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12:07 AM
:/ I'd submit for Sophie Germain by the scoring confuses me
 
12:30 AM
@Sp3000 It's still odd, but it's soooo much better than how the original had it.
 
o_O
 
12:46 AM
o/
 
I just saw a colorful ad for PPCG on the sidebar of cstheory.se. Are these this new? Have I been living under an adblock rock?
 
I wish more people would answer my question. There's a bounty and everything.
 
@Calvin'sHobbies they've been around forever
for you essentially forever :P
 
...woah
 
1:02 AM
we're also on mathematica.SE these days
 
1:29 AM
Anyone willing to give some feedback on this upcoming challenge? I've posted it to the sandbox, but haven't got any feedback. I want to post it very soon, but I also want it to be complete.
0
A: Sandbox for Proposed Challenges

DJ McMayhem Lets play a game of Meta tic-tac-toe! This is a king-of-the-hill tournament of Meta tic-tac-toe. The rules of Meta tic-tac-toe are as follows: All of the regular rules of tic-tac-toe apply. There are nine boards arranged to make one master board. Like so: 0|1|2 || 0|1|2 || 0|1|2 ----- || --...

 
Hmm not sure if the game is complex enough, but it's hard to say without implementing anything
 
@Calvin'sHobbies Adblock is the best.
2
Except it would be cool to see a PPCG ad somewhere.
Seeing my endorsement for Adblock on the side after being starred almost feels like an ad for Adblock. Oh the irony.
 
@AlexA. I have adblock disabled for SE and SO.
 
@AlexA. They should totally start putting up adblock ads.
 
@TheNumberOne Why? Are there even ads there? Haha I guess I wouldn't know.
@DJMcMayhem They would get blocked by Adblock.
 
1:42 AM
@AlexA. But it's not good for the thousands of people who produce information and entertainment for free online, and rely on ads to make a living. I feel guilty using AdBlock.
 
@Calvin'sHobbies I just... try not to think about it. u_u
 
@Calvin'sHobbies Unless you accidentally use yahoo answers.
 
Oh! @Calvin'sHobbies, do you get YouTube ad revenue?
@TheNumberOne What an unfortunate accident that would be.
 
Sssshhhh! A mod just entered!
 
Another one (the same one) entered.
 
1:46 AM
Everybody hide!
 
Uh oh, he's gonna scroll up the transcript and see where Alex was talking smack about him ;)
 
Wha chu talkin bout, Willis?
 
Well now that there's actually people in here, does anyone else have thoughts on my challenge?
 
I have no thoughts in general.
Little known fact about me: I'm actually the result of a PPCG challenge.
Beep boop.
 
Which challenge?
 
1:49 AM
@AlexA. No, I was trying to but there was some sign-up bottleneck and then I stopped updating my channel anyway (though I will someday get back to it). I do make a few cents a day from an Android App I made.
 
@DJMcMayhem Frankenstein
 
@DJMcMayhem I think about the same as last time. It sounds good, except I have a fear it's too solvable (no proof of that, just seems that way).
Worst case is you post it and someone answers with something optimal and it just breaks down.
 
Which will advance the field of game theory!
So it's really a win-win
=p
 
@DJMcMayhem This one. That's my DNA everyone coded.
 
That sounds like the best sort of attitude to have about it :D
 
1:52 AM
@Calvin'sHobbies Whoa. That's really cool!! I (almost) wish I had an Android phone so I could try it out. You are one talented fellow.
 
@AlexA. So you're entire existence can summed up in just 50 bytes?
 
...Yes.
The fewer the better, really. After all, I am code golf.
 
Now I am become code-golf, the destroyer of bytes.
 
As long as you're not the destroyer of bits.
 
I AM CAN HAS GOLF PL0X
 
1:54 AM
@AlexA. 20469...less than 15 bits or 2 bytes
That's enough identification here
 
@Calvin'sHobbies I don't understand
 
@Calvin'sHobbies Ah, okay. Now I get it.
In other news, @Calvin'sHobbies, you should port your stuff to iOS.
 
