monopoles of grand unifying theories classified?

Question: In the context of grand unification theories A.Zee's book states that $SU(5)$ (or $SO(10)$ if $SU(5)$ is considered as outdated as GUT candidate) as GUT and as spontaneously broken non-abelian gauge theory contains the monopole. I am wondering in which representation of $SU(5)$ it should be classified,  may be as a singlet? Or is this question not meaningful since the monopole is perhaps a soliton? So if it were a soliton, how would it be classified?
Answer: Monopoles are somewhat subtle, and there are different layers towards their classification, each being more correct than the previous one.
 Quick remark: what is usually called the $\text{SO}(10)$ model should more properly be called the $\text{Spin}(10)$ model, because it contains spinors. One has $\pi_1\text{Spin}(n)=0$ and $\text{Spin}(2n)^\vee=\text{PSO}(2n)$ and $\text{Spin}(2n+1)^\vee=\text{PSp}(2n)$. Also, one should point out that the correct GUT embedding reads $\text{SU}(3)\times \text{SU}(2)\times \text U(1)/\mathbb Z_6\hookrightarrow \text{SU}(5)$ and so, strictly speaking, the formulas below only make sense for $n=6$.

The ABC of magnetic monopoles.

Goddard-Nuyts-Olive: the monopoles of a gauge theory with gauge group $G$ are classified by the representations of the GNO/Langlands dual group $G^\vee$ (cf. Ref. 1). For example, the dual of $\text{SU}(N)$ is $\text{PSU}(N)$, whose representations are basically the adjoint and its tensor powers. Similarly, the dual of $\text{SO}(2n)$ is $\text{SO}(2n)$ itself, and that of $\text{SO}(2n+1)$ is $\text{Sp}(2n)$. The representations of these are all well-known.
Lubkin: the GNO monopoles are typically unstable unless there is some topological charge that protects them. This topological charge takes values in $\pi_1G$  (cf. Ref. 2), and so one may have non-trivial monopoles if and only if $G$ is not simply-connected. For $\text{SU}(N)$ one has $\pi_1=0$ and so there are no monopoles. On the other hand, $\pi_1 \text{SO}(n)=\mathbb Z_2$, so here one does expect a (unique) non-trivial monopole.
The SSB monopole: if the theory undergoes a Higgs mechanism $G\to H$ one has slightly more freedom in making stable monopoles (cf. Refs. 3,4). In particular, these are classified not by $\pi_1G$ or $\pi_1H$ but by $\pi_2(G/H)=\operatorname{ker}(\pi_1 H\to\pi_1 G)$. For example, if $G$ is simply-connected one has $\operatorname{ker}(\pi_1 H\to\pi_1 G)=\pi_1H$ and so the classification reduces to that of Lubkin. Indeed, if
$$
\text{SU}(5)\to \text{SU}(3)\times \text{SU}(2)\times \text U(1)/\mathbb Z_n,\qquad n\in\{1,2,3,6\}
$$
one has a
$$
\operatorname{ker}(\mathbb Z\times\mathbb Z_n\to 0)=\mathbb Z\times\mathbb Z_n
$$
classification. Similarly, for an $\text{SO}(10)$ model one has a
$$
\operatorname{ker}(\mathbb Z\times\mathbb Z_n\to \mathbb Z_2)=\mathbb Z\times\mathbb Z_{\lceil n/2\rceil}
$$
classification (this last equality is an educated guess; ask your friend the mathematician to be sure).

References.

Gauge theories and magnetic charge, P.Goddard, J.Nuyts, D.Olive.
Geometric definition of gauge invariance, Elihu Lubkin.
Magnetic monopoles in unified gauge theories, G.'t Hooft.
Particle Spectrum in the Quantum Field Theory, Alexander M. Polyakov.
Comment: WoW !! I had never thought, that it is so complicated. Thank you very much, that is much more than I expected. Just a little question : What does the index $1$ res. $2$ at the representation sign $\pi_{1/2}$, which representation is it ?
Comment: @FredericThomas $\pi_i G$ refers to the $i$th [homotopy group](https://en.wikipedia.org/wiki/Homotopy_group). In short, $\pi_0 G$ is the number of connected components of $G$; $\pi_1G$ counts the number of one-dimensional holes in $G$; and $\pi_2$ counts the number of two-dimensional holes in $G$.
Comment: Thank you very much!


