The Nineteenth Byte

Anonymous

6:00 AM

Coffee + Baileys is a wonderful combination

DJMcMayhem

@Mego isn't it a little late for coffee?

Anonymous

@DJMcMayhem What madness do you speak? It is always the right time for coffee.

DJMcMayhem

@Mego I love coffee, and I 90% agree with you but I would never have coffee at 1AM (which I think is your time zone)

Anonymous

Well when you consider that I'm going to be up for like 3-4 more hours, it's perfectly fine

Anonymous

It's 1 AM in my time zone, but not 1 AM according to my internal clock

DJMcMayhem

6:08 AM

How'd your internal clock get so messed up?

Sherlock9

Coffee lasts like 8 hours or something

Simple. Bit by bit

Anonymous

@Sherlock9 Please. Byte by byte.

DJMcMayhem

What time is it wherever you are sherlock? (If you don't mind my asking)

Anonymous

@DJMcMayhem It's perfect for my schedule as a self-employed software developer. Talk to client(s) in the afternoon, spend evening with my wife, then work at night.

DJMcMayhem

That actually sounds amazing

Sherlock9

6:11 AM

1 pm

Mego, did you accept LN's PR about nCr yet?

DJMcMayhem

@Sherlock9 oh wow, that's a 13 hour difference from me. O_o

Sherlock9

This pull request: github.com/Mego/Seriously/pull/68

Anonymous

@Sherlock9 I Actually just saw it :P

Sherlock9

Harhar

Anonymous

I dunno how I missed the email

Sherlock9

6:13 AM

Yeah, I'm well on the other side of the world from the Americas

DJMcMayhem

Yeah, I'm most active in here while you're presumably asleep

Helka Homba

Who has the fastest rocket in the west?

DJMcMayhem

Speaking of sleep, that sounds really nice right now

Helka Homba

(just don't mention my new q to Geobits since I'd expect downvotes for a boring ascii art challenge)

DJMcMayhem

@HelkaHomba I was going to go to sleep, but I have a language that's good at ascii art

So I think I won't

New Main Posts

6:20 AM

2

Q: This isn't rocket science

Write a program or function that takes in a single-line string. You can assume it only contains printable ASCII. Print or return a string of an ASCII art rocket such as | /_\ |E| |a| |r| |t| |h| |_| /___\ VvV with the input string written from top to bottom on the fuselage. In this ...

Anastasiya-Romanova 秀

@DJMcMayhem In my case it's the other way

DJMcMayhem

What do you mean?

Anastasiya-Romanova 秀

Why on earth the adult user want to meet minor?

@DJMcMayhem In my case, I'm the one who want to meet them

Anonymous

@HelkaHomba Actually, I do.

Anonymous

@Anastasiya-Romanova秀 Almost certainly for a very bad, immoral reason. Hence their concern.

Anastasiya-Romanova 秀

6:25 AM

@Mego My parents told me to be careful with people out there. That's why the install a very aggressive internet filter

DJMcMayhem

;_; V.tio is not working right so I have to do it locally...

Sherlock9

That reminds me. @Dennis Can you pull Actually?

Hello ibubi

ibubi

hello guys

Anonymous

Heyo

DJMcMayhem

Hello!

Anonymous

6:33 AM

slurp.chomp.comb... Perl is weird. — Mego 1 min ago

ibubi

i have got a question about code golfing

DJMcMayhem

Go for it

Anonymous

Ask away. Good luck finding the actual answer in the inevitable pile of puns, jokes, and sarcasm.

Sherlock9

@Mego I get 65 bytes on your comment. Thanks for the help :D

Anonymous

@Sherlock9 You missed a leading space in the string

Anonymous

6:37 AM

The needle needs to have 2 spaces of indentation

Anonymous

SE apparently gobbled one of them

DJMcMayhem

Hmmm. I golfed two bytes off, but I posted my answer less than 5 minutes ago.

I want to use the strikethrough header, but it won't make sense in revision history...

Dennis

@Sherlock9 Pulled.

Anonymous

@Dennis Danke

ibubi

I have been observing the challenges on code golf, i am at very beginning of this stuff and it is interesting indeed. What should a beginner look at to learn and write golfed codes?

DJMcMayhem

6:38 AM

Hey @Dennis Do you have any idea what causes this strange behavior on v.tio?

