The Nineteenth Byte

Lembik

12:00

v. interesting!

can I add these to the question?

the n/2 aspect is surprising!

in fact very surprising indeed

looking at your code they are optimal, right?

Mitch Schwartz

yeah i checked all possibilities, without loss of generality (we can fix the first element as 1, and the second element as 1 as well)

Lembik

why can you fix the first two?

Mitch Schwartz

negating the matrix doesn't change the dot products

Lembik

I can see why you can fix the first one

but really the first two?

Mitch Schwartz

and there must be two of the same element adjacent in the first row, so you can always rotate to get them at the beginning

Lembik

12:04

I would need to implement a completely brute force solution to check :)

but I trust you

Mitch Schwartz

if you alternate 1, -1, 1, -1, 1, -1 you can't get above m=1

Lembik

oh I see what you mean!

I feel you have understand this problem very well!

so could the answer just be n/2?

seems odd this isn't mentioned in the literature if so :)

oh.. 14?

what do you get for n = 14?

or n = 10?

Mitch Schwartz

so consider a1, a2, ..., an

sec

i'm just trying to see a simple way to explain the parity argument

for (a1,a2), (a2,a3), ... (a{n-1},an), (an,a1)

in order for m >= 2 we need exactly half of them to be same sign

but (an,a1) is determined by the ones before it

so for (a1,a2), ..., (a{n-1},an), you'll have (same sign, different sign) = (n/2, n/2-1) or (n/2-1, n/2)

Sp3000

@BetaDecay What's this about? (Probably me using a conversational tone)

Mitch Schwartz

essentially, for n = 4k, (an,a1) will be the right value, and for n = 4k + 2 it won't be

Lembik

12:17

@MitchSchwartz do you mean m>=n/2 ?

Mitch Schwartz

@Lembik no

Lembik

@MitchSchwartz there can't be a simple argument as this has been an open problem for years

oh ok.. sorry

I am wondering why you get m = n/2 so much

what do you get for n = 6?

Mitch Schwartz

oh ok, simple explanation: for n = 4k + 2, you would need an odd number of the pairs in { (a1,a2), (a2,a3), ... (a{n-1},an), (an,a1) } to have elements with different sign, but that's impossible because it would imply that a1 = -a1

@Lembik those are all m=1, that's what i've been saying multiple times

Mitch Schwartz

12:35

there aren't too many matrices that reach the record for each of these small n; i'll print them all out and look for a pattern

Lembik

@MitchSchwartz oh yes you did.. sorry I was distracted

it would definitely be amazing if the answer is either 1 or n/2 !

Mitch Schwartz

well i'm not seeing a nice pattern that would allow you to construct a matrix with m = n/2 for arbitrary n = 4k, it would be cool if someone found one

or not necessarily a pattern, any way to generate them ofc

that is not too slow

orlp

13:50

@Lembik I'm a bit confused by orthogonality

could you help me?

why are the vectors [-1, -1] and [1, 1] orthogonal?

their dot product is not 0, so supposedly they are

but they lie on one line, no?

Lembik

@orlp they need to be at right angles

but they point in the same direction

orlp

oh wait I'm stupid

if the dot product is 0 they're orthogonal

Lembik

[-1,1] and [1,1] are at right angles

orlp

not nonzero

Lembik

yes :)

I had another version of the problem to minimize the maximum dot product between rows :)

maybe next time

Shebang

13:56

This looks like fun :)

Mitch Schwartz

i'm finding that the second half is often the negation of the first half except for a single reversal, in rows that reach max

or, a single non-reversal, if that's clearer

so for example with n = 24, the first one found was 110000001011001111010100, and the second half of that is almost the bitwise not of the first in this representation

Lembik

@Shebang what does?

Shebang

Your question!

Lembik

@Shebang great! :)

Shebang

If I get enough time today I will try it out, but I'm getting ready to move tomorrow :P

Lembik

14:08

good luck!

Geobits

Tomorrow gets moved every day. What's so special about this time?