@AlexA. Don't own any apple stuff
And testing in emulators is not quite the same
 
You don't have to own any Apple products (I don't think) but it makes it easier. But you have to pay a ton of money to actually have your app listed on the App Store because it requires being a registered Apple developer.
 
2:00 AM
That's true as well, I remember researching all of that
Apple is persnickety
 
That's one word for them, yes. ;)
And yet here I am typing on a Mac.
 
@AlexA. Same here!
 
I want to like Linux but I have yet to find a distro that really appeals to me. I don't like Windows >7. The only OS I've found that really appeals to me is Mac OS X.
@DJMcMayhem NICE. Virtual high five.
That's not to say I'm against Linux or Windows, just personal preference.
@Calvin'sHobbies Interestingly, on a Mac, when you develop for iOS, you run an iOS emulator to test your code. Haha. So it's emulation no matter what.
 
I might not have so much Mac prejudice if I didn't have to suffer through 12 years of public school with single button mice.
 
I understand your plight.
(All of my schools that had computers available for student use had Windows though.)
NOBODY UPVOTE @DJMcMayhem. REP LEVEL AT 666. So metal. \m/
 
2:12 AM
haha yeah!
 
Sorry bro, this is the rep level you'll be at for all eternity.
 
When I used to work in fast food, there was a very specific combo that people sometimes got that would work out to exactly $6.66. It was funny to see people freak out.
One guy actually demanded that I change his order because he didn't want to check out with that price.
 
...Whoa.
 
671. It's gone.
 
Oh shucks.
Wow, two of my messages today have been starred and I'm mentioned in a starred message from Optimizer. I don't know if I can handle the fame.
 
2:27 AM
The 4 most recent questions each have a score of 4 (in absolute value)
 
Woah, how do you post a gif like that?
 
Add a ! before the image URL
 
2:38 AM
So are you no longer in food service, @DJMcMayhem? Perhaps programming for a living?
 
No, and no.
 
What do you do now?
 
I'm 17, programming for a hobby.
Although, I do have an internship programming with an electrical engineering company.
 
Cool, congrats! So are you aiming toward a career in programming?
 
Yeah. I've been coding obsessively for about 2 years now, and I enjoy it a lot.
 
2:41 AM
Nice. Favorite language or favorite kind of problems to work on?
 
Although, the project that I'm going to be working in is a little bit overwhelming, given that the largest program I've ever written is 1300 lines.
hmm, I really like python. Especially with pygame. That's what originally got me into coding.
As you can probably tell from my avatar.
 
It's an internship, so they won't expect you to come in knowing exactly what to do. You'll get training and it sounds like you'll have no trouble at all getting up to speed.
So Python got you into coding. What got you started on PPCG?
 
What about you? Are you coding for a living?
 
I am. I did a BS in math and I'm working on a master's in statistics part time, and in the meantime I program in an awful language called SAS.
 
Side-Angle-Side triangle?
 
2:45 AM
Uh... nope?
Statistical Analysis System. Used to be an acronym, now it's just the name.
 
Sorry, my heads in trigonometry world.
I'm not really sure what got me into pcg. I think I just saw a bunch of links to it on the SO sidebar. Then I got curious and clicked on them.
 
Were they all of @Calvin'sHobbies' challenges in the Hot Questions list? :)
 
I don't even remember.
 
Well, regardless, we're glad you're here! (I assume I speak for everyone on that.)
 
Thanks, I'm glad to be here! I really like writing challenges, but I have a hard time making good answers.
Probably because I don't know CJam.
 
2:51 AM
You should learn Pyth.
 
Java
 
@isaacg Says the creator of Pyth. ;)
 
Haha, shameless self-promotion.
@isaacg Here's a question for you, as the BDFL of pyth, can you import a regular python module into a pyth script?
 