0

A: This isn't rocket science

V, 41 bytes ys$_òlé òÎysl|>> Hr/$r\YO |GpXl3älo VvV Try it online! Note that for some reason, the online interpreter is producing unexpected results. I have tested and can confirm that this program works correctly on my local version, and I'm investigating the problem with the online interpre...

Anonymous

@DJMcMayhem Carp, that means I have to golf two bytes off of mine

Anonymous

@ibubi Check out the tips page for your favorite language (if there is one).

DJMcMayhem

@ibubi Use whatever language you enjoy the most! There are a lot of dedicated golfing languages out there, but there's still a lot of competition within a single language, which can be just as fun.

I answered exclusively in python for a loooong time.

Dennis

@DJMcMayhem Huh? It works sometimes and sometimes it doesn't...

Is that what you're talking about?

DJMcMayhem

Yeah

It works fine locally.

Sorry. It seems like V breaks more often than most of the TIO languages...

Anonymous

6:44 AM

@DJMcMayhem Seriously broke very frequently, but that was pre-TIO

DJMcMayhem

Yeah, V used to be horribly buggy since I implemented the commands in python while it had extremely limited access to vim's internals. Now that I've migrated to vimscript, all of that's gone.

Fatalize

I've had 3 different results for that V program so far

DJMcMayhem

I've seen like a dozen, and they're all pretty weird.

@Dennis Does it work correctly for you locally? I'm worried it might possibly be a timing issue since I'm testing on faster hardware and I had seem some weird timing errors when I tried to implement some more advanced features.

Dennis

Like race conditions?

DJMcMayhem

Like two keystrokes being sent in before the first one has time to fully process.

Would that count as a race condition?

Dennis

6:52 AM

Yeah.

DJMcMayhem

Then yeah, there might be some race conditions. Hopefully there might be a way to force it not to be asynchronous, which is ironic since the whole point of neovim is to provide asynchronous plugins.

Dennis

Hm, I SSHed into TIO, and its better, but still not stable.

Anonymous

Hmm... I have a very strange question that I don't know the answer to.

DJMcMayhem

:( I have no clue how to fix that

It's weird that this particular issue has not come up before.

feersum

Try retrovim? :P

Anonymous

6:56 AM

Does anybody know of a single-byte encoding that contains newlines (\n), the Venus symbol (♀), and Greek lowercase alpha (α)?

DJMcMayhem

One possible (but terrible) solution would be to put a time.sleep(0.1) between each key

Anonymous

If I can find one, I have a 39-byte Actually solution

DJMcMayhem

@Mego ... Uh, why?

feersum

How could such an encoding help you?

Fatalize

If you could select the encoding you use for a language at will, that would be ridiculous

Anonymous

6:58 AM

Because the way Actually's parser works now is a little weird, but it sometimes comes in handy. It doesn't Actually matter what encoding is used for the input - only the characters matter. I have a 39-byte Actually solution to the rocket challenge, but it uses all three of those characters. CP437 doesn't have newlines.

feersum

How can the encoding not matter?

Anonymous

So any single-byte encoding can be used for Actually, but you'd be restricted to the subset of CP437 that is also present in the source encoding

Anonymous

Yes, source code

Dennis

CP437 has newlines. The 32 control characters are usually represented by dingbats, but 0x0a is still a linefeed.

Anonymous

If you were to run abcdþ as an Actually program, it would recognize abcd as valid commands, but completely ignore þ, since it's not in CP437.

Dennis

7:00 AM

@DJMcMayhem Even if terrible, it would at least allow us to determine if this Heisenbug is a simple race condition.

Anonymous

@Dennis The version of CP437 that Actually uses has the dingbats for the control codes. 0x0A is ◙.

DJMcMayhem

@Dennis Do you mean trying that to test it out, or to leave it that way?

Would you like me to create another branch?

Dennis

@Mego Oh, does Actually do the conversion internally?

@DJMcMayhem At least to test it. If the problem doesn't come up in other challenges, there's no need to leave it in. A different branch sounds good.

Anonymous

@Dennis Sort of. It encodes the source code in UTF-8 and looks up the ordinals via indexing into a 256-byte string representing CP437.

Anonymous

It's one of the greatest, dumbest ideas I've ever had.