Mitch Schwartz

i'll try a heuristic and see how it goes

Lembik

@MitchSchwartz good plan!

orlp

is it correct that there is no partial circulant matrix for N=6 that even has two rows?

Mitch Schwartz

yeah, i wrote about that above

orlp

14:13

oh

ok

is this true in general for 4k+2?

Mitch Schwartz

yup

Optimizer

how to sort questions by specific things?

orlp

so shouldn't the question be edited then?

Optimizer

like number of answers.

orlp

from 'all even N' to 'all N=4k'

Lembik

14:18

@orlp well... it could be edited or an answer or comment could give the answers for all the other cases :)

Mitch Schwartz

well the odd N case is trivial and the N = 4k + 2 case takes a little thought to prove, but yeah that's an option

orlp

is there an easy way to construct orthogonal vectors to a set of bases?

(not in the rotating part, but the part below it)

New Main Posts

0

Q: Back to the future: Post-quantum cryptography

If you know your programming history, you may know that one of the earliest code golf challenges was to implement RSA encryption. Now, I'm challenging you to code golf an encryption system that is post-quantum. The Task Choose a secure post-quantum asymmetric encryption system and a secure pos...

PhiNotPi

14:36

I just read an interesting article about election fraud, and how they used statistics to detect it in the Iowa caucus.

Geobits

Link?

PhiNotPi

There's actually two related articles: here and here

The basic idea is that, when looking at the precinct level, there should be no relationship between the size of the precinct and the percentages of voters who vote for each candidate.

Mitch Schwartz

oof, the heuristic failed for n = 32

PhiNotPi

this is what an election should look like:

Mitch Schwartz

@Lembik ideone.com/U1VqrC

Geobits

14:42

Interesting. I was going to make an argument regarding rural vs urban, but it looks like they've already accounted for that.

PhiNotPi

the x-axis is cumulative vote count, ordered from small to large precincts

This is the result from the 2012 republican Iowa caucus

Notice how one candidate slopes upwards while all others slope downwards

The logic is that someone looking to change the results of an election focuses on rigging the larger precincts and doesn't attempt to rig the smaller precincts.

Geobits

Hmm. Couldn't you also say that someone looking to win would focus campaigning in the larger precincts?

PhiNotPi

Each precinct is very small, in the above chart, the average precinct only had 67 votes.

Geobits

Oh wow. Iowa isn't Florida, I guess.

PhiNotPi

That would require an extremely detailed campaign strategy.

Geobits

14:49

There were more than 67 people in line at any given precinct all day here.

(well, maybe not all precincts, but many)

Oh wait, this is caucus, not general election. Ok, I can see many fewer votes for that.

PhiNotPi

An important point is to look at the distribution of votes in counties with and without a "central tabulator" machine.

(like on page 5 of my second link) they point out that all counties without a central tabulator machine had flat lines.

Geobits

Yea, just now looking at that.

Sadly, I don't think there's anything to be done without (non-statistical) proof. It's been three years since these papers were published, yet no real action has been taken. I can only assume that the DoJ would be pursuing this if "concrete" evidence was there, considering they're headed by a Democrat and they've been on the losing side of the alleged fraud.

PhiNotPi

15:07

Somebody is currently suing the state of Kansas to obtain the original voting records, since the state has blocked her previous request.

only news article I could find: kshb.com/news/state/kansas/…

I hope something interesting comes out of this.

Geobits

We'll see, but I'm not holding my breath. OpEd from Kansas SecState lays out the state's case in brief.

I have a feeling it'll just be thrown out (unless significant outside pressure is applied).

Martin Büttner

15:30

We've got a little surprise on meta for you...

2

Geobits

For me?

Martin Büttner

plural you

Geobits

Oh look, Alex didn't have to murder Dennis after all :D

feersum

I'm starting to worry that our ecosystem is getting unbalanced. We need more trolls, flamers, and spambots or else our mods might starve!

New Meta Posts

A heartfelt welcome to our new moderator...s!

19

Dennis

15:37

Looks like we need more pizza.