Use an output device as a recording source under Vista/Win7 new sound API?

Question: As I understand it, Vista introduced a completely rearchitectured sound input/output system to the OS. In particular, before Vista there was a single system-wide sound mixer, to which output devices could be connected. For recording, it was possible to retrieve data directly from a recording device or from this mixer.
In Vista and later, as I understand it, there is no longer a system-wide mixer. It is possible, in theory, to route some sounds to one output device and other sounds to a different output device,1 and this requires separate mixers for each output device.
Now, I have a simple recording application that I would like to update to take advantage of this new API. In particular, I was hoping it would be possible to let the user select one of the output devices as an audio data source. My reasoning is that the OS probably mixes all the inputs into each sound device anyway, and hopefully provides a way to tap into the mixed data.
Is it possible to select an output device as an input into my recording application, and if so, how?
1Although I am yet to find any UI that actually lets one do this.
Answer: Loopback Recording


Fair use question relating to copyright law

Question: Good day. I currently work in the publishing field, but have a unique inquiry regarding fair use related to copyright law; I am interested in launching an executive summary service to assist busy clinicians who need quality summaries of the medical literature -- journal articles, etc. -- some under copyright law, some from open-access journals/Creative Commons, and some from pre-press repositories, etc. I would be charging subscriptions for my summary services, and I need a better understanding of whether I need explicit licenses from the publishers to be able to stay on the proper side of copyright law. I see a number of services in the marketplace which summarize business books or self-help books, but my research hasn't been able to uncover how they are able to proceed without triggering legal action on the part of publishers. Or are summaries of medical journal articles covered under Fair Use? Thanks!
Answer: Fair use is not particularly relevant to the enterprise of publishing executive summaries. Copyright protection extends to any and all creative works, so the materials that you create are protected, and you can sell them or give them away as you please. Copyright does not protect ideas and facts, it only protects the expression of those ideas and facts. There are practical about how to avoid accidental infringement – the simple answer is, don't copy, instead learn what the article says, then write your abstract anew, not copying the original expression. You may have problems with graphic objects, and may need to get a license to reproduce a (photo)graph, though many conceptual-simple graphs can easily be redone in some other graphing program, if you can guess what the underlying numbers are.


utility function always negative

Question: In a problem set, I found a strange utility function: $U(c)=-1/2(c^* - c)^2$, where $c^* =$ positive constant level of consumption. Does this function have economic sense?
Comment: Are you sure it's not $U(c)=-1/2(c* - c)^2$?  I ask because that looks an awful lot like a standard "bliss consumption" utility function used in macroeconomics problems. The factor of 1/2 is there so that the first derivative works out cleanly.
Comment: Yes, of course. You are right! Now I have understood the economics meaning of this function form, but I don't know how to interpret the possible value of c, such as the range of consumption levels that makes economic sense. I think there is just one level of consumption, namely c=c*, where utility equals 0. In fact, each increase in consumption level makes the consumer less satisfied.
Comment: OK, having confirmed this, I'll give you a proper answer below.
Answer: Remember that utility function only matters ordinally... that is, you only care if $u(A) > u(B)$, and $u(A) = 100$ with $u(B) = 10$ is the same thing as $u(A) = -1000$ and $u(B) = -1000.0001$ (both have $u(A) > u(B)$.)
Answer: As discussed in comments above, this should be $U(c)=-\frac{1}{2}(c^* - c)^2$. The economic intuition is that c* is the "bliss" consumption level.  It is probably your first glimpse at the idea of "satiation", which is an extension of the idea of diminishing marginal utility which allows discussion of situations where additional consumption actually produces disutility.  The most obvious example is the consumption of food, where c* would be the point at which you get "full".  But there are other contexts involving the study of externalities, where satiation is important, such as in environmental economics.
The utility function isn't that interesting by itself, but remember that utility maximization is done subject to a budget constraint so that in general c* will not always be attainable.  If you haven't yet, you will eventually see this utility function in the context of lifetime consumption and savings decisions, usually as a lead-in to Friedman's permanent income hypothesis.
Answer: To see if this function makes economic sense we must recall what the definition of economic rationality is:
A consumer is said to have rational preferences if:
1) preferences are complete (any 2 bundles can be compared)
2)preferences are transitive (in this case we know if $-\frac{1}{2}(c^1-c)>-\frac{1}{2}(c^2-c)$ and $-\frac{1}{2}(c^2-c)>-\frac{1}{2}(c^3-c)$
Then $-\frac{1}{2}(c^1-c)>-\frac{1}{2}(c^3-c)$
Thus our consumers preferences are rational and are consistent with economic theory.