Dennis

7:04 AM

But there's also a way to use a different encoding, no?

Anonymous

What do you mean?

DJMcMayhem

I wonder how long too sleep.

I think 0.1 sounds good

Leaky Nun

@DJMcMayhem have you read the three programs I sent you?

Sherlock9

@Dennis Thanks a bunch!

I finally wrote my Actually Bernoulli answer :D codegolf.stackexchange.com/a/91190/47581

Anonymous

@DJMcMayhem That's going to heavily depend on the machine it runs on. You'd be better off using actual synchronization via locks/mutexes.

DJMcMayhem

7:07 AM

@LeakyNun I glanced at them, but I was watching a futurama when I got the notifications, so I didn't feel like looking at them in detail.

@Mego Oh absolutely, but I'm not sure of how to do that because of the weird disconnect between sourcing the file in python and doing all the work in a different program.

This is just for testing

Dennis

@Mego Is there any way to store code in a file that is not encoded in UTF-8?

Leaky Nun

@DJMcMayhem I still have no idea how to swap the top two items in the stack

even when using an auxiliary stack

(of course I would prefer not to use one)

Also, have you looked at my 46-byte submission?

DJMcMayhem

Wow. This is an extremely impressive answer. — DJMcMayhem 11 mins ago

Anonymous

@Dennis Yep. Just use whatever encoding you want, and run it with seriously -f code_file

Leaky Nun

@DJMcMayhem so the swap?

Dennis

7:12 AM

@Mego So if I use a CP437-encoded file, it will still convert 0x0a to a dingbat?

DJMcMayhem

Eamon came up with this:

2 hours ago, by Eamon Olive

@DJMcMayhem That doesn't do it. It moves them to the other stack to keep them in place the optimal solution is ({}<({}<>)<>>)<>({}<>). I had a proof of this but by harddrive was borked so you'll have to take my word that its optimal.

Anonymous

But be aware that any characters present in the source code that are not also present in CP437 will be ignored if they are used as commands (i.e. not in a string literal or something similar).

Anonymous

@Dennis A CP437-encoded file will show 0x0A as a dingbat, unless your system is doing something odd and using the pseudo-CP437 encoding that has control codes instead of dingbats.

DJMcMayhem

I don't see what the point of coming up with this language was. I haven't written anything interesting in it, I'm not good at it, and I don't understand all the programs that other people have written in it. :P

Leaky Nun

@DJMcMayhem I wrote an explanation

DJMcMayhem

7:14 AM

Doesn't mean I understand the solution, haha

Leaky Nun

@DJMcMayhem that swap is very good

Anonymous

If your system uses the ASCII-compatible pseudo-CP437 encoding that has control characters instead of dingbats, then no, it will see 0x0A as a newline and not a dingbat.

Leaky Nun

I'll try to write a one-stack solution but I still cant

DJMcMayhem

That would be insane. One stack solutions are hard

Leaky Nun

@DJMcMayhem well, basically the any quadratic sequence can be expressed as partial sums of linear sequence

I wrote a one-stack to my answer

lets say i have 43

i want to generate 43+43+42+42+...+1+1+0+0

DJMcMayhem

7:17 AM

@Dennis I added sleep to a new branch named debug. Do you wanna test that?

Leaky Nun

so I just keep pushing those things and popping them

Dennis

@Mego But how to display 0x0a is the terminal's choice. Afaik, all recent terminals should display a linefeed. For example, iconv converts CP437 0x0a to UTF-8 0x0a.

Leaky Nun

and those are added automatically inside the parentheses

Dennis

@DJMcMayhem Pulled and switched. Pretty slow, but it seems to be working.

Anonymous

@Dennis Let me try to be a little clearer: if Python 3 on your machine reads a CP437-encoded file and sees 0x0A, it should read it as the dingbat. If it doesn't, you're going to have issues, because the API that Python 3 is using uses the "modern" code page and not the original code page. It depends largely on what your system thinks 0x0A in CP437 is. It's an OS-level issue, more than likely.

Leaky Nun

7:21 AM

I remember once we had beautiful programs to swap the values of two varianles

Does anyone remember?

Anonymous

I have no issues on Windows (Windows 10, to be specific) with loading CP437 files in Seriously - they have dingbats, not control codes.