@DJMcMayhem CJam isn't necessary to make a good answer. It's the approach that makes it good, and that will be reflected in up/down votes. Code size just makes it competitive to get the green check. I've never won a code golf challenge but I like to participate anyway using the languages I know.
 
Java provides the best challenges to golfing.
 
2:56 AM
@DJMcMayhem Sure, though only on the command line compiler.
 
Eh, I take it back.
 
@DJMcMayhem Here's an example Pyth program: $import time$pb$time.time()
Prints the current system time.
 
Okay, any good recommendations for how to learn it?
 
@DJMcMayhem: Here's an example Lisp program: (((())(+ x)-(()-))d)()()+))(())1)))()())(())))
 
^ That's what I want to learn.
 
2:58 AM
@AlexA. That's terrifying.
 
Is there any common keyboard layout that does not have 1234567890 running along the top?
 
@Calvin'sHobbies APL keyboard
 
@Calvin'sHobbies TI-83+ SE calculator keyboard.
 
@DJMcMayhem It's a joke ;)
Although it's not too different from Parenthetical.
 
@TheNumberOne I guess I mean PC keyboard
 
2:59 AM
@AlexA. It reminds me of lambda calculas.
 
@DJMcMayhem Check out this: pyth.readthedocs.org/en/latest
 
@Calvin'sHobbies A lot of ATMs run (or used to) Windows XP.
 
A introduction to Pyth, followed by a partial language specification.
 
@TheNumberOne Not too surprising. Quoth Wikipedia, "Lisp was originally created as a practical mathematical notation for computer programs, influenced by the notation of Alonzo Church's lambda calculus."
@Calvin'sHobbies I got it! The French keyboard. The top row is &é"'(§è!çà. You have to hold shift to get the numbers.
AZERTY /əˈzɜrti/ is a specific layout for the characters of the Latin alphabet on typewriter keys and computer keyboards. The layout takes its name from the first six letters to appear on the first row of alphabetical keys. Like the German QWERTZ layout, it is modelled on the English QWERTY layout. It is used by most French speakers based in Europe, though France and Belgium each have their own national variations on the layout. Luxembourg and Switzerland use the Swiss QWERTZ keyboard. Most of the residents of Quebec, the mainly French-speaking province of Canada, use a QWERTY keyboard that has...
 
3:17 AM
More random questions: what would happen if a football ball sized portion of the solar core instantly appeared on Earth, say in the middle of a football field?
 
Boom
It depends on whether a game is happening at the same time ;)
 
@Calvin'sHobbies Everything would be instantly incinerated. Everything.
 
@Calvin'sHobbies That's basically what a thermonuclear bomb is.
 
@AlexA. I don't think anything would happen (to the sun) if a tiny piece of the sun disappeared. The sun would practically have 0 side effects.
 
@TheNumberOne: That's true. I mean the Earth's surface.
 
3:23 AM
I was really thinking about that the other day. I know it's hot and dense, but would the damage really be on a planet rending scale?
 
The sun is plasma, superheated gas. It's so hot that the rock and everything would sublimate. That is, it would go instantly from solid to gas.
 
@Calvin'sHobbies That's what I used to think... until I learned how little damage the earth would do if it turned into energy.
 
Not the entire Earth. Just within some radius.
 
I've found I'm not the first to wonder.
 
The pressure a thermonuclear bomb uses to cause fusion is much higher than the pressure of the suns core, so the result would be similar to a few of those bombs - everyone within a few miles would be dead.
 
3:32 AM
I used to work with Tokamaks! :D
They magnetically confine plasmas.
Just noticed that using ":D" doesn't quite fit the mood set by Isaac's comment about everyone being dead.
 
In other news, gs2 is giving super short hexdump answers that weird me out.
 
@Calvin'sHobbies I just checked FIFA's rules of the game, but unfortunately they do not seem to have a section on what happens to the match if a football-sized fireball appeared
 
Haha
I assume Calvin meant American football. The ball is a little smaller, so less destruction. I'm sure the NFL has prepared for such an event.
 
