Update from Loki to Hera stable?

Question: I was stuck with my first linux MacBook Pro (17" 2007 core2 duo era) with no possibilities to either read an USB other than MacOS and it didn't recognize my CD-RW for installing something else, so I wondered if it was possible after all to update from Loki 0.4.1 to Hera 5.1.
Answer: I can assure you that it is possible and that the result is great! Hera uses seemlessly (I didn't check) less ressources, runs smoother, and close lid suspend/resume is now working fine and fully supported.
Now please backup everything first, and take my word of caution: I did encounter a small error but it could be solved along the way, but you have to be ready to work it out in console-only mode. I really advise to do so to avoid upgrade issues.
I recommend to follow this post's green V'd reply
Nevertheless, I followed a simpler route than in the above post reply: I only backed up the indicated files in the post, but I didn't remove them, and I only did that and the update worked fine.
Look in advance for the way to log off graphical mode on Loki:
This worked for me:
session=`loginctl session-status | head -n 1 | awk '{print $1}'`
loginctl terminate-session $session

The error that I encountered is as follows:
libdvd-pkg: 'apt-get check' failed

to which I did only the following (which was then fixed by simply resuming the update process):
sudo apt remove libdvd-pkg

I had to reboot and install from console again, as in recovery mode (push escape on reboot to reach grub), and from the login screen (Fn+Ctrl+Alt+F1) to go to login, login and password then restart the apt instructions again to continue the upgrade. My screen blacked out repetively due to the login mode timeout, but I could see by (Fn+Crtl+Alt+F1) again as many times as needed. It's a little adventurous for the less experienced but it worked!
Don't forget to clean everything as the post indicates, by
sudo apt autoremove

Once the whole upgrade procedure is done.
The update goes straight from Loki to Hera.
Enjoy!

Update from Loki to Hera stable?


How can we write a contract that relies on hidden information?

Question: Since a smart contract can only access (public) information on the blockchain itself, how can I make a smart contract that relies on hidden / secret information? Are there any workarounds in this situation?
Answer: In simple terms, you can't.
In more complex terms, depending on your specific application, there are various forms of cryptography that you can use to achieve something similar to your desired objective, although most of the tooling around this crypto is still being developed.
Answer: Workarounds: Use whisper for hidden communication channels instead. Then at least you can send encrypted communication to some other person. (But, it's not seen a lot of development love.)
I'm not sure if things can be sent to/from a contract, I'd default to thinking no.
Answer: There are some research attempts here (Enigma) and here (Hawk) at maintaining data confidentiality in smart contracts:

In Enigma no single party ever has access to data in its
entirety.
In Hawk the blockchain is used to enforce the process in a
contract while limiting visibility of the state.

Neither of these are mature enough for public release (so won't really address your needs in the short short-term), and its also appears that both of the above result in some loss of generality.


Will Ukraine let me in if they see I've been in Russia first?

Question: I am planning a trip through Russia so I have to get the visa in my own country (Australia). But then I plan to go to Ukraine and I can get a visa upon arrival (if under 15 days). Is there  any risk that they would not allow me in? I'm just a tourist although I am of Ukrainian background and have relatives in Ukraine that I will be visiting.
Comment: Are you planning travel to Crimea?
Answer: There is no risk. Even Russian citizens are allowed to visit Ukraine, so why would somebody who has visited Russia be not allowed to enter the country?..
Comment: In addition, even citizens of Ukraine get to travel to Russia. Citizens of both countries can visit each other for 90 days visa free. So yeah, no risk as Neusser said!
Answer: Ukraine doesn't practice prohibiting people who have ever visited any other country entrance to its territory.
The only thing you should keep in mind is that if you'll during your visit to Russian Federation enter the occupied territories, such as the Crimean peninsula or part of Donbas behind so-called separation line from the Russian territory, it'll be considered an illegal border crossing and then you'll be either denied entrance to Ukraine or arrested.
Comment: And how would they know you've been to Crimea unless you try to cross from Crimea into Ukraine? I say there's nothing to worry about at all
Answer: You can definitely go to Ukraine after Russia, don't worry.
Note that visa upon arrival only for Australians exists at Ukrainian airports only, and not at the land borders, and that you need to fulfil the requirements for the visa-on-arrival.
Were you to get a visa before arriving to Ukraine, you could cross (to my repeated experience efficiently and hazel-free) overland from Russia. Do, however, stay clear of the Donbass and Crimea to which the dispute has had some profound implications for travellers.
Comment: Thanks. I also read on the Australian Department of Foreign Affairs website that "Children born in Australia to a Ukrainian parent are considered citizens of Ukraine by the Ukrainian Government. Anecdotal evidence suggests that tourist visas won't be granted to Australian citizens born in Ukraine or to Ukrainian parents." Have you ever heard of this happening?
Comment: @Lydia that is correct, but you'll need a proof of citizenship, e.g. passport of the national identity card.
Comment: Oh. Quite right. Maybe a separate question regarding tourist visas for descendants of Ukrainians citizens is in order?


GIMP doesn't show Tools window

Question: I have installed GIMP 2.8.4 on Ubuntu 13.04 (via standard repositories). My problem is I don't see Tools window (the one I used to show/hide with the Tab key). How can I make Tools window appear?
Answer: I have this problem as well. Sometimes the tools window is inside another screen.
Shortcut:
Ctrl + B
Try the following.

under the Windows tab click Single Window Mode
if the tools window isn't inside the main window, use the Windows tab  again and click Dockable dialogs  → Tool options.

If the tools and layer box didn't go inside your main gimp window  try toggling the Single Window Mode. This helps sometimes.
Comment: If the toolbox isnt there you can press "Control B" or you can under "windows" than  select option "ToolBox".
Comment: Also, make sure that you didn't accidentally press `Tab` because it is equivalent of `Windows -> Hide docks`.
Comment: Thanks, now I have my Tool Options back! That's quite a magic trick; did you figure it yourself?
Comment: No problem and Yes, a lot of playing around ha-ha.
Comment: But how do I make Toolbox appear?
Answer: From the GIMP menu select Windows -> Toolbox
Shortcut Ctrl + B
Answer: Make sure you don't have the Windows->Hide docks option enabled.
Comment: This one actually helped me.
Comment: Why is this downvoted so much?
Comment: This was my problem, been searching for ages. Thanks!
Answer: From GIMP 2.8.10, the menu changed a little bit:
From the GIMP menu you can open the toolbox in 2 ways:
Windows -> New Toolbox
Tools -> New Toolbox
Shortcut still works:
Ctrl + B
Answer: In my case, the problem was caused by trying to display Brightness/Contrast window on an index color profile which Gimp does not allow.  Switching to the single-window mode as illustrated in the accepted answer made the error message easier to find.  The solution was slightly different in my case: Convert the image to RGB via Image, Mode, RGB and then try again to show the Brightness/Contrast dialog.
Answer: If you are opening the Gimp Toolbox with Ctrl-B because you do not see it and after closing and restarting Gimp the Toolbox is not showing again, check that Windows > Hide docks option is not selected.
Unchecking this will allow the Gimp Toolbox to be shown on a new start.
Answer: Tab will show/hide "Docks". Or right click anywhere in the interface, which will bring up "Windows".. then everything everyone else said.
This was my issue.

GIMP doesn't show Tools window


What is the relation between 寨 (zhài, "stockade, stronghold, fort") and 塞 (sài, "place of strategic importance; pass; fortress")?

Question: Most dictionaries say 寨 = 塞 + 木, but on its face, we could just as easily have 塞 = 寨 + 土.
Answer: There doesn't seem to be much relation between「寨」and「塞」, although it takes some evidence to demonstrate why this is the case.

Firstly, the reason why many dictionaries say that「寨」is「塞」plus「木」is because「塞」is popularly but very likely mistakenly interpreted as the modern character for what was originally「賽」. The evolution of「賽」from oracle bone script to modern form is considered by some paleographers to be the following:

Basically, what appears as「工」in this character (and some others) is considered by several experts as a simplified form of「玉」, and sometimes was written as「玉」, while the two hands「廾」were sometimes removed in certain variants and「貝」was sometimes added as a semantic indicator. The character was a compound ideogram depicting the offering of objects to spirits inside a temple, and the primary meaning was to do with some kind of ritual, preserved in the ancient words「賽神」and「祭賽」.
As stated near the beginning, many important sources however say that the first two forms is the ancient form of「塞」(plug, fill in). For example:

段玉裁注:"凡填塞字皆當作。"

(「」is the second form in the evolution sequence depicted above. With a bit of stroke joining and simplification, 「」becomes「」, which is the top part of「賽」and the other characters mentioned in this question.)
Note that these sources, although traditionally very well reputed, do not appear to provide any paleographic or lexical evidence for this assertion, and so cannot be trusted for this specific character. Despite this, many dictionaries will follow these sources and treat「」as the original character for「塞」, and subsequently interpret「寨」as「」(mistakenly thought as 塞) plus「木」.

Interpreting the primary meaning of「賽」as a religious ritual, it is then very likely that「寨」and「塞」merely use「」(賽) as a phonetic component.

「塞」uses「土」as a semantic component to indicate the meaning stuff, plug, fill in. This is an ancient definition that has survived very well intact to the present. Note that the synonym「填」uses the same semantic component.
「寨」is only one possible form of the word it represents, the other commonly seen one being「砦」.
The only time when the two characters have anything to do with each other is for the meaning fortification.