DJMcMayhem

@Dennis OK cool. Could you switch back to master? I don't mind having a bug on one answer so that all the other answers can be faster

Dennis

@DJMcMayhem Maybe try setting it to something more sensible, say 0.01.

Fatalize

If there's a bug on that answer, there's probably a bug on lots of future answers

Leaky Nun

int a=4, b=5;
//code without temp var
assert(a==5 and b==4)

DJMcMayhem

7:23 AM

Would that be enough to fix it?

muddyfish

why is chat broken?

DJMcMayhem

Oh, that's not quite as slow as I thought.

Dennis

@Mego But Python just reads the byte 0x0a as input and prints the byte 0x0a as output. Python cannot possibly know how the terminal displays that byte, nor does it care.

@DJMcMayhem Only one way to know for sure.

DJMcMayhem

I think I'll try making the sleep time lower, and only activate it with the --safe flag. For now, I don't really care to do any testing since I'm going to bed

So don't switch yet

muddyfish

Dennis

7:27 AM

Did you try refreshing the page?

Anastasiya-Romanova 秀

Why did sometimes the chat display flicker? It's like there's a glitch

Leaky Nun

int a=4,b=5;
a=a+b; //a=9, b=5
b = a-b; //a=9, b=4
a = a-b; //a=5, b=4

Sherlock9

Bits of chat have been broken for years

muddyfish

@Dennis weird, it's fixed after that

Dennis

Maybe your clock got adjusted. Chat really doesn't like that.

DJMcMayhem

7:31 AM

^

muddyfish

It might have done

DJMcMayhem

I just noticed the same thing recently

Dennis

I should definitely stop screwing with my system clock.

►

Anonymous

@Dennis When Python 3 does b"\x0a".decode("cp437") == "◙", it's using a lower-level (aka OS-level) API to do the conversion, which ultimately decides if that expression evaluates to True or False.

muddyfish

I should definitely stop screwing with my system clock.

►

actual link (not in edit mode)

Dennis

7:34 AM

Yeah, I fixed that. That's one of three YouTube videos I've uploaded. Don't really know the interface...

muddyfish

make sure the link has watch?v= in it

Dennis

Wth?

Copyrighted content was found in your video.
The claimant is allowing their content to be used in your YouTube video. However, ads might appear on it.

Anonymous

@Dennis Copyright trolls. YouTube is notoriously bad at allowing fake copyright claims through.

Dennis

No, it's on Super VIM and the claim is from Nintendo.

I'm just wondering how they found it. The video is unlisted...

@Dennis super vim?

7:38 AM

Anonymous

YouTube's very overzealous copyright detection algorithms

Anonymous

Is that Vim running on an SNES?

Dennis

Well, I guess that's one way not to get sued.

muddyfish

MY GOD THERE ARE ADVERTS

Anonymous

Thankfully, my adblocker takes care of those annoying, extremely obstructive ads that YouTube shows.

Dennis

7:40 AM

Yeah, mine too.

DJMcMayhem

@Dennis 1. What colorscheme is that? 2. I thought you hated vim

Anonymous

Disliking a software product is no reason not to try to run it on hardware that it wasn't intended to run on :P

Dennis

@DJMcMayhem No clue. I pieced a few of Doorknob's GIFs together.

Anonymous

I dislike Java, but I am sure as hell going to try to get the JVM running on my N64 at some point.

Dennis

@Mego No. I said once to Doorknob that vim sounded like playing Super Mario in your source code, so I took a few of his screen captures and added the background music from Super Mario Bros.

DJMcMayhem

7:43 AM

It looks very similar to Gotham which I use for GUI currently

Anonymous

@Dennis Oh, shame on me for not actually watching the video.

Anonymous

YouTube is especially good (bad?) at "detecting" copyrighted music in videos. I say "detecting" because it often goes awry and flags stuff for the wrong reason, because its algorithm thinks the audio sounds close enough to copyrighted music.

Dennis

It was dead right here though.

Leaky Nun

@DJMcMayhem EUREKA: (({}({})))({}<({}[{}])>)({}[({})])

DJMcMayhem

@LeakyNun Woah, is that a one stack swap?

Leaky Nun

7:54 AM

@DJMcMayhem yes

DJMcMayhem

@LeakyNun That's amazing. Do you happen to know how to do a "less than" in bf?