@Sp3000 I foresee a lawsuit :P
@AlexA. No, I meant soccer
 
@Calvin'sHobbies Classic Dvorak also does not use the standard ANSI Dvorak number layout.
 
3:43 AM
@Calvin'sHobbies ...Then why did you say "football"? ;)
 
Because it's called football too
 
^ Every where other than USA
 
Football is the proper name. That's why the association is called FIFA. ;-)
Soccer is short for "association football".
 
Well apparently the referee is not liable if they choose to cancel a match due to whether, but upon further reading "If an extra ball enters the field of play during the match, the referee must stop the match only if it interferes with play."
*weather
 
@Sp3000 You can edit a recent message (posted in the last 2 minutes) by pressing up.
 
3:46 AM
I'm on mobile :/
 
I know these things about football, soccer, etc. I was joking. Doesn't always translate well to plain text.
 
@Sp3000 Yeah, the mobile chat site is less full-featured than the desktop chat site. :-(
I actually use the desktop chat site on my phone for that reason.
 
The sidebar renders a bit weirdly on mine, unfortunately :/
 
Yeah, I ignore that.
One of the things we want to work on (but not very high on the priority list as far as I know) is to create an API for the chat system, so that a native mobile app can be written for it.
But that is a lot of work, so I'm not holding my breath for it.
 
That would be super cool though.
 
3:51 AM
Everybody in the company agrees. :-)
We use our chat system for our internal communications, which means we all use this system more than most Stack Exchange users. ;-)
 
In that case, I'm actually surprised it's not higher on the priority list.
 
That's because we have a number of other projects that are even more important. :-) Nobody is saying that the chat API is unimportant at all.
 
Oh I know. But what could possibly be more important?!
 
Graduating
9
 
3:54 AM
@Calvin'sHobbies But didn't @Geobits say it happens in a couple weeks? :P
 
4:24 AM
0
A: Sandbox for Proposed Challenges

YpnypnWhat date is that again? code-golf On my website, users enter their date of birth in the style xx.xx.xx - three two-digit numbers separated by dots. Unfortunately, I forgot to tell the users exactly which format to use. All I know is that one section is used for the month, one for the date, and ...

 
 
4 hours later…
8:41 AM
this order 40 sticks is over tagged
combinatronic, sequence, permutation
all three are not required
 
 
1 hour later…
10:11 AM
@Optimizer I believe you removed the wrong one
sequence seems weird, but permutations is definitely applicable
 
feel free to change.
 
done
that problem seems hard
 
I have a basic idea.
but doesnt combin... covers permutations ?
 
I have no intuition for it, except that 40 is always visible for both and 39 is necessarily visible for one of them. but then you need to pick any 8 others for the 39 side, and 7 others for the 39-free side and find all the permutations where the remaining numbers are sandwiched between two larger ones.
@Optimizer so? let's just tag it then.
I don't see a problem with having tags of different granularity on a question
 
hi all
 
10:16 AM
@MartinBüttner think of it has a generalized case, not just for 40
 
@Optimizer the same argument works for any numbers
but it doesn't really provide an efficient algorithm
 
efficient what ?
cough cough
 
well in that case, just check all permutations and count the valid ones
but I agree with Sp3000's comment that the challenge needs a time limit
has anyone played the mobile game Linken? I think it would make a good challenge
@Geobits ^ it seems like your kind of puzzle
 
anyone feel like talking through some non-codegolf related math & algorithms? :D
 
@sirpercival woo!
 
10:33 AM
:D
ok so
i'm working on a 4D tic tac toe app
the app is currently playable, but the AI sucks
so at the moment i'm thinking about tesseract symmetry w/r/t precomputing configurations
so, let's start with this. my 5x5x5x5 board has 625 spaces -> a maximum of 313 moves for X and 312 for O. given that a hypercube has 348-fold symmetry, how many possible unique configurations are there?
is it just 625!/348?
i should say, a 4-hypercube
also, i mean specifically full-board configurations
 
So you always play to a full board even if a winning configuration is reached early?
 
well, no
i figured it would be easier to math "how many full board configurations there are" before we started getting into "how many unique valid games are there"
 
So ideally you want to know the number of unique configurations that do not contain a winning condition?
Ah OK
Then it's the way of arranging 312 pieces in 625 spaces less symmetrical duplicates?
 
i'm considering whether there's a way to decompose paths to unique games in a storage-efficient way
 
625!/(312!313!)
 