Further reading:

季旭昇《說文新證》
于省吾《甲骨文字釋林》
何琳儀《戰國古文字典》

Please note that this explanation is tentative, and there will undoubtedly be differing opinions on these characters. More evidence is required to make a more solid case.
Comment: Very, very interesting post, thank you. BTW I'm having trouble grokking "「塞」is popularly but very likely mistakenly interpreted as the modern character for what was originally「賽」. "  You mean that what many people think is the original form of 「塞」 is actually the original form of 「賽」, right?
Comment: @Colin yes, that is exactly it.
Comment: I guess the hypothesis on the meanings would be 寨 has base meaning "stockade", whence "fort". "塞" has base meaning "stop up", whence (somehow) "pass, fortress".
Answer:
寨  (pinyin) zhai4
stockade; fence; stronghold; camp

The radical of 寨 is 宀 (#40), which means  屋頂 (roof), it describes a temporary or semi-permanent building structure for people to gather for specific purpose. For example, 营寨 (camp) 营 means 'camp' and there's no such thing as 营塞

塞  (pinyin) sai4
frontier; strategic stronghold along the frontier

The radical of 塞 is 土 (#32) , which means soil, it describes a permanent building structure of strategical importance. For example 要塞 (fortress) 要 means 'important', and 要寨 would mean 'important camp'

Basically, 塞 is a base and 寨 is a camp
Comment: my question is more about the similarity, not the difference. that is, are these meanings etymologically related and what is the etymological relation between the similar characters?
Comment: 寨 include 木, that indicate it is temporary or semi-permanent, when a 寨 became permanent, it change from  寨 to 塞 (木 to 土) to indicate it is a permanent base
Comment: any citation for that?
Comment: Chinese characters coining was basically exploring the extension of the  radical's meaning plus matching phonic components.  寨 and  塞 share the same phonic component but different radical gave them different meanings.
Comment: Similar example: 江 and 缸 share the same phonic component 工, but 江 (river) has  水(water)  radical and  缸  has 缶(container) radical.


GBP salary figure quoted but paid at open market rate in local Rs in Pakistan bank account

Question: GBP salary figure quoted but paid at open market rate in local Rs in Pakistan bank account. Do I lose out when considering my salary initial figure quoed in GBP but then received in Rs local currency calculated at open market rate each month?
Comment: They're not paying you in the currency they quoted your salary in? Weird.
Comment: @cHao the OP is living in Pakistan they are going to want to convert to the local currency - the OP could set up a dual currency account though
Answer: When getting a salary offer in a different currency, it is typical to negotiate based on the exchange rate as well.  Depending on the company, a standard exchange rate for accounting purposes is usually chosen for the year (if it is common for there to be cross currency transactions as part of the business).  Also, tax authorities typically give a yearly exchange rate to use.  I would discuss with your Manager, HR or Payroll and see if this can be worked out.  Remember that exchange rates fluctuate so you could either lose or win by freezing the rate, but the benefit is that it is predictable.
I should also note - that if you are doing work for a small company in the UK that does not have a corporate entity in Pakistan, and are wiring you the money each month from a UK account, then they may not be able to freeze the rate for you.
Answer:
Do you loose out ...

No you are not loosing out. Further the company may be transferring in GBP and the conversion may have been done by your bank


sklearn random forest and fitting with continuous features

Question: Does anyone know how the python sklearn random forest implementation handles continuous variables in the fitting process? I'm curious to know if it does any sort of binning (and if so, how it does the binning), or if a continuous variable is just treated as a categorical variable? I'm hoping it's not the latter...thanks! Also, I'd be open to using some R implementation if anyone knows about that.
Answer: To understand how a random forest treats continuous data it is imperative to understand how a random forest works. At the base of the random forest algorithm lays a tree construction. The default in sklearn is to split a tree based on the Gini coefficient (see sklearn documentation). This type of tree algorithm is referred to as CART trees. You can change the criterion to entropy to select ID3 and C4.5 trees. Without going to deep into the maths, the tree algorithm will seek to split the tree based on a cutoff that leads to the lowest Gini coefficient.
The random forest algorithm will build a large number of deep trees on your data and average over all the trained trees to give you the final prediction.
Depending on your requirements in terms of data size and necessity for parallelization I can highly recommend H2O. It is an open source machine learning software suite with APIs in Python and R. Their random forest implementation is very fast and leads to models with a higher AUC (see this page for a good comparison between different ML libraries).
Comment: Yeah, well i thought I understood decision trees lol. Does splitting based on Gini coefficient create a binary split? I thought decision trees didn't have to be binary?
Comment: Ok I read more about Gini impurity, and does only do binary splits. Thanks!


Where can I get circuits of interest to quantum chemistry to try and simplify?

Question: I am a computer science undergraduate working on a project in simplifying quantum circuits (using the ZX-calculus). I was hoping to try to simplify some circuits of interest rather than randomly generated circuits. I am uninitiated in the physics/chemistry. Where can I find ready-to-go circuits of interest or how can I easily generate circuits like this to try to simplify them?
Answer: In the paper A Generic Compilation Strategy for the Unitary Coupled Cluster Ansatz they benchmark on a bunch of chemistry circuits that can be found here. I should add that these circuits contain only a single Trotterisation step of the chemistry simulation. The actual simulation circuit would repeat this structure many many times.
Answer: You can create an account at IBM Q Experience for free here. After logging, go to Quantum Lab (incons on left-hand side, it is a fifth icon from top). Here you can find tutorials to quantum computing and Qiskit. There is also part called Chemistry. So, you can use example circuits presented here.
Answer: The Qiskit.chemistry is part of the Qiskit Aqua (Algorithms for QUantum computing Applications). The qiskit.chemistry package supports problems including ground state energy computations, excited states and dipole moments of molecule, both open and closed-shell.
The code comprises chemistry drivers, together with a molecular configuration will return one and two-body integrals as well as other data that is efficiently computed classically. The output data from a driver can then be used as input to the chemistry module that contains logic which is able to translate this into a form that is suitable for quantum algorithms. The following API reference would be very helpful to understand the sample Qiskit.chemistry circuits.
Answer: You can see the recent Google paper, but I have to say beforehand that this paper doesn't suit you. This paper requires familiarity with both the fields of quantum computing(to understand quantum circuit thing) and atomic-molecular physics(to understand the task and the Hartree-Fock method).
Maybe this qiskit documentation better suits you. With a background of CS, you should be familiar with the travelling salesman problem. But notes that this is another path of quantum computing, it focused on the Hamiltonian which depicts the time-evolution of the system while on the contrary, the quantum circuit acts on the state vector(or say qubits) step by step.
(Quantum annealing always using the time-dependent-Hamiltonian, I have not seen the Hamiltonian of this qiskit case but I guess this is in fact quantum annealing. But do not be that worry, quantum Turing machine, quantum circuit model and quantum annealer can be polynomially equivalent.)
I have to admit that this answer may not be that helpful to you.
Comment: There are many aspects of quantum computing, I myself haven't pay attention to quantum chemistry.


How do you set system display color profiles in Xubuntu and Lubuntu?

Question: Some applications, such as Gimp, Geeqie and Rawstudio claim to be able to use system color profile in their color management, but how do you setup such a profile? How do you see, if such a profile has been set, and if it has been set, how do you see which profile is used? I don't see how to do it in Lubuntu and Xubuntu.
Comment: You can now use `xiccd` to avoid the need for any Gnome/KDE/Unity dependencies when using `colord`;  http://askubuntu.com/q/427821/25639 explains how to install it.
Comment: Ubuntu 20.04 https://askubuntu.com/a/1464815/289138 - a success(?) story, still needs evaluation at this writing though.
Answer: This is a good question, as Xubuntu and Lubuntu don't have the same system settings > color menu that the standard Ubuntu has, and installing gnome-color-manager does not allow you to set the profiles in a Xubuntu or Xfce session, as you you can only use that utility properly when running a gnome session, as it depends on gnome-settings-daemon and gnome-control-center. This fact is clear from the useful diagram presented here in this article.
System Tools
However, on Xubuntu and Lubuntu, the colord package is still automatically installed and takes care of color management, and you can access it on the command-line using colormgr. You can query your devices such as printers and scanners by using command-line switches  such as colormgr get-devices, which are delineated at the official site.
However, while colormgr get-devices will list all the automatically color-managed devices on your system, it will not list display devices on xfce.
On xfce, colormgr get-devices-by-kind display will not work and you will not be able to set the icc profile for the display on the command-line, but only by using tools such as xicc or xcalib (see further below). This is explained here by Richard Hughes:

XFCE has no session component for colord. You need to either run gnome-settings-daemon (which has a color plugin), kded with colord-kde installed, or write something lightweight for XFCE.
Colord only detects system devices like scanners and webcams, and then CUPS registers printers. It has no access to the session, and relies on a session component to talk to X and register devices.

In a gnome or kde session (which you could be running on Xubuntu) you should be able to use colormgr to enter colormgr get-devices-by-kind display and set the icc profile for the display manually, so for completeness I present this method.
You first have to add your profiles to ~/.local/share/icc and run colormgr get-profiles to list them, and then choose the icc profile, such as
/org/freedesktop/ColorManager/profiles/icc_86894053ff74b24d0c304fc3bd0e9c76

Now add it to the desired device (this time it is the default display) with
colormgr device-add-profile /org/freedesktop/ColorManager/devices/xrandr_default /org/freedesktop/ColorManager/profiles/icc_86894053ff74b24d0c304fc3bd0e9c76

Then you can make it default with
colormgr device-make-profile-default /org/freedesktop/ColorManager/devices/xrandr_default /org/freedesktop/ColorManager/profiles/icc_86894053ff74b24d0c304fc3bd0e9c76

Other useful Utilities
Note: Custom icc profiles should go in /home/$USER/.local/share/icc; the system directory is /usr/share/color/icc.
It is possible to use tools such as xicc or xcalib if you want to setup a specific icc profile on Xubuntu or Lubuntu. All you need do is point either of these tools at your icc profile and place that command in startup:
xicc /location/of/profile

or with xcalib you can specify gamma correction as well using
xcalib -gc 1.8 /location/of/profile

However, as the question below shows, you may need to delay the execution of the command so the system does not override your choice:

How to make xcalib always start up automatically?