5

Geobits

So we can call you Diamond Dennis now, right?

Martin Büttner

2 days ago, by Martin Büttner

@Calvin'sHobbies I'm not saying why, but you may have posted that a bit too early.

Beta Decay

Woah, bombshell

Well done @AlexA. :D

Doorknob

@NewMetaPosts I'm going to go ahead and pin that

Dennis

@Geobits Dennis Diamond, please.

Beta Decay

15:51

This is a party... We need cake :D

Optimizer

Blue Dennis

Wow, not just Dennis!

PhiNotPi

Achievement get! Diamonds for you

Optimizer

So, 40% of the candidates became mods?

trichoplax

In the end, there can be only, um, two.

Dennis

And all mods were nominated by Alex.

Optimizer

16:01

This is not at all a scalable model!

Beta Decay

16:21

What's Hitler doing in this chat room? :|

Chris Jester-Young

@BetaDecay I hereby invoke Godwin's Law. :-P

Optimizer

Also, Big Brother is watching us.

Beta Decay

picture falls off the wall

trichoplax

Congratulations @AlexA.

Alex A.

@trichoplax Thank you so much! :D

@Dennis Really?

trichoplax

16:36

@AlexA. No :)

Dennis

Yup, two for two.

(You should know.)

trichoplax

Oh - all mods, not all nominations - ignore me...

Alex A.

I never ignore you. <3

trichoplax

:)

@Dennis @AlexA. the blue looks good

Alex A.

:D

trichoplax

16:39

Have you tried out your new powers yet?

Optimizer

javascript:$(".username").addClass("moderator")

^ Everyone gets to be a mod!

Dennis

Well, I looked at them.

Alex A.

I'm still figuring things out

Optimizer

slow...

Geobits

16:54

So if there's no real question in a question, we should close as "unclear what you're asking", right? :P

Dennis

wields close hammer

If we start doing that, main will be empty though. :P

Geobits

Nah, just rephrase them all as "What is the shortest blah blah blah?"

Optimizer

oh, closing that was just a joke?

retracts close vote

Beta Decay

17:19

@Optimizer If you run that does it actually work?

Optimizer

u can run it, u no

Beta Decay

i on fone

Optimizer

yolo

2

Beta Decay

It strikes again :D

Optimizer

I see.

Geobits

17:24

I sincerely hope we don't start posting links back and forth whenever a meme rears its head. The stars will never stop.

Optimizer

I am gonna add this to my about section:

> Originator of 2 PPCG Memes

Alex A.

I'm sure there are more.

Martin Büttner

@Optimizer put it on your CV

Optimizer

@MartinBüttner I don't want to make the "percentage of actually useful content in my CV" less than 1%

Geobits

If it's already low enough that that would push it under 1%, you might as well go all out.

Optimizer

17:34

@Geobits just that line won't, but knowing me, I won't stop there, once started

Geobits

You say that as if it's a bad thing.

Optimizer

Its a bad thing for health.

no job -> no money -> no food

Martin Büttner

@Geobits it might be empty so far

so the current percentage might just be undefined

Optimizer

given that I am working, it can't be empty

Alex A.

"Working" doesn't necessarily imply that you're doing something which increases the percent of useful content on your CV.

Optimizer

17:36

but it still can't be empty

Alex A.

After all, you are in here, where all work is abandoned.

Optimizer

also, even when I am not here, I am still here

Geobits

There are valid reasons to omit certain jobs from your CV. So it doesn't have to have something in it if you're working.

Alex A.

@Optimizer That sounds really deep.

Optimizer

there are other mandatory sections apart from "job experience" too

for ex., Name

Geobits

17:37

Sure, but if you haven't written it yet, it's empty.

Alex A.

Name: Optimizer. Occupation: Llama. Achievements: 2+ PPCG memes.

Pl0x to hire 4 teh jobz

Optimizer

@Geobits since I have a job, I had to have a cv to show to the interviewers.

Geobits

I've gotten at least two jobs without one.

I dunno how it works there, though.

