The Nineteenth Byte

dzaima

19:03

@Dehodson not sure whether it'll work for your use case, but how about

(d,z)=>document[l='querySelectorAll'](`#${d} tr`).forEach(x=>[...x[l]('td')].some(y=>(x.style.display=y.innerText==z?'inheri‌t':'none')[0]=='i'))

?

Dehodson

@StewieGriffin True, I suppose I could always ask the JavaScript chat room on the main stackoverflow site.

@dzaima Nice use of the ... operator! Didn't even cross my mind. That cuts it down a whole 7 bytes!

dzaima

how about replacing [0]=='i' with [4]?

Hat Wizard

Anyone interested in contact?

DJMcMayhem

@HatWizard I'd like to, but probably not today. In general, 0-6 UTC is much better for me to play

Cows quack

@HatWizard yes

dzaima

19:16

@HatWizard in a bit maybe, have to reread the rules

mınxomaτ

Wah, sudden Twitter redesign.

Wow, they really tried very hard to make everything take one more click.

AdmBorkBork

19:34

/me reading highly technical article on a feature of Exchange ... 1 comment at the bottom:

> Wow, neat article! What does Exchange do?

Pavel

You mean Microsoft exchange?

AdmBorkBork

Right. Like, how did this person even stumble across this article in the first place?

Not as bad as the one time the comment said something like "My McAfee says that I have a virus. Please call me at number so I can get this fixed."

DJMcMayhem

@AdmBorkBork Oh, I read that wrong. I thought you said "I comment at the bottom"

AdmBorkBork

Hahaha

Adám

Wait, aren't meta downvotes free (as in they don't cost rep to cast)?

Erik the Outgolfer

20:07

@AdmBorkBork I don't get that...

mınxomaτ

Flippin heck. Now GitHub rolled out a new design, too.

Stop changing all the things.

AdmBorkBork

@EriktheOutgolfer Topics here always seem to gravitate to natural languages or food. But you said what's "on topic" for the room, not what is "popular" in the room.

Erik the Outgolfer

I mean, I don't get the joke

@mınxomaτ tbf, it doesn't look all that different

AdmBorkBork

Things that are popular in the room aren't on-topic for the room. But we do the topics anyway.

That's pretty much it. Nothing beyond that point.

Erik the Outgolfer

like, you're so used to mentioning that

@Dehodson I think they will yuck at that golfed code...

they'll be like, "do some code review first" :P

DJMcMayhem

20:12

Personally, I've always thought that SO chat was rather toxic.

But 🤷 that's just me

Mr. Xcoder

It's not just you

AdmBorkBork

Ooo. TIL that the new Microsoft Docs has a Dark theme

Erik the Outgolfer

well, they're not particularly used to seeing ~~garbage~~ art :P

@AdmBorkBork docs.microsoft.com?

that looks just like the usual Mi¢ro$oft theme...

AdmBorkBork

I think you have to click into an article to get to the preference drop-down

Random article, then "Theme" on the right-hand column

Dehodson

@dzaima [4] worked :) 139 bytes!

@EriktheOutgolfer So sad they can't appreciate the fine art of code golfing :P

Erik the Outgolfer

20:18

well, a dark theme isn't exactly just for preference, visually impaired people exist

however, it's quite nice to have that option, as not many have it

Pavel

@AdmBorkBork There's been a dark theme since at least 2016

AdmBorkBork

Then I'm one of today's lucky 10,000

Pavel

Good for you

Mr. Xcoder

Suggested WW name: Cat Wizard

4

quartata

wtf

Hat Wizard

20:24

Please don't flag

AdmBorkBork

Really? That got flagged?

Pavel

I meant to star that, misclicked, and hit the flag button :(

AdmBorkBork

That's a 50 DKP minus!

Erik the Outgolfer

but you need to confirm your flag via a dialog box

Pavel

I just clicked ok without looking

AdmBorkBork

20:26

Just like a EULA

DJMcMayhem

@Pavel That's him officer, we caught him red-handed

Admitted it and everything

Anush

hmm... it would be great to have a challenge where you counted the number of clock cycles your code took

Pavel

Years of pointless popups have trained me to ignore webpage alerts.