Alternatively, you may want to use xicc, as the profiles set with that application are designed to be picked up by certain applications such as Gimp- this is exactly what you refer to in your question, and this program is probably what you were thinking of. To load a profile, just run xicc /location/of/profile; you can specify the display if necessary.
The package notes for xiccexplain that

This utility lets you set an ICC colour profile for an X display, so that
   applications can use it to display colour calibrated images.  Applications have
   to specifically look for this atom but several applications such as Gimp and
   Krita already do.

Alternatively, you can usually set profiles explicitly in applications such as the Gimp (see screenshot below) and other programs. This may be necessary if you are working with RAW images that may demand a specific colorspace.
Comment: It seems to me that xcalib and xicc are not alternatives to each other, but they complement each other: xcalib sets X server gamma ramp according to data that may be included in the provided ICC profile, and that setting has effect regardless of applications, whereas xicc sets system display profile that may or may not be applied by applications.
Comment: Thank you for diverse answer. As for xicc, I wonder what kind of "atom" do they mean. Is it just the system monitor profile option that is displayed in the screenshot?
Comment: I get no output for `colormgr get-devices-by-kind display`. I guess that indicates that system display profile is undefined.
Comment: @jarno see my edit re `colormgr` on xfce systems.
Comment: It might be difficult to apply different settings for different monitors, if you use extended desktop: In my setup xcalib changed settings for the integrated monitor of my notebook only and I did not find a way to set calibration for an external monitor, when extended desktop is in use. I didn't test xicc in this respect, but I guess it is the same.
Comment: @jarno That's an interesting point, and it would make a good, separate question to ask, as you did not specify this factor in the original question.
Comment: jarno, see http://www.darktable.org/2013/05/display-color-management-in-darktable/ So there are two parts to a profile, the vcgt (whole-screen gamma+whitepoint) and "the rest" (which individual applications use, and is set in the _ICC_PROFILE atom – check if set with `xprop -display :0.0 -len 14 -root _ICC_PROFILE`)
Comment: Be careful about `colormgr`. I tried tools mentioned here on Xubuntu 13.10. After I played with `colormgr device-add-profile /path/to/device /path/to/randomprofile` not only could I not see any change, but I got `gnome-settings-daemon` permanently broken for all users on the machine. Launching it would crash immediately with `color-plugin:ERROR:gsd-color-manager.c:905:gcm_session_device_assign_profile_connect_cb: assertion failed: (filename != NULL)` .
Comment: I could fix the permanently broken `gnome-settings-daemon` problem by killing `colord` and moving away `/var/lib/colord/mapping.db`. That file is a SQLite3 database where `colormgr` has `colord` record device-to-profile associations. Hope this may help similar cases.
Comment: so can I start a Gnome session, calibrate, save the calibration, and then have it load and work in a xfce (or other) session?
Answer: As an alternative, there is an excellent german howto all necessary things manually: http://wiki.ubuntuusers.de/Monitor_profilieren_mit_ArgyllCMS
Answer: I've just tried to work through this on Lubuntu 17.04 so this is how it worked for me. My Lubuntu system is on an old Dell laptop primarily used for emails and internet browsing with Firefox.
The first priority was to get Firefox colour managed. Fortunately it can be done in the application alone. Navigate a Firefox browser window to

about:config

and after the warning page search for

color_man

this will list the colour management properties for Firefox. Set display_profile to the location of your icc profile. It should be located in your ~/.local/share/icc/ directory ie

/home/user/.local/share/icc/my_screen_profile.icc

If no profile is set here Firefox will try to use the system profile, but we've got none set yet. Se enablev4 to

true

to allow v4 profiles. Set mode to

1

where 0 = disable colour management, 1 = enable for all rendered graphics, 2 = enable for profile tagged images only. Set rendering_intent to

0

where  0 = perceptual, 1 relative colormetric, 2 = saturation,3 = absolute colormetric. Restart Firefox and you are done. Test your browser by going to color.org. There is one problem here though. Whilst the browser is colour managed, the pdf preview isn't. You can check this out with the pdf version. If you send the file to the default pdf viewer Evince Document Viewer 3.24.0 it is rendered correctly though.
Firefox settings taken from NTown Productions
Although this is probably adequate for what I need, this wasn't he solution I was after so further research and a slow Sunday led me to the following which sets up colour management for the system.
Login in to synaptic and install

colord

and

xiccd

If I was doing this first, without having set up Firefox I can open a terminal (ctrl+alt+t) and use colormgr to import my display profile from any location into ~/.local/share/icc/ like this

colormgr import-profile /home/user/Downloads/my_screen_profile.icc

Be careful with filenames. I had problems with white space in the filenames I created making the profiles with Argyll / DisplayCAL. It seemed best to keep the filenames short and simple. For some reason I have to run this command more than once. The first run copied the file into my icc directory, the second run actually imports the file into the colord system and reports back with a summary of the profile including meta and the profiles "object path". Next we can check that xiccd has allowed colord to interact with the display with the command

colormgr get-devices-by-kind display

This returns a summary which includes the display device's "object path" required for adding the profile with the command

colormgr device-add-profile "display device object path" "profile object path"

The object paths are long so I used shift+ctrl+c to copy and shift+ctrl+v to paste in my terminal window. If you run

colormgr get-devices-by-kind display

again you should see your profile in position 1) making it the default profile. If it isn't or you want to change the default use

colormgr device-make-profile-default "display device object path" "profile object path"

and removed with

colormgr delete-profile "display device object path" "profile object path"

Other options can be found from

colormgr --help

To test this I used this method rawpedia and the extracticc command from the argyll package on the jpg with the mixed up sRGB profile on the color.org page, then added this to my display in the same way as above. I then blanked out the display_profile setting in Firefox prompting it to use the system profile on restart. The browser now displayed sGBR ie red for green and vice versa.
Other references in addition to the answer above by user76204
ArchWiki
pcode
All offer similar advice but did not quite work on my system.
Note. The default image viewer in Lubuntu 17.04 is GPicView which is not colour managed, so use synaptic to swap it for eog or eye of gnome image viewer.


According to "proper speech" in Buddhism's eight-fold path, is cursing allowed if it's necessary to get the point across?

Question: One of the points of Buddhism the eight fold lists "proper speech," but does this propriety in speech include the ability to insult others or express yourself strongly through the use of curse words/ cursing if it's necessary to get the point across to someone who wouldn't get the point otherwise? Why/ why not?
Comment: If  you have a question specifically about Buddhist practice, there's an SE for that. If you have a question about what "proper speech" means in philosophy, it could potentially be on-topic here (but I don't see it in this case). If you @virmaior me that you want it there, I can move it for you.
Comment: @virmaior Edit if you like, and send it over to buddhism.stackechange for me?
Comment: There is a whole range of what might fit into your scenario. An example or two would be helpful.
Comment: @user3169 without cursing myself, the "F" bomb, calling someone an "a-hole" that type of a thing
Answer: One of the Five Precepts (pañca-sila) - the basic training rules that is observed by all practicing Buddhist lay men and women -  is to follow the precept of abstaining from wrong speech. Wrong speech involves a great many things apart from uttering falsehoods. It includes insulting speech, malicious speech, even gossip.  This in positive terms is the practice of Right Speech.  It is said that "If you can't control your mouth, there's no way you can hope to control your mind." This is why right speech is so important in day-to-day practice.
Cursing if it's necessary to get the point across to someone can be termed as harsh speech (spoken with the intent of hurting another person's feelings). The important point is that you were mindful of this slip. I do not see it as a transgression. It is not a sin as that of a transgression against a god, as in other faiths. This is only a trifling unwholesome act done by one who strives to practice the Dhamma, as opposed to the same act by another. What I said above is in keeping with the scriptures.

"Suppose that a man were to drop a lump of salt into a small amount of water in a cup. What do you think? Would the water in the cup become salty because of the lump of salt, and unfit to drink?"
  "Yes, lord …."
  "Now suppose that a man were to drop a lump of salt into the River Ganges. What do you think? Would the water in the River Ganges become salty because of the lump of salt, and unfit to drink?"
  "No, lord …."
  "In the same way, there is the case where a trifling evil act done by one individual [the first] takes him to hell; and there is the case where the very same sort of trifling act done by the other individual is experienced in the here & now, and for the most part barely appears for a moment."
  — AN 3:99
Answer: See this answer for some references to definitions of "right speech", but also "wrathful Buddha".
Assuming that the situation is as the question was phrased, i.e. "if it's necessary", then the answer might be yes it's allowed. This answer gave a (hypothetical and extreme) example of where even lying could be allowed (well not "allowed", exactly, but preferred as the lesser of two evils).
It might be especially allowed in Mahayana Buddhism, which maybe has more of a tradition of "skillful means" (doing something because it's necessary in practice, not because it's theoretically correct).
The concept of a "wrathful" Buddha (which is again, I think, especially a concept taken from Mahayana/Tibetan Buddhism) reminds me of some parents who said once that their children "would never take the boats out without permission: because they know that we would murder them" (the point of the story being that the boats and tides were dangerous for small children, and though the parents' wrath seems to or even claims to threaten the children, it is actually intended to protect them).
Still the number of times when you think it's necessary, versus the number of times when it's actually necessary might be very different -- i.e. it might be (too) easy to justify misbehaviour ("it's necessary ... I want to ... everyone does it"). This is where it might be useful to have a good role model to emulate -- maybe you know a good parent or teacher who would never insult people or use curse words?
Also FWIW I think that "proper speech" appears in two places: it's the fourth of the precepts, and the third factor of the Noble eightfold way.
I think that the precepts seem to be especially focused on social or inter-personal harmony, whereas the eightfold way is especially focused on your own personal perceptions. So maybe these are two/both reasons for "right speech": to promote a well and harmonious society, and as a means towards avoiding being upset yourself.