Stack safe that is

Leaky Nun

@DJMcMayhem what is stack safe?

I'll consider it

Dennis

Uh, for a moment, I was thinking that your were talking about the NSFW bf...

DJMcMayhem

@LeakyNun It means it doesn't change unnecessary values on either stack so that it can be added to a larger program without worrying about side effects

@Dennis yeah, I know it causes confusion but it's easier than typing out brain-flak. I'm on my phone and lazy

Dennis

bfl?

Also means Butterfly Labs, but I don't think that would come up here...

DJMcMayhem

8:01 AM

I guess that works. Really I should have just picked a better name

I'm gonna actually go to bed now, rather than talking about it like I have been for the last two hours

Anonymous

Just call it bflak

Anonymous

If I can be bothered to type out 8 letters for Actually, I'm sure you can manage 5 :)

muddyfish

8:16 AM

I can't be bothered to retype my code, my 4 letter language name or a Try it here link.

Fatalize

I'm suprised no one has yet called a language Flog: it's Golf reversed and the meaning could probably fit the design of some languages…

feersum

There's Flogscript.

Fatalize

@feersum That's almost-golfscript right?

feersum

Probably, but I'm not familiar with it.

New Main Posts

8:34 AM

0

Q: To create a simple equation solver in C++ [A tough one. Simple concept complex code]

Algorithm: Create a C++ program where the user will enter the LHS of any mathematical equation using the variables of his choice.. Like for example: ax+by+c Next ask the user the values of the variables he has defined. In this case a,x,b,y and c. Next substitute the values in equation and ...

code-golf math code-challenge c++

orlp

I just thought of a really cool physical algorithm

let's say you have to repeatedly calculate the shortest path between some set of nodes

you grab some numbered balls

and associate each ball with a node

for each connection between the nodes you connect a piece of string proportional to the cost of that connection

now all you need to do to find the shortest path between two nodes is pull the numbered balls apart until the string is tight

that is your shortest path

Anonymous

Very clever

Adnan

@Dennis Could you please pull 05AB1E?

Anonymous

I like the massively-parallel approach: have a bunch of people walk each possible path. The first person to get to the goal has the shortest path.

Jonathan Allan

Could someone review this? I just noticed the comment I added is not that obvious unless one actually looks at the markdown - there is some text to remove!

codegolf.stackexchange.com/review/suggested-edits/32824

orlp

8:45 AM

@Mego that's what the strings are doing

Anonymous

Or the university campus approach: grow grass on each path and set a bunch of college students loose. Come back in a few months and see which path is worn the most.

Jonathan Allan

OK it's done - thanks @Mego

Fatalize

@Mego This will be biased based on where Pokémon spawn

Anonymous

@JonathanAllan Glad to help :) In the future, if there's not enough to change to make the suggested edit system happy, just leave a comment instead.

Jonathan Allan

@Mego Heh I did, then removed it and thought I'd be clever :p

Anonymous

8:49 AM

@Fatalize My algorithms professor explained that algorithm before PoGO became a thing

orlp

@Mego every string is massively parallel providing pressure

Anonymous

@orlp Yes, I see that. What I said was an alternative way of applying the same strategy.

orlp

a string tightening is like a wave going through connected atoms

New Main Posts

0

Q: What does this button do?

Currently at my work we moved to a new building. It's supposed to be state of the art and has automatic lights, automatic roll-down shutters, and is now known as the most eco-friendly building in this town. However, it doesn't really work all that well.. The roll-down shutters sometimes go down o...

code-golf ascii-art

Anonymous

@JonathanAllan While it was clever, it undermines the point of the suggested edit system a bit. It's best not to do it, or else your editing privileges can get revoked.

Anastasiya-Romanova 秀

8:51 AM

What is the reason this chatroom is named "The Nineteenth Byte"? Is there a relation with this site: servicehostnet.com/domain/19thbyte.com

Jonathan Allan

@Mego Oh, had no idea and am 10K on another stack :/

orlp

no

@Anastasiya-Romanova秀 the nineteenth hole is often the name of a club on a golf location

Anonymous

@Anastasiya-Romanova秀 Nope. The Nineteenth Hole in golf means the closest bar to the golf course, where golfers often congregate after games to drink and chat. We adopted that to The Nineteenth Byte, since our golf is a bit different.

orlp

we are a code golf site

Jonathan Allan

@Mego anyway wont be long to 1K here so I'm sure I'll cope :P

orlp

8:52 AM

so we ahve the nineteenth byte

Jonathan Allan

As in - "See you at the 19th hole for a beer"

Anastasiya-Romanova 秀

I see

Anonymous

The first 18 holes are the holes on the golf course. The 19th hole is the "watering hole" (a slang term for a bar in the US).