utility function always negative


Why doesn't STP apply only to broadcast/unknown unicast frames?

Question: All known unicast/multicast frames shouldn't cause loops since they have a known destination.
So they can use all the available bandwidth.
What am I missing?
Comment: The actual destination in a broadcast is _every_ interface, and an unknown unicast destination is _unknown_, so it is sent to every interface..
Comment: Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can post and accept your own answer.
Answer: Source MACs are very often learned through broadcasts sent from that source. If you forward each broadcast through one of a choice of links, that link becomes the one associated with the source. If the link is non-optimal, so will the traffic towards that node by forwarded.
Imagine a ring of four switches. Which way should broadcasts be forwarded? How should the bridges learn the source MACs? You quickly end up with a bunch of flows across switches that shouldn't be in the path, causing unneccessary traffic in the network and needlessly congesting links.
What you'd need is that the distance of each MAC address is somehow passed from switch to switch. Since a TTL concept doesn't exist for Ethernet, that isn't possible.
Shortest Path Bridging is an alternative concept to STP where a spanning tree is created for each destination MAC, utilizing all redundant paths. Sadly, that hasn't really caught on yet in the industry.
Also, link aggregation (LAG) and multi-chassis link aggregation (MC-LAG) are techniques that try to utilize redundant links between switches. Standard LAG is limited to switch pairs and MLAG solutions are proprietary, so most networkers look for something else.
Most approaches prefer to use routed links and ECMP to distribute traffic - which can work quite well if done properly.
Comment: @RonMaupin I think sergeyrar was referring to *potential* bandwidth that is wasted on the blocked, idle links, and he was trying to utilize them.
Comment: I was thinking about alternative approaches to STP, since it wastes a lot of bandwidth.
For example: why not actually use TTL in Ethernet layer, and after an unknown unicast frame visited a switch install a drop entry for that VLAN-DMAC (for 30 seconds or so). But then comes the issue of application layer retransmissions that would just get dropped :D... oh well
Comment: @sergeyrar "Why not actually use TTL in Ethernet" - Ethernet doesn't have a TTL field and if you add that it isn't Ethernet any more. Basically, the Ethernet concept is to transport/forward frames across a network *unchanged*. A TTL field would break that. Initially, a shared wire or dumb repeaters/hubs where used that had no capability of changing the TTL. But you're getting the idea. ;-)
Comment: @sergeyrar, "_I was thinking about alternative approaches to STP, since it wastes a lot of bandwidth._" Actually, it can be a lot less than you think. Unknown unicast addresses are learned very quickly (it only takes one frame), and broadcast is nearly deprecated (ARP still uses it for IPv4, but IPv6 has no broadcast). There are many companies that will test software, and if it uses broadcast, they will not use the software. Multicast is the modern way to do such things. Cisco best practices also limit the broadcast domain.