Need to identify plants

Question:  I have 2  plants I got as gifts and don't know how to care for them. Anyone have any idea what they are? One has thick. Curved leaves, if you can even call them that. It has a layer of short, fur like stuff that goes all over the leaves. Growing upward with a thick, tree like stem. It's about the size of a hand. No idea what it is.
Second one I have has leaves similar to a succulent I have but the stem has a bark like layer and the stems are long, with a head of green thick, stiff leaves that look like a echeveria plant but I don't think it is. I can't add pictures because apparently they're too large? I'll try to add in the comments maybe after but if anyone knows something that partially matches these descriptions it would a a place to start for me.
Comment: Welcome! If you have two different plants, please post _two_ questions! If you have problems with photos, one of the most common causes is image size - try to stay under 2 MB.
Answer: I'm pretty confident that the pictured plant is an Aeonium of some kind. The keys are

The upright "trunk" and branching
The flattened rosette of leaves at the end of each "stem"
The way in which the leaves whorl about the center in each rosette
The leaf shape

If this is an aeonium, then care is relatively easy, beginning with "DO NOT OVER WATER. Here's more information, from the site World of Succulents:

Try to keep the plant at a temperature around 65-75°F (18-24°C), which mimics winter in their native habitat. If it gets too hot they may go dormant.
Water only when the soil is completely dry down to a depth of at least one inch/2.5 cm.
After watering, remove any water that's in the saucer after maybe 15 minutes or so.
Feed only during their growing period with half-strength balanced fertilizer.

It's currently in a great pot - clay with a drainage hole. When it is time to transplant (after 2–3 years in the pot) use a regular potting mix because they do like some moisture in the soil.

Need to identify plants


How many Collectors (Probe/Drone/SCV) do you have to kill for a raid to be worth it?

Question: So frequently, I find myself raiding the enemy base with some fast harasser unit (example: Mutalisks) and I find that the enemy mineral line is defended in some way (example: marines/photon cannons).  Now I know that each Mutalisk costs me 100 crystal and 100 gas, but I also know that each Collector costs my opponent 50 crystal + all the resources it will ever collect for the rest of the game.  So the question is, how can you determine how many Collectors you should kill for some value of raiding force for the loss of the raiding force to be 'worth it'?
Comment: I don't believe this is a constructive question. Alot of speculation can be brought up on this answer
Comment: Really hard to formulate an answer for this because there are so many factors. If the harass units don't die, then they have lots of other uses to help make them "worth it". But ultimately, during the game, "worth it" is not relevant. Do as much damage as you safely can, and get out. If it wasn't worth it, it doesn't matter; continue with the game. Like in chess, don't bother thinking about previous moves; evaluate the board as it currently sits.
Comment: Correction: collector costs 50 crystal + all the resources it'd collect until replaced. "Until end of game" would only be true if it's owner would build collectors without limit or delay until the end.
Comment: Yeah, probably needs some narrowing down.
Answer: The mechanics and mathematics behind certain strategies can be discusses for days upon end in Starcraft. I like to take a different route when giving advice to friends.
Psychology.
How many times have you ragequit from a match because you felt defeated and then went back to view the replay...and found out that if you had retained a cool head, built up your economy/units and counterattacked, you would have won easily?
Forcing your opponent to feel like they are losing the game (whether they are actually losing or not) can turn the tide more than crazy APM or micro.
For example: With an MMM build, Terrans are afforded huge map control and harassment potential. The ability to drop your Marines and Marauders in a key location (such as the enemy mineral line), keep them healed up, and get away unscathed will wear at your opponent greatly over time, giving you openings to take advantage of your opponent's mistakes. They might overproduce military units, allowing you to take the economic advantage. Your foe might overcompensate with drop defense and take too many units back to defend the line, giving you a clear avenue to attack straight-up.
My answer is this: Forcing your opponent to feel disorganized, frustrated, and off-balance is worth a hell of a lot more than several times the cost of a few units thrown out to die.
Answer: This is a relatively open question, because there is a big variety of raids. Doing the math is far beyond my ability/motivation level as well, so my answer is mostly subjective. Let's divide this into several cases:

An early game raid. This contains mostly mineral units and is done when the enemy has a single base (or two, if they're playing early expand). Minerals for drones are still relatively limited, making them highly valuable. I'd argue that killing even a third of the drones' cost compared to the force you lose is an even trade. If you're using three upgraded hellions for example, their cost would be 3x100+1x150, plus 150 gas, which could be converted to about 500 minerals. Thus, for the raid to have been worth your trouble, you would want to have killed at least 7 drones. The same calculation applies if you're using a dropship, as you are unlikely to use it, and it can be integrated into your army composition. The raid itself is a risk - it's harder to survive while teching for hellions and it costs more APM than a more orthodox approach, and you also want to win, not to make even trades. Thus, while 7 drones is "sufficient", it's far from enough. Additionally, you don't really want to lose the hellions - while it's tempting to suicide them and never worry about the fragile speedsters again, pulling them out at the right time will put your opponent on edge, force him to watch his back, and let you reuse them on some unguarded expansion later in the game. This is doubly true for early-game raids with less gimmicky units which can immediately join your standing army, provided they are fast enough to escape.
A late game raid. Mechanics here are completely different. Drones cost less, because they can be replaced much faster, leading to significant decrease in the long-term yield decrease, so much that it becomes a short-term yield decrease. You'd also likely be killing inefficient "third" drones, which have a reduced yield to start with (saturation). The rule from the previous situation applies doubly - try to save your raiders. Also heavily consider the gas and APM costs, as these resources are the main limiters at this stage of the game. A marine drop is cheap on gas, can assault any undefended expansion, and is easy to pull out - it is also heavy on micro.

tl;dr: Pull out early, losing raiders is a failure. You should only be killing drones when you're not being shot upon by a superior force, and if one approaches, retreating in time and coming back later/attacking another base is better than trying to get just one more drone (reminds me of the sunk cost fallacy, because you aren't sacrificing a drop for ten drones, you're sacrificing it for the last two that you wouldn't kill if you retreated early, a fact that makes any wiped out harass with sufficient unit mobility a failure). For land units in the early game that can't survive a raid (speedlings that end up in the mineral line because the enemy army was having a field trip somewhere), killing a third of their cost in drones should end up as a (subjectively) even trade. For a similar situation in the end game, drones become only as valuable as normal units, sometimes even cheaper, and the only way for harass to have a significant effect is for it to happen multiple times, killing off the drones in many enemy bases consequtively.
Comment: also the race, for example a zerg player in late game can replace all the drones in one round one round, protoss and terran have to wait for the tail, i think terran get more trouble with the workers and zerg with the buildings
Comment: You're right of course, though the difference is somewhat marginal. The larva loss may or may not also slow the Zerg army production - I have no clue, as I played Terran back when I was active. Those are both small differences which shouldn't affect the harasser's decision-making.
Answer: It depends a lot from the type and the number of units you use for harass.
For instance, a pack of 7 mutalisks must kill a lot more that 10 zerglings to pay for itself.
I think a good rule of thumb is you have to kill for the same amount of resources your harass units cost you. For instance 10 zerglings => 5 collectors, 8 mutalisks => 32 collectors (and/or 1600 worth of resources of pylons/overlord/depots, tech, production, ...)
The value of a good harass is also that it allows you to force your opponent into defense mode, which allows you to expand, attack elsewhere while he backs to defend, etc. This cannot be evaluated in terms of kills.


How do black holes evaporate?

Question: Will black holes evaporate, if they evaporate? When and why do they evaporate? What are the conditions for evaporation? Under what principle do they evaporate?
Comment: http://en.wikipedia.org/wiki/Hawking_radiation
Answer: The evaporation occurs through Hawking radiation. This is a very slow and low energy process. So low that the cosmic microwave background radiation, which is just a few degrees above absolute zero, pours far more energy into the black hole than Hawking radiation takes away. So in principle a black hole cannot evaporate.
With the exception of conjectured atomic sized black holes, that is, as Hawking radiation would be more pronounced then.
Edit: See this answer on the physics SE: https://physics.stackexchange.com/a/26607/55483
The black hole would need to be less massive than the moon to radiate more energy than it absorbs. Bigger than atomic size, as I suggested.
Comment: @HDE226868 I found a similar question and answer on the physics SE, and added a link to it in my answer.
Comment: @Dilaton Which part is incorrect, then? What you say is what that answer says, so I'm not sure what is being disagreed with.
Answer: hawking radiation. electrons and positrons created from the vacuum must 'repay' their energy, usually through annihilation of each other. however, if one crosses through the event horizon of a black hole and the other escapes, the energy from the black hole as well as that of the particle will 'repay' and the escaped particle becomes real. this is a very slow process and in most circumstances I would assume that a black hole would accumulate more energy than it loses.
Comment: I don't think they are electrons and positrons but virtual particles.

How do black holes evaporate?