10:45 AM
yes, that's a great way to put it
@trichoplax does that account for symmetry?
 
Nope
But it does mean you have a much smaller starting space than you expected
(but still very large)
 
ok but we can probably just divide that by 384 right?
 
We need to know what you mean by 348-fold symmetry
Do you mean 348 different symmetries?
 
yes, a tesseract has 348 reflectional and rotational symmetries
 
So each of the reflections gives one reduction (since there are 2 possibilities) but some of the rotations will allow removing more than 2, right?
 
10:48 AM
hm, why?
(this is my first real foray into this kind of math, btw... you'll have to walk me through it a bit i think lol)
 
If there is a 4-fold rotational symmetry (such as a line through the centre of opposite faces) then there will be 4 different arrangements that are all rotations of each other.
Think of the simple case of just a square in 2d
You can rotate it 90 degrees 4 times before you get back to where you started
 
right, but each rotation only reduces by 1, doesn't it?
 
The factorial approach includes all 4 possible rotations
If you only want to count them as 1 if they can be reached by rotation, then the factorial approach will give you almost 4 times as many as you need
 
ahhhh i see
 
Bear in mind that not all configurations can be reduced for rotational symmetry though.
Example:
 
10:52 AM
but you're still dividing by the number of possible rotations
 
X . X
. X .
X . X
In this arrangement you can't get to another arrangement by rotation
turning 90 degrees just gives you the same arrangement again
 
sorry i'm on the bus and the internet is crappy
 
No problem :)
My point earlier was that each rotation can reduce the total more than once
 
ah, ok. so the number of possibilities is reduced by a MAXIMUM of n_symmetry
 
So if you have 2 4-fold symmetries, you could have roughly an 8th of the arrangements
I don't know the terminology, so what I need to know is what does that number 348 mean? Is it the number of different symmetries, some of which may have more than 2 arrangements? Or is it the total number you can reduce by?
In a square, you have 4 different lines of reflectional symmetry
And 1 point of 4-fold rotational symmetry
 
10:56 AM
a square in equivalent notation is 8
In mathematics, a hyperoctahedral group is an important type of group that can be realized as the group of symmetries of a hypercube or of a cross-polytope. It was named by Alfred Young in 1930. Groups of this type are identified by a parameter n, the dimension of the hypercube. As a Coxeter group it is of type Bn = Cn, and as a Weyl group it is associated to the orthogonal groups in odd dimensions. As a wreath product it is where is the symmetric group of degree n. As a permutation group, the group is the signed symmetric group of permutations π either of the set { −n, −n + 1, ..., −1, 1, 2...
 
Ah I see - so it does include the number of ways for each type
 
yes
 
And what about switching the positions of O and X? Do the following two count as separate arrangements for your purposes?
X . O
. . .
. . .

O . X
. . .
. . .
 
no they don't - i'm tracking them as 1 and -1 so that i can just negate the position
 
So you can almost halve the number of arrangements
 
10:59 AM
yyyyyes i believe so
 
(Not quite halve, because there is one arrangement that isn't changed by switching the 1 and -1s)
. . .
. . .
. . .
 
right
lol
 
Now, about dividing by 348. You can do a little more than that
If you had one reflectional symmetry, you could divide the total number of arrangements by 2 (almost, but let's put that aside for now)
 
right
 
If you had 2 reflectional symmetries you could divide by 2 for the first and 2 for the second, so 4 overall
If you had 3 reflectional symmetries you could divide by 2 3 times in a row, so 8 overall
 
11:01 AM
huhhhh ok
so is it dividing by 2^348?
wait no
 
That's what I'm thinking
 
rotational =/= reflectional though
there are 192 reflectional symmetries
 
Of course there will be a lot of exceptions so it won't be that much, but still a lot more than just dividing by 348
 
you can't divide by 2 for each rotational symmetry, can you?
 