"Undefined subroutine &HTML::Entities::decode_entities called"

Question: I'm getting the error

Undefined subroutine &HTML::Entities::decode_entities called`

using LWP::UserAgent, although the module is there, as well as the HTML::Parser module.
I suspect it has something to do with XS modules missing, since the function in question seems to be implemented in XS, but I am at a loss.
Comment: Can you show a short example script that demonstrates the problem?
Answer: Recent versions of HTML::Entities depend on getting the decode_entities routine by loading the HTML::Parser module's XS component.  Since the two modules are distributed together, this should not be a problem, but it's possible you have an older HTML::Parser version that didn't use XS instead (or multiple versions of HTML::Parser installed, with the wrong one being found first).
Check the $VERSION in HTML::Parser, look up that distribution on http://search.cpan.org/dist/HTML-Parser, and verify that distribution has the version of HTML::Entities that you have.
Answer: Are you missing this line:
use HTML::Entities;

From the HTML::Entities CPAN page, it should be used like this:
use HTML::Entities;
my $a = "Våre norske tegn bør &#230res";
decode_entities($a);
encode_entities($a, "\200-\377");

If you think there is something wrong with the HTML::Entities package, you can check the source on your system.  From bash:
vim $(perldoc -l HTML::Entities)

Once the file is opened in your text editor, you can check that the subroutine is defined.  I suspect that the package is correct though, it is more likely that the package isn't "used".
You can also test this at the command line to see if it works outside your program:
perl -MHTML::Entities -le 'print HTML::Entities::decode_entities( "Våre norske tegn bør &#230res" )'

Comment: I tried explicitly using the module as a test and it didn't work. It also doesn't work inside LWP::UserAgent.
Comment: Does the perl one-liner work?  Did you check the package to see if the subroutine was defined?  If all that checks out, is it possible to add your code to the post?
Comment: Can you post fuller code, please? I've used the current version of HTML::Entities recently, and it works fine. So I don't think it's the module.
Comment: @gpojd, if you bother to look at the current code, you will see that the subroutine is *not* defined in the Entities.pm file, intentionally: http://cpansearch.perl.org/src/GAAS/HTML-Parser-3.60/lib/HTML/Entities.pm : require HTML::Parser;  # for fast XS implemented decode_entities
Comment: @ysth, I could have sworn I had it defined on my version when I originally answered this.  I am not at that computer now, and can't check.  Either way, some of my instructions would have led him to "require HTML::Parser;# for fast XS implemented decode_entities" and probable answered his question.


How many volumes of the light novels did Durarara season 1 cover?

Question: How many volumes of the light novels did Durarara season 1 utilize? Where should I start reading if I want to continue from after the first season ended? (I know the second season is already being broadcasted). Also, are the light novels still on-going or are they finished?
Comment: The initial run of light novels (13 volumes) finished in early 2014, but a sequel series started up a few months ago (titled "Durarara!! SH"), and has two volumes out so far and is ongoing. Dunno where the first season of the anime ends, though.
Answer: Wikipedia and Manga Updates say that the anime covers the first three volumes of the light novels.
From Manga Updates:

Status in Country of Origin
13 Volumes (Complete)
Anime Start/End Chapter
Starts at volume 1
Ends at volume 3

(As per senshin's comment, a sequel light novel series titled Durarara!! SH is underway and has 2 volumes published at the time of writing)
Wikipedia excerpt about the anime adaptation:

An anime adaption of the light novels was announced in the wraparound sleeve of the sixth volume of the light novel. The anime is produced by Brain's Base and started airing on January 7, 2010 on MBS, TBS, and CBC. Crunchyroll simulcasted the anime at 480p and 720p within 24 hours of its Japanese premiere. Other users were able see the same episode in standard definition for free one week later. The anime adapted the first three novels, and it was licensed by Beez Entertainment for European release, while at Anime Expo 2010, Aniplex of America confirmed that they have the license to Durarara!!, later producing an English dub for a January 2011 release. The English dub was produced at Bang Zoom! Entertainment. The music for the first season was composed by Makoto Yoshimori, who also wrote the music for Baccano!.
Answer: Sorry, but I'd highly suggest you read the light novels translations if you can (even the ones that take place during the time of the anime). There a lot of stuff not even mentioned in the anime. A lot of the events are either cut out, shortened, or completely adverted into something similar, and all out to nearly bashing Izaya's character. It makes him out to a whole lot worse than what he really is. Preferably in Volume 9 for his case.
Comment: This is fine advice, but it does not actually answer OP's question.