Resources to translate official French documents (diplomas, birth certificate, etc.) into English

Question: When filing visa applications in the United States, one sometime needs to provide certified translations of official documents from the country of birth. Is there any online resources that would give translation templates or examples for French official documents such as birth certificate, diplomas, or transcriptsm into English?
Comment: If you're in America, find a Notary Public which offers translation services (not all of them do). Sometimes this can be found at the DMV, but usually you'll have to google to find a notary which is capable of translating from French. DMV notaries just do certified copies, usually. You will need both a translation and a notary certification. Anyway, can give a comprehensive answer if you state your location.
Comment: Are you in France? If so, apostille / transducteur are the usual go-to for this, but they are expensive.
Comment: @lafemmecosmique Thanks, I am located in the United States (Massachusetts). For the visa application that I am filing, I am allowed to do the translation myself (I just need someone proficient in both French and English to sign the translated version). But I am trying to do a decent job at it, and I was hoping some online resources could help me [save time](http://ell.stackexchange.com/q/81989/3023).
Answer: There are plenty. I used REV, but there are countless other similar services.
That said, "certified" means the translator certifies that he/she knows both languages well enough to translate, and that's it. Rarely you'd need an official or notarized translation in the US. So if you have a friend who's fluent in French and English - they can do the translation for you, and certify that they know the languages well enough. Here's a USCIS example for a certification.
Comment: @FranckDernoncourt I suspect they have enough speakers of whatever language that may be, and as far as I know there's no concept of notary in the US which is similar to what you're used to from Europe.
Comment: Thanks. I guess I was hoping for a free pool of templates / examples, since as you said no need for an official or notarized translation, which is great as I'd save me a few hundreds USD. Side note: do you know why USCIS rarely asks for official or notarized translation?


I can't be 100% sure I'm asking this question

Question: I like to believe one can't be 100% sure of anything, for one can't be 100% sure their brain functions correctly (because if it doesn't, it may mistake itself as functioning correctly as a result). Is there a name for and/or existing material on this theory?
Comment: @JohnAm "according to radical skepticism you can't really say it". This is incorrect. Radical skepticism only claims that you can't know if you really say it.
Comment: @JohnAm No - the OP might be pugged into the Matrix, with an Evil AI make them think that they are doing all of these actions.
Comment: @ Alexander S King You are saying something. But according to radical skepticism you can't really say it. So at the end "you" and radical skepticism says nothing at all.
Comment: There is a nice ring of paradoxical self-reference to "Am I asking this question?" similar to "This sentence is false". Logicians made a lot with the Liar, perhaps there is something to Puzzler too.
Comment: Actually, for Sextus Empiricus, you shouldn't be sure that you don't know whether or not you said it.  You should suspend judgement until someone cares, and then act as if they are right, just for your own peace of mind.  Bothering to consider it, before knowing it is mandatory is already too arrogant for a real skeptic.  And of course you can't get to the knowing it is mandatory point without bothering to considering it.  So, Zen.
Comment: @Elyse: if you cannot be sure of anything, then you cannot even be sure that you cannot be sure of anything. Thus, why believing it with certainty ?
Answer: I am going to disagree with the "radical skepticism" label. "Not 100%" is very far from "most likely impossible". That certainty is never justified can also mean that it is 99% justified 99% of the time, and I would call that rather overconfident. Depending on specifics OP stance can describe a variety of positions including Quine's empirical holism for example: any claim is subject to future revision in the face of recalcitrant experience, there are no a priori certainties. About 50% of contemporary analytic philosophers subscribe to naturalized epistemology, and they are hardly radical skeptics.
Answer: Radical skepticism is the term you are looking for. Descartes Meditation is an early work that starts from this position.
Answer: The name for this position is radical skepticism: the idea that no knowledge will ever be certain. DesCartes tried to disprove it with his "I think therefore I am", Hume talks about it. It is one of the central problems of epistemology.
Answer: Pyrrho got there long before Descartes, and stayed in the vein for a longer time before betraying its basic principles.  Sextus Empiricus' rearrangement of Pyrrho is the closest thing we still have.
Descartes only wishes he could manage to be a radical skeptic.  I don't think the natural exit point from true radical skepticism involves three separate proofs of God, and all the other trappings of Descartes.
And as for all the disparaging comments.  Bear in mind that major world religions, including branches of Hinduism and Buddhism think it is important to be radically skeptical, at least on a theoretical level.
Comment: Question everything does not equal do nothing.  1) There is a whole continuum of productive interpretations of radical skepticism when it is rolled up in these faiths from 'always keep an open mind' to 'this is all evil trickery, hide from the world'.  (You seem to imagine it always means the latter.)  2) Some religions are actually pretty rational compared to what philosophers say.  (Zombies?  really?  Get over it.)


What are Reiju's powers

Question: In the Wholecake island arc, Reiju was able to suck out poison from Luffy's body. How come? Wasn't Impel Down's Magellan the one who ate the Poison-Poison fruit? So what are Reiju's powers?
Comment: check [this](http://onepiece.wikia.com/wiki/Vinsmoke_Reiju#Abilities_and_Powers), about **poison pink**
Comment: @kaz - I just said that we know that Magellan is the one who ate the Poison fruit
Comment: @mirroroftruth - post an answer to accept it
Comment: That's one of the issues of the Germa characters. We know that their powers don't come from Devil fruits but from experiments and technology, though it is possible that she may have a fruit as we haven't seen her in waste high water to know if it affects her. In the next issue I'm expecting to see more combat panels from the Germa characters and maybe I can answer then.
Comment: That doesn't mean anything, so what he ate the poison fruit. There are tons of possibilities that she has a negation fruit, a heal fruit, a drain fruit, or some other fruit power that let's get absorb parts of  some one else. All of which can be associated to fruits
Answer: Till now(manga chapter 883) we don't know about the devil fruit that Reiju ate, but as described in one piece wika

Possibly resulting from her genetic enhancements, Reiju wields considerable poison-based powers, which garnered her the epithet of "Poison Pink."She can suck poison out of people via mouth-to-mouth and ingest it, while having exhibited immense immunity to the most virulent of poisons, such as extremely lethal doses of the poison from an Armored Stonefish's skin, as shown when she saved Luffy.

And

Reiju is also capable of secreting poison from her body and combining it with physical attacks.

That may be the reason why Reiju was able to suck out poison from Luffy's body and had no effect on her body.
Comment: According to One Piece Magazine, Reiju did eat a Devil Fruit. We simply don't know yet if her ability to suck out poison is possible thanks to it, or her genetic experiments.

What are Reiju's powers


How to transferFrom an external erc20 token with IERC20?

Question: Currently, I try to send Wrapped ETH from my account to a contract address by using IERC20. But it returned an error on Remix. By the way, I could call token.balanceOf(msg.sender) but can't execute token.transferFrom(msg.sender, address(this), amount) somehow.
My code is below
pragma solidity ^0.6.0;

import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.0.0/contracts/token/ERC20/IERC20.sol";

contract Test2 {

        IERC20 public token;

        constructor(address _token) public {
        token = IERC20(_token);
        }

        function getBalance() public view returns(uint) {
            uint balance_ = token.balanceOf(msg.sender);
            return balance_;
        }

        function deposit(uint amount) public {
            require(amount <= token.balanceOf(msg.sender), "you don't have enough balance.");
            token.transferFrom(msg.sender, address(this), amount);
        }

}

And ERC20 token I want to send is Wrapped ETH. So I copied the WETH contract and deployed on Remix before I deployed this contract. And when I deploy the above contract I add deployed
WETH contract address as an argument of the constructor.
The error message is always like below on Javascript VM on Remix IDE. But this error message doesn't tell what the real problem is. making my contract payable doesn't make sense and I checked that the balance I own is always more than I want to send.
VM error: revert. revert The transaction has been reverted to the initial state. Note: The called function should be payable if you send value and the value you send should be less than your current balance.
WETH contract is here but actually which erc20 I use doesn't matter because I tried the same thing with other deployed ERC20 tokens and even external LINK contract on the Ropsten net (https://ropsten.etherscan.io/address/0x20fe562d797a42dcb3399062ae9546cd06f63280)

contract WETH9 {
    string public name     = "Wrapped Ether";
    string public symbol   = "WETH";
    uint8  public decimals = 18;

    event  Approval(address indexed src, address indexed guy, uint wad);
    event  Transfer(address indexed src, address indexed dst, uint wad);
    event  Deposit(address indexed dst, uint wad);
    event  Withdrawal(address indexed src, uint wad);

    mapping (address => uint)                       public  balanceOf;
    mapping (address => mapping (address => uint))  public  allowance;

    function() public payable {
        deposit();
    }
    function deposit() public payable {
        balanceOf[msg.sender] += msg.value;
        Deposit(msg.sender, msg.value);
    }
    function withdraw(uint wad) public {
        require(balanceOf[msg.sender] >= wad);
        balanceOf[msg.sender] -= wad;
        msg.sender.transfer(wad);
        Withdrawal(msg.sender, wad);
    }

    function totalSupply() public view returns (uint) {
        return this.balance;
    }

    function approve(address guy, uint wad) public returns (bool) {
        allowance[msg.sender][guy] = wad;
        Approval(msg.sender, guy, wad);
        return true;
    }

    function transfer(address dst, uint wad) public returns (bool) {
        return transferFrom(msg.sender, dst, wad);
    }

    function transferFrom(address src, address dst, uint wad)
        public
        returns (bool)
    {
        require(balanceOf[src] >= wad);

        if (src != msg.sender && allowance[src][msg.sender] != uint(-1)) {
            require(allowance[src][msg.sender] >= wad);
            allowance[src][msg.sender] -= wad;
        }

        balanceOf[src] -= wad;
        balanceOf[dst] += wad;

        Transfer(src, dst, wad);

        return true;
    }
}

Please help me if you know what the problem is! thanks!
Answer: Let's take a look at this method:
token.transferFrom(msg.sender, address(this), amount);

What the contract does is transfer a quantity amount of WETH token from the caller of the function (msg.sender) to the contract (address(this)).
Now let's see the transferFrom method.
The causes of transaction failure are as follows :
        if (src != msg.sender && allowance[src][msg.sender] != uint(-1)) {
        require(allowance[src][msg.sender] >= wad);
        allowance[src][msg.sender] -= wad;
    }

In your Test2 contract, the caller of deposit is the user who interact with the contract. However, the caller of transferFrom is the contract itself, not the user. Then msg.sender is not the same in Test2 and WETH9 contracts during the transaction execution. The user must therefore approve the Test2 contract to allow it to transfer their token.
See this for more information : Approve contract to withdraw funds from users's wallet
Comment: Thanks, I could let the contract send call the WETH contract and transfer my funds.