Optimizer

"coz java"

Geobits

Neither were java jobs :D

Alex A.

17:39

@Geobits I've gotten two or three without a CV but I was in my teens. If you managed to do it older then I salute you.

Optimizer

@Geobits that was for me

Geobits

@AlexA. Yea, I meant in my teens. Apparently at a certain age people expect you to "grow up" and "be prepared for an interview" or some such.

Alex A.

So your CV just said "coz java" and you got the job? Nice work.

@Geobits It's BS. All interviews should be conducted by surprise, where the interviewers crawl into your bedroom window and wake you up in the middle of the night.

Optimizer

I'd still be awake in the middle of the night

Alex A.

Do you work a night shift?

Geobits

17:43

@AlexA. Kudos to them for bringing a decent ladder. I'd be impressed enough to hear their pitch.

Alex A.

I laughed at your deleted comment. I saw it before it was deleted.

:23786545 Correct. Cackles maniacally

Yes

Geobits

(removed)

Chris Jester-Young

something something Streisand effect something

Alex A.

As in Barbra?

Chris Jester-Young

@AlexA. Barbra.

Streisand effect

The Streisand effect is the phenomenon whereby an attempt to hide, remove, or censor a piece of information has the unintended consequence of publicizing the information more widely, usually facilitated by the Internet. It is named after American entertainer Barbra Streisand, whose 2003 attempt to suppress photographs of her residence in Malibu, California, inadvertently drew further public attention to it. Similar attempts have been made, for example, in cease-and-desist letters to suppress numbers, files, and websites. Instead of being suppressed, the information receives extensive publicity...

Alex A.

17:48

@ChrisJester-Young That's what I said. :P

Chris Jester-Young

@AlexA. :tuibillboard:

Alex A.

Uh, what?

Chris Jester-Young

Tui is a New Zealand brewery that's famous for its Yeah Right ads. Here's some examples: tui.co.nz/competitions-and-events/yeah-right-gallery

@AlexA. So when people say "Tui billboard" in New Zealand, they're saying "yeah right". :-)

Geobits

A famous New Zealand brewery. Yeah right. :P

Chris Jester-Young

The winners of that contest ("I just bought my first home in Auckland! Yeah right." and "I'm saving for a house in Auckland. Yeah right.") are hilarious. If you're a New Zealander, you'll instantly get it. :-)

@Geobits Touché.

TheNumberOne

18:09

@Geobits I found a java program that is shorter than yours for Hello, World!

Geobits

I'm trying to run it, but I can't without declaring both the class and constructor public (and fixing what I assume is a mistaken missing ;). How are you getting it to run?

> load: H.class is not public or has no public constructor.
> java.lang.IllegalAccessException: Class sun.applet.AppletPanel can not access a member of class H with modifiers ""

It works if I change it to:

public class H extends java.applet.Applet{public H(){System.out.print("Hello, World!");}}

But then it's not shorter.

TheNumberOne

@Geobits Looks like it won't work. That's what happens every time I don't test my code.

Geobits

Well damn. I was hoping to learn a new golfing trick :(

Optimizer

18:36

How to call an Undefined Function?

Geobits

You don't. It calls you.

Optimizer

No. You can. @UndefinedFunction

Beta Decay

18:49

I feel like I have -15 tattooed on my forehead, reading Optimizer's latest edit :D

3

Rainbolt

This made me laugh i.imgur.com/SkZTLzH.png

(A lot of stupid stuff makes me laugh though)

Can the author even see his deleted post?

Peter Taylor

@Lembik That's on my mental list of things to look at at some point.

Martin Büttner

@Rainbolt yes

Lembik

@PeterTaylor Thanks! I am trying to resist posting a new challenge which is an optimization version of that old one

that is, take n = 40 say and try to find the smallest number of rows that work

it seems there are some nice heuristics which might be helpful for such a search problem

saying as the problem seems to be still wide open

undergroundmonorail

19:05

I wrote pb code that crashed cmd.exe. Huh.