Erik the Outgolfer

tip: never ignore dialog boxes, they may be important

and also never ignore popups which don't look like ads at first glance

AdmBorkBork

@Anush I think we've already had one like this

Erik the Outgolfer

20:27

(yes, you should have a first glance)

Anush

@AdmBorkBork oh!

@AdmBorkBork I am sort of surprised as it's quite a hard thing to get right

codegolf.stackexchange.com/questions/47290/… I wonder if that would be closed these days

I suspect so

dzaima

@Anush atomic-code-golf kind of fits

Anush

@dzaima interesting

Oh I like codegolf.stackexchange.com/questions/143822/…

we need more questions that ask code to prove things!

Mr. Xcoder

proof-golf

Erik the Outgolfer

it's not code they ask for, it's the proof itself

Anush

20:31

nice

is that valid on ppcg still?

not scoring the code that is

dzaima

@Anush it's objective, so yes

Erik the Outgolfer

it's been decided that it's valid, even though it's not technically programming

Anush

that's cool.. makes me love ppcg even more

Erik the Outgolfer

if you want to make a non-programming related tag you think has a possibility to be valid, you should ask over meta

Anush

although there are very few proof-golf questions it seems

3 ever!

Erik the Outgolfer

20:33

it looks like only Hat Wizard is currently interested in posting those, and only once per year

if you think you have made a difficult, but answerable proof-golf question, feel free to post it!

Anush

I am just wondering if finite group theory could be a rich supply of those

why difficult?

Erik the Outgolfer

because there aren't many "programming languages" you can write proofs in, and, well, no fun proving something trivial

Anush

I mean what about simple statements like... If G is a group in a way that we are given x, y ∈ G, then prove (x ⋆ y)^-1 = y^-1 ⋆ x^-1

the challenge is to write code that supplies the proof I guess

Erik the Outgolfer

I'm not really sure if you can post it without some axioms

Anush

hmm.. maybe I haven't fully understand the tag

Erik the Outgolfer

20:36

> There should be a complete and unambiguous set of well-defined axioms and a definition of what constitutes a single valid step in the proof.

Anush

@EriktheOutgolfer Oh right.. first I would spell out the standard axioms of group theory

I think group theory gives you that for free

Mr. Xcoder

proof-golf requires two things: 1. the thing to be proved 2. a set of axioms 3. a winning criterion (usually, least number of steps)

Anush

If ‘a’ and ‘b’ are two elements in G, then a . b will also belong to G, If ‘a’, ‘b’ and ‘c’ are in group G, then a . (b . c) = (a . b) . c, For any element ‘a’ in G, there exist an element ‘I’ in G, such that a. I = I . a = a. ‘I’ is called the identity element of G., For every ‘a’ in G, there exist some ‘b’ in G such that a . b = b . a = I, where ‘I’ is the identity element of G.

that's it in terms of axioms

so now it seems we can come up with our favourite statements in finite group theory and ask for code the gives a proof

I suppose either you could score the length of the code or the length of the proof

Erik the Outgolfer

then there's the valid step definition

Anush

a step is just an application of one of those 4 axioms

dzaima

20:39

@Anush definitely proof length ~~otherwise brute force wins all~~ oh right brute force wins then too

Erik the Outgolfer

for example, here, apart from a normal "step", you can also do "Modus Ponens"

Anush

@dzaima true although if you require that the code runs to completion that rapidly becomes impossible

so any proof that is more than a few lines long is not going to be found by brute force I feel

Erik the Outgolfer

may I ask why would you ask for code instead for a proof itself?

it's sorta like asking for code to produce the code that completes the described task

dzaima

^^ solves the brute force problem as the answerer has to be able to create the proof before the end of the universe

Hat Wizard

Brute force can be hard, for example all of my proof-golf questions have an infinite search space for a brute forcer.