Setting up bleed/margin for printing

Question: I have to create a 400 page book with the measurements height: 16cm by 24cm in Adobe InDesign. It is intended for publishing, but what are the bleed and margin measurements I need to follow so that it can be printed correctly?
Comment: Hi Alexandra. Thanks for your question and welcome to GDSE! I don't think there is going to be a 'correct' answer to your question, as bleed is up to your printer (contact them, I'd say), and margin is up to you, the designer.
Answer: In general...
Bleeds should be a minimum of .125 inches, 9 points, or 3.2mm.
Margins or "safe area" are often set .25 inches, 1p6 picas, or 6.5mm inside the trim.
These are general measurements which I've found will work for 99.9% of the print providers I come across. However, as Bakabaka posted in the comments, each printer can have a different set of preferred measurements. You should ask for general specifications from your printer if that's possible.
For example, some publishers want single pages with no inside bleed/trim. So the bleeds are not the same on all 4 sides of the piece.
Answer: A large book will not be printed page by page in a reader's spread. Most likely, it will be imported into a page imposition program that will print several pages at a time in what is called a signature or a printer's spread. Printer's page imposition is specialized software that allows for stuff like page "shingling" and "creep" and positioning of pages according to the desired print finishing to be performed. The various settings for InDesign should originate from the one who will impose your files for book printing. Assume nothing and get your information from the book publisher's printer. Ask for a "JDF" (Job Description File). It will come in the form of a disk with instructions. It will put all the correct values into the right places for your software to work correctly with the print publisher.
C'mon back if there's no printer yet chosen.
There are loads of different ways to determine margins for a book. Have a peek at anything by Jan Tschichold. Proportional margins usually have the gutter roughly equal to the sides and the upper to be half the lower. After that, there are hundreds of variations.
Comment: While everything you posted is true, I'm still left wondering, how does explaining imposition answer the question?
Comment: @Scott Apologies. It was an over-long, over-detailed, variation of "Go ask your mother." I was attempting to frame why one would consult the printer for all details that might affect the production of the publication. Since you covered the standard settings, I was amplifying what happens in the production.

Setting up bleed/margin for printing


Mathematical foundations of the ability to learn

Question: I am an undergraduate student in applied mathematics with an interest in artificial intelligence. I am currently exploring topics where I could do research. Coming from a mathematical background I am interested in the question: Can we mathematically establish that a certain AI system has the ability to learn a task given some examples of how it should be done?
I would like to know what research has been done on this topic and also what mathematical tools could be helpful in answering such questions.
Answer: Computational learning theory (or just learning theory, abbreviated as CLT, COLT, or LT) is devoted to the mathematical and computational analysis of machine learning algorithms, so it is concerned with the learnability (i.e. generalization, bounds, efficiency, etc.) of certain tasks, given a learner (or a learning algorithm), a hypothesis space, data, etc.
CLT can be divided into two subfields:

statistical learning theory (SLT) and
algorithmic/formal learning theory (ALT), which is the nonstatistical approach to CLT

The most famous and studied SLT frameworks might be PAC learning and the VC theory (which extends PAC learning to infinite-dimensional hypothesis spaces).
There are many good resources on CLT, some of which can be found in this answer.
Here's a related question on this site: What sort of mathematical problems are there in AI that people are working on?.
Answer: @nbro has already provided a great answer, so i'll just supplement his answer with two specific results:
Minsky, in his 1969 book Perceptrons provided a mathematical proof that showed that certain types of neural networks (then called perceptrons) weren't able to compute a function called the XOR function, thus showing that the mind couldn't be implemented on strictly this structure. Minsky further argued that this result would generalize to all neural networks, but he failed to account for an architectural adaptation known as "hidden layers", which would allow for neural networks to compute the XOR function. This result isn't very relavant in modern times, but the immediate impact of his proof lead to several decades of people ignoring neural networks due to their perceived failings.
Another commonly cited result is the Universal approximation theorem, which shows that a sufficiently wide single layer neural network would be able to approximate (read as: arbitrarily close) any continuous function given appropriate activation function (iirc the activation needed to be non-linear).
You can also consider the research of MIRI, which in a sense is more of a "pure" study of AI than the examples listed above. Their Program Equilibrium via Provability Logic result was pretty interesting, the gist of that paper is that programs can learn to cooperate in a very simple game if they read each other's source code.


Smooth shading with nodes?

Question: I'm currently trying to build an Anime style shader in blender and edit the normals to get better shading. But i also want a fresnel effect thats not effected by the edited normals. i know there is this true normal output on the geometry-node, but it gives me just the flat shaded normals. So, does anyone know a way to smooth the normals with vector nodes or something else that gives me smooth shaded normals for the fresnel effect?
Comment: How are you "Editing" the normals, then? I'm not understanding something about your setup.
Comment: with the normal edit modifier. the only one that is not collapsed in the modifier stack
Comment: Isn't that what the "Normal" output is? The one two spots up from "True Normal"?
Comment: no, these are just the edited normals
Comment: I understand the problem now, I've never looked at that modifier before. Sorry, I don't have a solution.
Answer: I hope there is a better way to do this, but here is a workaround I used:
I copied 'normal' normals to a uv layer via script. Two layers to be exact. While I could have compacted them into a single layer, it would have increased shader complexity
import bpy

ob = bpy.context.object

for loop in ob.data.loops :
    normal = ob.data.vertices[loop.vertex_index].normal
    ob.data.uv_layers["XY"].data[loop.index].uv = (normal.x, normal.y)
    ob.data.uv_layers["ZW"].data[loop.index].uv = (normal.z, 0)

Then in shaders I plug the combined value into fresnel normals input.
Here are sample results form left to right:

Default monkey with default fresnel
With normals edit and custom normals plugged to fresnel
With normals edit and default fresnel

The artefacts (sharp white areas) are due to lousy normal edit, which I bet you will not have in your model. Otherwise the normals carried over from UVs appear to be near identical to original smoothed normals
EDIT: As noted by Heinrich Tester, the normal from UV must also be transformed from object to world space before use
Comment: Nearly perfect, but the fresnel effect doesn't work correctly when you rotate the object. I fixed this by putting a vector transform node between combine XYZ and normalize, then set it to normal from object to world. Now everything works fine, thanks!

Smooth shading with nodes?


What are "feeder cells"?

Question: What exactly are "feeder cells"? A paper I'm reading says they harvested the cells and then plated them onto feeder cells. What is the purpose? Is in order to promote growth?
Answer:
Cultures of growth-arrested feeder cells have been used for years to promote cell proliferation, particularly with low-density inocula. Basically, feeder cells consist in a layer of cells unable to divide, which provides extracellular secretions to help another cell to proliferate.

From this paper's abstract:
Feeder Layer Cell Actions and Applications

What are "feeder cells"?


How Horoscopes (Jataka) are written?

Question: How do astrologers writes a Horoscope of new born child? Can they be accurate in determining one's life partner or destiny?
Comment: When Einstein gave the General Theory of Relativity, it is said that only 8 people in the world understood what he was saying. I believe the same goes here, astrology is a science but the number of good astrologers can be counted on your fingertips.
Answer: The astrological charts of a new-born baby are written taking the moment when the child takes its first breath (independent of its mother). The planetary positions at that moment determine the pre-destined portion of the child's life (prarabdha Karma that the child brings from its previous incarnations/births). Hence, the Natal horoscope (Jataka) will greatly shape the proceedings of the individual's course of life and will play a predominant role in influencing its will, determining the circumstances that the he/she will face and conditioning the abilities at different ages.
Having said that, the individual can use its free will to counteract the influences and, by virtue of blessing from higher souls, the individual can endure (and in certain occasions, overcome) the pre-destined fate.
Answering your second question, there is a curse on astrology that no human can have a accurate (100%) prediction on all aspects such as what, why, how, where, when and by whom (at the same time). However, with reasonable accuracy and precision, destiny can be deciphered (with decently accurately but limited precision). Life partner being a subset of destiny can also be predicted. Most predictions will be indicative and significantly reliable given that the astrologer is well learnt, the dashas and antardashas of the astrologer is reasonably favorable, has yogas that made him an astrologer with Vak Siddhi (capable of saying things that come true) and the querist has the bhagya to know the truth at that juncture of time.
Though all this looks complex by analysis, it is an experiential learning that will help have a better understanding.
Comment: Thanks for the answer. Answers on this site should be supported with reliable sources. Can you cite sources for statements ." Charts are written for time of first breath" and " Curse on Astrology"?
Comment: So, according to Science, Babies will air take for the first time when they cry. So, "should we use time when babies cry for the first time" for Astrological Charts?
Comment: @The destroyer:
Unfortunately i do not have a clear citation to your first question on source of the curse. If you are familiar with Mahabharatha, this example will be of some help.
Comment: Sahadeva was a very great astrologer who is also a student of Deva Guru Brihaspati himself. He could predict outcomes of the kurukshetra war much before hand and was capable enough to also prescribe muhurtas that could make Kauravas win. But, the curse has to play its role to make prarabdha karma come true.
Comment: With respect to your second question, the time the child takes its first breath is to be taken. Now whether the child cries, is on oxygen mask and breathing or anything else is left to the circumstance at birth. Under normal conditions, the instant it starts crying is to be taken.