Optimizer

@BetaDecay That seems like the most optimal meme image for -15!

trichoplax

I followed some links starting from HNQ and now my mind is broken

2

Optimizer

such a ho!

Beta Decay

@Optimizer Haha I'm happy with it :D

@trichoplax Mathoverflow is the scariest place on SE ;)

trichoplax

@BetaDecay Indeed. I expect to be scared by scary questions, but "what is the volume of a ball" I thought I was safe with...

Beta Decay

19:13

Hahaha you know you should have a NSFW warning on that link

trichoplax

NSFL

Optimizer

NSALT

trichoplax

Lost...

Beta Decay

NSFNMW

Optimizer

Lost...

undergroundmonorail

19:21

the worst thing about coding in a language you designed is not knowing if your program has a bug or if your language has a bug

Optimizer

or if u urself have a bug

undergroundmonorail

oh dam

trichoplax

@undergroundmonorail At least if you designed both you know who to blame :P

Peter Taylor

@trichoplax Gödel?

undergroundmonorail

guido van rossem, for the clearly flawed language the interpreter is written in ;)

trichoplax

19:24

@PeterTaylor For the concept of languages having a bug?

Geobits

I normally blame Heisenberg whenever I'm uncertain of anything.

Peter Taylor

@trichoplax Something like that.

@Geobits That's unfair. You should blame Gabor.

trichoplax

Wikipedia can't help me with that one - I just get lots of results for shoes

Geobits

@PeterTaylor I'm not certain I should, so I blame Heisenberg.

trichoplax

I'm going to guess that's a Fourier transform joke, but I'm frequently wrong

Peter Taylor

19:31

@trichoplax More or less. The Heisenberg inequality (or Heisenberg-Gabor-Weyl inequality) is a particular case of a general Schwartz inequality related to Fourier transforms.

Beta Decay

You lost me at Fourier transform ;)

Geobits

... says the guy who just wrote a language named Fourier.

trichoplax

Technically I did get that from Wikipedia - I was reading up on Fourier transforms last week in an effort to think up questions for the Computer Graphics private beta, so I had a vague recollection that there is an uncertainty principle there

Beta Decay

Haha I get the basic concept but I dunno how to apply it

Geobits

My only real experience with them was doing (shoddy) frequency analysis on audio files to generate on-the-fly guitar hero style tracks (for an android game).

Beta Decay

19:34

Haha that sounds pretty awesome :D

And have you finished that game?

Geobits

Yes and no. It's playable, but... programmer art FTW.

Also, haven't touched it in a few years. Would probably have to update it for newer Androids. I can't imagine the Honeycomb-era code is going to be very smooth now.

Beta Decay

I've looked on the Play Store but they don't really work too well

trichoplax

Should I tell you about that typo or wait and then star it??

:)

Geobits

Mmmm. Homeycomb.

Rainbolt

Today is a nice day

trichoplax

19:37

The urge has worn off now

Beta Decay

No, that was me

Geobits

Yes, that was not me.

Optimizer

Yes, that was you.

Rainbolt

It was Geobits, with a pipe wrench, in the Nineteenth Byte.

5

trichoplax

Please no

Geobits

19:39

No. A one-off occurence is not a meme.

undergroundmonorail

tread carefully. memes being a meme is not a good look

trichoplax

@Geobits You had to say it.

Beta Decay

Wait what?

Optimizer

@undergroundmonorail its yingluck

undergroundmonorail

I wasn't here for the dawn of yingluck, but I think "yingluck" would be a dope name for a rapper

Geobits

19:41

@trichoplax Oh wait, does that encourage people to do it more often so it gains meme status? If so, that was never my intent, and I shall atone in the proper manner if it comes to pass.

Optimizer

it shall never pass

ever

trichoplax

Memes don't pass

Geobits

So they run the ball?

Beta Decay

1, 2, 3 and to the 4
Undergroundmonorail and Yingluck is at the door

Rainbolt

Evidence

trichoplax

19:42

@Geobits I'm not sure this is the kind of environment where that can be described as a ball

undergroundmonorail

i wish my murder weapons had branding that slick

Geobits

I'm being framed! My pipe wrench is not painted; just bare metal.