Anush

20:42

ah an expert :)

@HatWizard how do you feel about finite group theory proofs for ppcg?

basically any simple axiomatic math system seems amenable to this game

Hat Wizard

I like it. That's why I asked about it :)

Anush

unless the proofs just become too hard to find I suppose

Erik the Outgolfer

btw, I'd first recommend sandboxing such a question, because it's not that standard

Anush

@HatWizard oh have you done group theory ones?

Hat Wizard

Actually it was ring theory now that I remember

or rng theory

Anush

20:44

@HatWizard right.. that's harder

what is rng versus ring?

Hat Wizard

Rings have identity rngs don't

Anush

oh I see!

Erik the Outgolfer

looks more like a pun, Ring - Identity = Rng

Anush

so.. what is a good theorem of group theory we can hope to prove by code :)

Hat Wizard

I don't know, group theory is a bit hard, it doesn't have many axioms.

Anush

20:46

@HatWizard I was hoping that might make things easier in a way

Hat Wizard

It just means that most things tend to be trivial or involve more complex proof techniques.

Anush

@HatWizard right.. let me see if I can something in the middle

(just discovered what a loop is)

Hat Wizard

loops are fun

My next proof golf is probably going to be on Existential Graphs.

Anush

nice

is it hard to count the number of groups of order n?

hmm

maybe :)

Hat Wizard

yes group counting was a big area of focus for a long while

Anush

20:54

@HatWizard codegolf.stackexchange.com/questions/161172/… is very nice but I wonder if it could have been made simpler

I mean the question

does it really need all that machinery?

Hat Wizard

It is very light on machinery

It has 3 rules.

Anush

true.... maybe the statement is just hard to prove

I remember proving something like A->A->A->A

which was a dozen or so lines

Hat Wizard

I can prove that in 3.

Well depends where the parens are.

Anush

then it can't have been that exactly :)

is there a version that takes >3 lines?

Hat Wizard

Yes A->(A->(A->A)) requires 9 lines

Anush

20:57

that was most likely it then

it might be nice to make a version that asks for code

which you then run on some test caes

Hat Wizard

(A -> (A -> A)) -> A under some definitions takes more lines. Because it is not provable.

Anush

and score by proof length

@HatWizard :)

Hat Wizard

For uni I designed an algorithm that will always find the shortest proof in a Hilbert system like this.

Anush

it would be nice to have a theorem prover as an answer to a ppcg queston

@HatWizard you are the perfect person to pose the challenge! I am often amazed by the quality of answer to university level questions here

Erik the Outgolfer

@HatWizard that's just lies...

Anush

21:00

the answers to codegolf.stackexchange.com/questions/157049/… seem to be the only existing code in the world to compute the Hafnian quickly

as an example of the quality here

I tried to read the associated paper and failed

oh I thought of something related and fun.. code that can solve recurrence relations

using whatever the most general version of the master theorem is

Anonymous

@Anush There's a language for that, I think

Anush

@Mego oh! I would love to know

I can't even remember what the theorem is called

stars with an A I think :)

Akra–Bazzi method

In computer science, the Akra–Bazzi method, or Akra–Bazzi theorem, is used to analyze the asymptotic behavior of the mathematical recurrences that appear in the analysis of divide and conquer algorithms where the sub-problems have substantially different sizes. It is a generalization of the master theorem for divide-and-conquer recurrences, which assumes that the sub-problems have equal size. It is named after mathematicians Mohamad Akra and Louay Bazzi. == Formulation == The Akra–Bazzi method applies to recurrence formulas of the form T ( x ) ...

or that creates random recurrence relations that can be solved with that method

(needs thought)

Anonymous

Request for feedback: codegolf.meta.stackexchange.com/a/16411/45941

Erik the Outgolfer

the test cases kind of don't make it clear about i...

Anonymous

What isn't clear? i is a column index

Erik the Outgolfer

21:11

the thing that makes it unclear is that i doesn't exist in the test cases

that is, unless the dictionary keys are different is

Anonymous

Oh, I messed up and didn't include that input

Anonymous

Fixed

betseg

21:34

im desperate plz help

im on android, just flashed a custom rom, i can install every app i tried except 3 specific ones

Zacharý

And those are?

betseg

google fit, google news, nova prime

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