How Horoscopes (Jataka) are written?


Sitecore Habitat with Glass Mapper

Question: Just wondering if I use glass mapper or any DI framwork then will I need to implement in each project separetly? otherwise  if I create a separate project for DI or Glassmapper and add the reference in each habitat project then i guess it will break the habitat rule which says keep the module separate.
Comment: With help/input from the guys from GlassMapper I looked into creating a sample version of [Habitat with glassmapper](https://github.com/muso31/Habitat-Glass.Mapper). The News feature has been updated so take a look at that as it will give you an idea.
Comment: @Muso I have converted your answer to a comment, because you did not provide any details about the solution itself. So your answer was a [**link-only answer**](http://meta.stackexchange.com/a/8259/183720), which we highly discourage. If you want, feel free to create a new answer that outlines the solution and includes details on how it actually works. Please see [**this thread**](http://meta.stackexchange.com/questions/7656/) for some tips on writing good answers.
Comment: @Muso I have reviewed your project but that doesn'tn seem to be right approach as you have added glass reference in one of the Feature projects (news). Glass project needs to be implemented in foundation layer and refers in feature layer. Also you are explicitly adding your mapping class in mapsConfigFactory but that should be a general statement to cover most of the required mapping (preferably using DI)
Answer: You can put it to the Foundation layer. Any project in any layer can have references to the Foundation layer. Also, a Foundation project can have references to another Foundation project, but you need to follow this rule:

Unlike the Feature layer, there is no strict convention on dependencies between modules in the foundation layer. This means that one Foundation layer module can depend on another Foundation layer module in the solution – as long as they rely on the basic principles on component architecture such as the Acyclic Dependencies Principle and the Stable Abstractions Principle:

Source:
Helix principles
Do not forget that Habitat is just an example of how Helix principles should be applied.
Comment: not really. you can use DI which you want and for sure you can use glass mapper or another Sitecore ORM :)
I think they do not use glass mapper or DI because they do not impose a technology stack. so you can get the habitat example and integrate any DI or ORM which you want.
Comment: Makes sense to me.Thanks. I understand Habitat is just an example but does this also suggest to not use glass mapper or DI and keep the modules least dependent on external resources?
Comment: Can you please also suggest that is it advisable to start a new project using example habitat project provided by sitecore and add new stauff (mainly feature projects) as per client requirement? or one should start with clean solution and only the stuff required by following the helix principle?
Comment: you are free to choose. you can start clean project and use the Habitat modules if you need it. Habitat contain collection of good approaches but for sure you do not need them all.
this is the main advantage of using modular architecture that you can take module from one solution and easily set up it to a new solution.

Sitecore Habitat with Glass Mapper


Needing to recover husband's bitcoin account

Question: My husband passed away a few weeks ago and he had a bitcoin account. Is there any way that I can recover that and transfer it?
Comment: Possible duplicate of [My husband died, I have lots of codes and words... help](https://bitcoin.stackexchange.com/questions/89841/my-husband-died-i-have-lots-of-codes-and-words-help)
Comment: Additionally, if you happen to find his wallet/stash **DO NOT** share the 12/24 word phrase, private keys, or wallet file with anyone online. Anyone with this information will be able to spend his coins (ie, rob you). Anyone legitimate that is offering help will not ask you for this information. I highly recommend moving slowly and being sure of what you are doing, before doing it. There should be no rush, best of luck.
Comment: I'm sorry to hear of your loss. It may be possible to recover your husband's BTC, but the answer will entirely depend on how and where you husband stored them: it may require you to locate a piece of paper with 12/24 words written on it, or find a hardware device that he stored them on, or to open a certain application on his computer or phone, or log in to a certain service online, etc. Try searching his email/computer/personal files for words like bitcoin, wallet, btc, blockchain, crypto, etc, to see if you can find any clues.
Comment: I have never posted on here so it is not a duplicate. I have nothing but a link on his browser that says bitcoin.
Comment: @ColleenWallace What does the link go to? How do you know he actually held bitcoin (or do you)?
Comment: Sorry for your loss. There are answers to a similar question here that can be relevant: https://bitcoin.stackexchange.com/questions/89841/my-husband-died-i-have-lots-of-codes-and-words-help/89898#89898
Answer: I'm sorry for your loss.
If your husband is keeping bitcoin at a big name bitcoin exchange, you may want to contact the exchange administrator to inquire about the procedure.
If the bitcoin is outside an exchange, then accessing it requires knowing a very long password or a very large number, possibly starting with "0x" (meaning hexadecimal). It would probably be written somewhere on paper, but may also be hidden in a password-protected file or stored in a special USB or other crypto device.
If you have reason to believe your husband may have significant money in this, you should really find a knowledgeable friend whom you trust to help you find the access credentials for the money. Unless you are pretty tech savy yourself, you should strongly consider immediately selling the bitcoin for "real money".
On the other hand, if you have no evidence that your husband had money in bitcoin (other than, as you said, "a link that said Bitcoin") you may want to understand that there are a lot of people with interest in Bitcoin who do not hold a meaningful amount of Bitcoin.
Lastly, as said already, do not trust anyone on the internet. Do not give anyone any passwords or any numbers you do not fully understand until you get help from a knowledgeable friend or have educated yourself very carefully. It is extremely easy to steal Bitcoin, it is nearly instantaneous, and it is almost completely outside of legal protections.
Answer: Your question caught my attention I would like to try and give you some answers. First of all, I want to say that I'm sorry for your loss. You ask if there is any chance for you to regain access to the bitcoin so that you can transfer them. In short, my answer would be yes, it is likely that you can - if you have some essential information. You don't mention in your question if you have found any wallet files, passwords, words, or other leads that can help you. But if you have any of these things there is still hope. If you can't find the wallet file but have access to the computer of your husband, it's likely they are on there and there is help to get to find them. If you are tech savvy yourself, it's possible for you to start the process from home. What would hold you back would be the processing power of your home PC, since they don't have the power to test many passwords at the same time, the process can be very long, longer than you can possibly wait.
If you know anything about the password, for example, - Password span (how many characters) - Password language - Any numbers or special characters used - Did your husband usually make passwords by combining words or how did he usually come up with them?
Every detail will narrow the possibilities and shorten the search time. Some of the free softwares out there that you could use are John the rippers or Hashcat. You can read up on them online. Recovering passwords is something I do for a living so that's why I know one or two things about it :)
Also, as some people above have already warned you, don't hand out any information about your bitcoin to strangers, bitcoin is unfortunately easy to steal if sensitive information gets in the wrong hands. Good luck!
// Isabella


Giving higher permission to flatpaks

Question: How I must give a higher permission to flatpaks? for example I can't send files with Telegram flatpak.
Answer: You can do this via the command line. The specific command you need is (it may need to be run as sudo):
flatpak override package_name_here --filesystem=path_here
If you have an odd path & it complains about an "unexpected filesystem suffix", just put the path part in quotes.
A more complete list of permissions commands is found here - http://docs.flatpak.org/en/latest/sandbox-permissions.html

Giving higher permission to flatpaks


Collect with symbolic exponents

Question: I need to collect a polynomial in a variable r. The exponents of r are possbily symbolic.
For example, the expression
Collect[r^(2 a) (1 + r^2) + (1 + a) r^2, r]

gives
r^(2 a) + r^2 (1 + a + r^(2 a))

while what I would like to have is
r^(2 a) + r^2 (1 + a) + r^(2+2 a)

Of course my expression is much more complicated, but this gives the idea of what happens.
Comment: What about Expand insted of Collect?
Comment: @FredSimons I want all the terms that are multiplied by the same power of r to stay together. Expand would not work in this case. I will change the example to make it clearer
Answer: Your example with some extra terms:
exp=r^(2 a)+r^2 (1+a+r^(2 a)) + r + a r;

Collect accepts patterns, so you can collect with respect to powers of r:
Collect[exp, r^_]
(* (1+a) r+(1+a) r^2+r^(2 a)+r^(2+2 a) *)

Collect with symbolic exponents


alt-shift toggles keymap when part of a shortcut

Question: I have two xkb layouts, and use Alt+Shift to toggle between them:
setxkbmap "fr,us" -option grp:alt_shift_toggle

However, when I press a shorcut which contains Alt+Shift, the shortcut isn't taken into account, and instead the layout switches. For example Alt+Shift+Left (which selects code to the matching closing paren in some editors), or Alt+Shift+% (which is search and replace in emacs, the % needing Shift on French keyboards).
This was not the case with XUbuntu 14.04 I think, but I switched to NixOs, and I now have this issue.
How can I configure setxkbmap so that it switches layouts only when Alt+Shift is not part of a shortcut, i.e. upon releasing the keys and only if there wasn't another key pressed at the same time?
Answer: This is a known limitation in xkb. sxhkd would be a better solution and gives you better control.
Add this to sxhkdrc:
Shift_L + Alt_L
    setxkbmap -query | grep -q 'fr' && setxkbmap us || setxkbmap fr,us
Shift_R + Alt_R
    setxkbmap -query | grep -q 'fr' && setxkbmap us || setxkbmap fr,us

Note that for some reason, alt must be pressed before shift to be detected by sxhkd.


Is 1. d4 Nf6 2. Nf3 e6 3. c4 d5 called Queen's Gambit Declined when there is no gambit offered, let alone declined?