Beta Decay

It was

Until you stoved Dennis' head in for the spot as mod

trichoplax

Now I'm in a ~~dystopian~~ utopian future where everything is branded with Geobits' downvote symbol

Geobits

@BetaDecay You have me confused with Alex. Just the threat of an... accident... from him was enough for SE to capitulate and give him a diamond :P

Rainbolt

19:45

Dennis has too much reputation to be a victim of the downvote pipe wrench

Beta Decay

It was Justin! He killed Quincunx and took his account

Rainbolt

I remember that name....

Who is Quincunx now?

Beta Decay

Justin

Geobits

^ that guy

Rainbolt

O...

I wish ProgrammerDan would come back

trichoplax

19:48

Is ProgrammerDan the same as DanTheMan?

Beta Decay

I wish m.buettner would come back

trichoplax

He's right there...

Beta Decay

Who?

trichoplax

m

Beta Decay

a

trichoplax

19:48

r

Geobits

t

Beta Decay

i

trichoplax

n

Beta Decay

b

Dennis

ü

trichoplax

19:49

t

Beta Decay

t

Geobits

ner

Beta Decay

d

trichoplax

ner

Rainbolt

butt nerd?

How many times has he heard that in his life I wonder

Beta Decay

19:50

Hehe you remember that Geobits?

Geobits

I remember all.

Rainbolt

I grew up being called Rainbow

undergroundmonorail

oh yeah i remember that

Optimizer

I grew up being called Llama!

undergroundmonorail

i remember feeling really creepy about accidentally figuring out your name but now it's in your username so i'm not weird any more

Geobits

19:52

I grew up being called

Beta Decay

@undergroundmonorail Whose name?

Rainbolt

Awww, I missed a ping

undergroundmonorail

rainbolt

Optimizer

@Geobits no one used to talk to you at all?

Rainbolt

Oh yea. I let my name loose in a Google Docs

Geobits

19:52

@Optimizer Why would I be called if nobody was talking to me?

Beta Decay

@Rainbolt Your name is actually Rainbolt?!

Rainbolt

Yes

undergroundmonorail

@Rainbolt ...that wasn't even how i figured it out haha

Beta Decay

Sweet

Optimizer

@Geobits you were called <null>

Geobits

19:53

Still better than being a llama.

Rainbolt

@undergroundmonorail How did you find out? My link to my company page? The fact that my profile says I play Magic, along with a tagged picture of me winning a draft?

Geobits

I found it from your company name and town, which led me to the company page/profile.

undergroundmonorail

it was the link to your company page, but i only narrowed it down because i happened to remember a file in the controller for the wolf KOTH that referenced a windows path that included your username (i.e. first name) and there was only one person with that first name in a dev role

Geobits

I'm totally not a stalker, by the way.

trichoplax

@Rainbolt Your company page has photos of some of the staff

Peter Taylor

19:55

@Geobits The correct term's doxxer, right?

Rainbolt

It has photos of all of the staff I think

Geobits

@PeterTaylor That depends. My next comment was going to be to remind him to take out the trash tonight. It's getting full.

trichoplax

I just quickly linked there from your profile - I didn't think to check if the number of employees is the same as the number of photos...

undergroundmonorail

@Rainbolt also i googled your minecraft name because while i was pretty sure it was you, i wasn't 100% certain, and we had already been talking for a couple minutes so i didn't want to be like "by the way who are you". that's the story of how i accidentally found your facebook. sorry

Rainbolt

How dare you

trichoplax

19:57

So in short, none of us are stalking you. Everything is perfectly explicable.

Rainbolt

Go "not stalk" Martin. He's way cuter without his scarf covering him up.

6

Geobits

It's a bit long distance for me. Texas isn't close or anything, but...

Rainbolt

I play Magic so by default I cannot be worth stalking

Mitch Schwartz

@Lembik for n = 32, the optimal is 14

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