For each m-fold rotational symmetry you can divide by m
(roughly)
So if you have 3 lots of 8-fold symmetry you can divide by 8, then divide by 8, then divide by 8 again
 
11:04 AM
are all rotational symmetries of an n-cube 4-fold?
 
I doubt it
 
or are they 2^n fold?
i think they're 2^n
 
Think of the cube case
A line through the centre of opposite faces gives 4-fold symmetry, and there are 3 of those
 
riiiiight ok. so
 
A line through the centre of opposite edges give 2-fold symmetry, and there are 6? of those
A line through opposite vertices gives 4-fold symmetry, and there are 4 of those
 
11:07 AM
i think there are fewer than 6 edge-symmetries
 
So I'm guessing a tesseract has all of those plus an extra type for the extra dimension
 
there might only be 2. you can generate the rest from face-symmetries
yeah, from cell-center to cell-center
there are 8 cells
 
There are 12 edges for the cube case, 2 of which are shared in each line, so only 6 lines
Yeah there are probably lots of reductions I can't visualise. If you try at different times of day there are people in here who really know about symmetries
 
hm. i'm trying to figure out if any of them are degenerate
 
I'm just guessing from trying to visualise it...
 
11:09 AM
hahaha me too!
 
i wonder if there's a closed-form solution to this kind of analysis, that we could generalize to higher dimensions: se16.info/hgb/tictactoe.htm
i doubt it
:(
 
My guess is that it's easier than we're making it, but still hard
 
here's an important question: how many winning lines are there?
 
How many pieces to win?
3 in a row? 5 in a row?
 
11:14 AM
i don't brute force the solution check, so i didn't actually calculate it
 
If it's 5 in a row to win, then all winning lines are corner to corner
 
each individual 5x5 square has 12 winning lines...
 
I imagine a tesseract has 16 "corners" / vertices
Each one can form a winning line to any of the others, so that's 16 * 15 winning lines
Then divide by two because A to B is the same line as B to A
So 120 winning rows
 
sec
 
wow, the question I asked in movies.se yesterday has only 16 views.
Graduation is magical
 
11:22 AM
ok so let's start with 2D, NxN. there are 2N + 2 lines - N for opposite edges, x2 for each direction, +2 for opposite vertices
in 3D, NxNxN
so generalizing, if you have a N^D board, you have: DN^(D-1) 1-dimensional wins (i.e., only one coordinate changing)
oh, i guess i'm not taking symmetry into account
hm
well let's ignore symmetry for a moment
 
I wasn't taking symmetry into account either
 
in 3D, you have 3N^2 1-d wins
 
In N-D, you have 2^N vertices so (2^N)(2^N - 1) lines, each of which has 2 directions, so divide by 2
So (2^(N-1))((2^N)-1)
 
with or without symmetry?
 
That only counts each line once (A to B and B to A are just 1 line)
 
11:28 AM
yeah that's fine
 
But you can still reduce by the symmetries of the board, depending on what you need it for
 
i'm brute forcing 3D to test my generalization
 
Depends what other pieces are on the board
Reducing for symmetry you only have N ways of winning in N-D
 
there are 18 2D wins in a 3x3x3 board, which is 2 per cross-section and N^2 cross sections
 
Ah - then my formula is wrong - I was only counting vertex to vertex - forgot you can go edge to edge from somewhere in the middle of the edge.
 
11:43 AM
my stats are so weird. 1 day 30 upvotes, next - 0
 
-0 votes. Wow
 
yeah, so weird, right ?
 
Does that mean someone retracted 0 upvotes, or made 0 downvotes?
 
someone retracted 0 downvotes
 
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