Question: I understand that the opening 1. d4 d5 2. c4 e6 3. Nf3 Nf6  is called Queen's Gambit Declined. But how about 1. d4 Nf6 2. Nf3 e6 3. c4 d5? There is no gambit offered, let alone declined. Is it still called Queen's gambit declined?
Comment: In either variation, it's still not a true gambit.
Comment: @MikeJones, well, in the order 1. d4 d5, 2. c4. Black has the option to accept the gambit, though the choice may not be the best one.
Comment: The Queen's Gambit isn't a true gambit as black can't keep the pawn.  Other gambits trade the gambit pawn for another advantage.
Answer: Yes, it is still called the Queen's Gambit Declined. That's just the name of the system, regardless of the move order used to reach it. However, it is not the QGD before Black chooses to push 3...d5.
Answer: They reach the same position, so they have the same name. It wouldn't make sense to call the same position differently depending on the moves that lead to it. 1.f4 e5 2.e4 is a King's gambit, not a declined From's gambit. 1.e4 c6 2.d4 d5 3.cxd5 exd5 4.c4 Nf6 5.Nc3 e6 6.Nf3 is a Tarrasch Defence despite having started as a Caro-Kann
Answer: This is a transposition, you have to think about the pawn structure instead on focusing on the concrete order, there are thousands of different ways of getting to the same (or quite similar) positions


64bit vs 32bit on mobile devices with 2gb ram - is there any sense?

Question: Today I took part in an interesting discussion. Someone said that's great that Apple goes 64bit with their iPhone 5S. Of course I mentioned about no need for 64bits paired with 2 gigs of RAM, but then I started to wonder - is there anything good with 64bit in this case, except for benefits of "future compatibility"? Larger instructions? Any kind of optimalization?
Answer: Since the iPhone doesn't use an x86 processor, almost everything you know about 64-bit versus 32-bit will not apply. For example, on x86 processors, more general purpose registers are available in 64-bit mode. This provides a performance boost in 64-bit mode. That doesn't apply to non-x86 processors.
64-bit operation tends to provide benefits to software that handles "bulk data". This generally includes things like encryption, compression, and image processing. Other types of programming don't significantly benefit because they seldom deal with values that occupy more than 32-bits. Also, more memory bandwidth is required by 64-bit code because all pointers are twice as large and this can cause some performance loss.
However, there is one big advantage of 64-bit code over 32-bit code -- virtual memory need not be treated as a scarce resource. This can have all kinds of benefits both for performance, ease of development, reliability, maintainability, and so on. For example, if you're manipulating a large database file, you can memory-map the entire file and access it just like an array. This can eliminate a lot of slow, complex, error-prone code to memory map sections of the file or alternate seeks with data operations.
Similarly, libraries can have fixed virtual addresses. This can improve code sharing and result in memory being used more effectively. It can minimize relocation, which can result in faster code startup.
To be honest, you would have to know a lot about the internals of how the device operates, both in software and in hardware, to usefully opine on whether a change from a 32-bit platform to a 64-bit platform will provide significant benefits.
Answer: No. Actually it hurts - as 64 bit programs are larger. And if you are so space constrained....
Likely a strategiy move for long term compatiblity assuming that the next generation will maybe have more than 4gb.
Answer: I'm thinking I'll regret this answer... here goes:
Yes, the "sense" is marketing. 64 bit is a fantastic keyword! Bigger, better, moar, and 99.7% of the iPhone buying public will think this.
Rules and values of big business:
1- Marketing/brand image
2- Marketing/brand image
3- Accounting
4- Lawyers
5- Engineering
I would have +1d the question because I almost always as a rule will +1 questions I answer; however:

is there anything good with 64bit in this case, except for benefits of
  "future compatibility"

There is no future compatibility with mobile devices.
Comment: By "future compatibility" i mean apps and perhaps no need to run them in 32bit mode when, let's say, iOS 10 and iPhone 8 goes public. I'm pretty newbe when it comes to architecture, sorry if I made any mistake.


"Jumpy" horror film sounds/score

Question: Morning,
My girlfriend and I finished watching the horror film Mama the other day. Obviously, one of the key devices used to make the viewer 'scared' is via the use of sound and score to make us 'jump' in certain parts.
We've all seen it and experienced it in countless films before where a loud noise or orchestral sting accompanies a scary moment. My girlfriend asked me the question after, as to where did this use of sound/score come from? Is it just now a 'convention' that is used in horror film now, and was there a particular film that first used this to effect and has been copied since? Just why is it so successful and making us feel jumpy, and on edge? Does it just boil down to an evolutionary thing where we are programmed to react to loud/sudden noises, and why are certain instruments and frequencies more effective at making us feel this way than others?
Any thoughts would be very interesting to hear... ;)
Answer: The BBC did a cool documentary on this a while back which you can find here. They delve into questions of context, and well as cultural triggers.
Edit: This just appeared in my RSS... Specifically talking about game audio, but the science is the same.

"Jumpy" horror film sounds/score


Anyone any good reference about the variables available in the view template?

Question: Tried to print variables in view template, but the print-out is huge,deep-nested and recursive... crazy thing... Just can't drill down to the rendered_fields array, which seems to be just what I need. Is there any comprehendable reference anywhere?
Answer: What I usually do when I need to inspect a views variable, that often can be as complex as you describe is to use dpm. Dpm can't always show all of the items since the information is repeated. But then you can dpm the specific parts you need.
So you often start doing dpm($view); but end up using dpm($view->displays...); to get what you need. Using a reference might be a bit overkill since the view varisble is dymanic, but after doing it a while you start figuring out where you can find stuff. The names is pretty selfexplanatory.
Comment: If you aren't logged in as a user with appropriate permissions, dpm() doesn't display.
Comment: That sounds as a solution... but when I do dpm($view); nothing gets printed out?.. Any special treatment needed?
Comment: Found out that dpm uses kprint_r() so I just used it directly - awesome! Still not sure why dpm didn't work though... and I still wouldn't mind to see a good reference about what all these fields are for :|
Comment: I thought of this, but I thought I was logged in as admin. Ok I will look into this, thanks.
Answer: A little underground byt you have
<?php
dpm(get_defined_vars());
?>

Answer: There is a row template that can be found in the Views theme section. It iterates through each field and then wraps it in markup. Another way to do it is to test if a field is empty then print it. Here is an example from a template I just created.
  <?php if (!empty($fields['field_dicussion_category']->content)): ?>

Category: <?php print $fields['field_dicussion_category']->content ?>

  <?php endif; ?>

What you can do is a dsm($fields) which will show you the available options.
I don't know too much about the Eclipse IDE or ClientXDebug but I use PhpED to work with code in Drupal. It only costs a couple hundred bucks and is completely worth it. I can put a breakpoint in any part of the code and the IDE will stop the page load and show all the variables. Better yet I can step through and see how the variables change.


Logistic regression threshold value

Question: How can i set the threshold value for the target variable. For example if a target variable is chance_of_admit and it has values from 0 to 1, how can I pick a value and so that I can convert it to 0's and 1's to perform logistic regression
Comment: Hi, I would say see how the distribution of the the target variable is and if its normal then probably .t threshold will be fine otherwise if it is skewed you should defined lower or higher the threshold based on skewness..
Comment: @Cini09 It is negative skew . So how I must proceed
Comment: @Cini09 do u have a solution for this
Comment: It depends but you can try to increase the threshold to like 65-70 and see how dies it cover your majority of sample.
Comment: And create a different column and compare with the original one or with another column which has .50 threshold. Doing so will let you know if you have covered enough sample in class 1.  And then you can proceed with the modelling
Comment: @Cini09 thanks for the solution
Comment: Please letme know if you want me to elaborate more on this, I can explain with an example.
Comment: @Cini09 if u can please explain
Answer: So there two ways of doing this, IMHO,

By creating a well balanced target variable by choosing the right threshold. As I suggested in the comments above. In doing so we are simply taking care of values which should be treated as positive which would otherwise become negative if we take lower threshold.
By using the mean threshold and that will generate imbalanced target variable and when you perform the modelling, you can see the ROC and PRC curves and decide the threshold based on that. But keep in mind, it also depends what kind of problem you are solving.
Answer: Usually, the threshold is 0.5. So when you make a prediction from a binary classification model, the prediction will be a probability, and 0.5 is the threshold for assigning classes based on this (estimated) probability.
However, in your case, the dependent variable $y$ is something like a (pseudo) probability, as far as I understand. So you could also check if predicting this value, using a regression approach, would be an option.
You could look into beta regression in this case: https://stats.stackexchange.com/a/29042/224077

Logistic regression threshold value


Contact Us thank you message

Question: we currently have a contact us page that allows visitors to send an email to us through it, would it be a good idea to also send an email to the visitor thanking him for the message to let him know it was sent?
Answer: As long as you provide confirmation on-page as soon as they have submitted the form, then you don't need to send the email. Typically, confirmation emails may infer that a ticket of some sort has been opened. From this email, the user can see a ticket # and can respond.
Answer: As far as you showing an alert with a thank you message on submit of form no need to send an email.
Reasons:
1- Email gets ignored
2- I personally don't like to receive an email for a thank you message
3- you need to develop a mail template which can increase time and cost.
You can send a reply email based on the query submitted by the client and in that you can add a Thank you message.
Answer: A follow up email may be considered spam, but as others have said, you should provide feedback as to the state of the action within your site.
Some suggestions for the feedback:

The feedback should inform the user what happened (e.g. an email was sent to us, and probably thank them for their time/effort)
The feedback should set the users expectation (e.g. you will receive a reply within 24 hours)
The feedback should let to user what to do next (e.g. Go back to their task, display a relevant CTA etc)

There's probably more, but those would be a good start.
Answer: In-page feedback and thank you message is absolutely necessary.
Regarding a possible email, rather than a thank you note, you could let the user decide if they want to receive a copy of their message at their email address. It's both a confirmation that their message has been sent and a copy for their own record that they might find useful (depending on the type of website and message they send).

Contact Us thank you message