Create Raster boundary polygon in Metashape itself using DEM or OrthoMosaic generated in Agisoft Metashape

Question: Is there any script/code/help available to create raster boundary polygon using OrthoMosaic created after DEM in Metashape. Sometimes it is required to calculate survey area covered/Processed
Comment: Metashape Professional has an area calculation under `Tools > Mesh`. Maybe photoscan has something similar.
Answer: Maybe...
This Python tool is part of a two part script process to produce a raster layer where the resulting raster values are the image overlap count for that portion of your reconstruction.
This first script (taken from the Agisoft website) produces an ESRI shapefile for each image footprint in the reconstruction.  This script needs to be executed in a Python window inside of Agisoft.
This second script executed in your favorite Python IDE will produce the raster layer from that resulting shapefile.  The second script requires an arcpy installation with a Spatial Analyst license. There is a script for arcpy 10.8 and arcpy 2.9.
Because Agisoft will reconstruct with only a few overlapping images, the resulting raster can be reclassified and used to remove poor quality pixels on the outer edge of the reconstruction based an overlap count of your choosing.
The Agisoft shapefile tool has been tested in both Agisoft Photoscan and Agisoft Metashape.  I am the author of the second script so send me any error messages you encounter and I will attempt to address the problem.


How to track logged in user daily in SharePoint online site?

Question: I need to store User detail in custom list including time log in SharePoint Online. I need to generate daily report for logged in user in SharePoint online Site.
Is it possible Programmatically?
Answer: You can use the audit log reports provided with SharePoint 2013 to view the data in the audit logs for a site collection. You can sort, filter, and analyze this data to determine who has done what with sites, lists, libraries, content types, list items, and library files in the site collection.
Check This: User Login Report in Sharepoint Online?
MSDN LINK Configure audit settings for a site collection
Comment: Is it possible Programmatically? I need to store it custom list.
Answer: Audit report is the best approach , you can export the audit log to a library or list if you need .
Or if you are a global admin , you can go to Admin center--Report--Usage , select SharePoint --user , under Details you can view the detail of user's actions .


How to install GMLAS driver, working for OGR command line tool?

Question: Normally I run my OGR SQL syntax within OSGeo4W shell. I want to try out the GMLAS driver, but can´t find a distribution where it´s installed. I´m on windows. How do I install the GMLAS driver, working with OGR command line tool?
Comment: OSGeo4W and packeges from gis.internals both come with GMLAS driver.
Answer: The GMLAS driver can not be installed. You need to install a GDAL distribution that has it built in.
The conda-forge gdal distribution includes the GMLAS driver. There may be other distributions that include it, but I only use conda.
If you don't have conda installed, I suggest miniconda.
<code>conda create -c conda-forge -n gdal_with_gmlas gdal python and any other packages etc
conda activate gdal_with_gmlas
ogrinfo --formats|findstr GML

  GML -vector- (rw+v): Geography Markup Language (GML)
  GMLAS -vector- (rwv): Geography Markup Language (GML) driven by application schemas
</code>


Can't connect as different user while accessing network share with in domain network in Mac

Question: Can't connect as different user while accessing network share with in domain network in Mac.
Through Go > Connect to server > connect as
Answer: I am having the same issue. I am logged in with userA. I can see all of the shares. I want to access a specific share that userA does not have access to that userB does. I disconnect from server, but 'connect as' does not do anything when I click it
I found a workaround:

Go to Finder
Click Go, then Connect to Server
Create a path of smb://userB@myserver

Source: https://discussions.apple.com/thread/7988659?answerId=31890794022#31890794022