Fatalize

33

A: Let's think of a creative name for our chatroom

Well, the traditional generic name for the country club bar is "the nineteenth hole", which suggests The Nineteenth Byte or something like that.

Anastasiya-Romanova 秀

So basically this chatroom is like a bar where people can have fun

Fatalize

8:55 AM

"That name is perfect; it is exactly 19 bytes in size"

Jonathan Allan

@Fatalize heh hadn't noticed that!

Sherlock9

@Anastasiya-Romanova秀 And we have some bar tropes, too. "We don't serve that here." vs. "We don't do your homework or answer question. This is a challenge site not a Q&A site."

Anastasiya-Romanova 秀

@Fatalize I vote for that comment

Sherlock9

No bar fights though. The bouncers here are pretty good at dealing with people who are causing a ruckus

Fatalize

we even have a bartEnder

Anastasiya-Romanova 秀

9:01 AM

@Sherlock9 Luckily there's no bouncer because a 13-yo-kid like me can get rejected entering this bar :D

Anonymous

@Sherlock9 You say that...

Fatalize

@Anastasiya-Romanova秀 You're not the only one here to be 13, I'm pretty sure there are other users of that age

Sherlock9

Well, we did have a 12 year old who was removed until he turned 13

Anastasiya-Romanova 秀

So who else is under 20 here?

Adnan

Aye

Sherlock9

9:03 AM

Oh that reminds me. If you have Discord, @Anastasiya-Romanova秀, come join us: discord.gg/fE3gE

Fatalize

A lot of people

Anonymous

And we did have an even younger person who was banned from chat by our mods (I think) and then subsequently banned from SE because they admitted to lying on the registration form.

Sherlock9

Nope. Turning 21 next month

Fatalize

24 here so I guess I qualify as old in here

Anonymous

22 here

Emigna

9:06 AM

It's not often I get to feel old, but it seems like I'm one of the oldest here (at 31)

Fatalize

@Mego Is that really a problem that someone is not actually >13?

Sherlock9

s/>13/>=13/

Anonymous

@Fatalize SE Terms of Service require you to be at least 13 to register an account

Fatalize

Why?

DerpfacePython

Augh maths proofs are annoying

Fatalize

9:10 AM

Seems pretty arbitrary

DerpfacePython

Can anyone proofread my proof to make sure it's up to scratch?

Fatalize

What proof will you have that we proofread your proof correctly?

DerpfacePython

Ummm... this is the question.

Adnan

@Fatalize I don't think SE can change anything about that

Since it's a legal issue

Fatalize

A legal issue?

Anonymous

9:11 AM

US law. COPPA requires websites to require special forms to be filled out if a user under 13 is to register on the site with any kind of identifying information (including email addresses). A lot of places just disallow people under 13 from registering to avoid the headaches.

DerpfacePython

Find a prime, p, with the property that for some larger prime number, q, both 2q-p and 2q+p are prime numbers. Prove that there is only one such prime p.

I'm older than 13

Marginally

So I'm fine, right?

Adnan

Yep

Fatalize

Would that even apply if the person is not american?

Anonymous

@Fatalize Yes. It applies to websites hosted in the US.

DerpfacePython

@Fatalize To extend on that... is anyone Aussie here?

(It's not really extending, but whatevs)

Fatalize

9:14 AM

Quill is australian

and Sp3000 I think

DerpfacePython

I'm guessing the average age here (in this chat room) is around 20, right?

Anonymous

@DerpfacePython What's your proof?

DerpfacePython

Ummm... do I pastebin it?

Anonymous

A gist would be better

DerpfacePython

It's written, I can take a picture of it and post it here.

Anonymous

9:16 AM

gist.github.com

DerpfacePython

I can go on imgur or smth like that.

Anonymous

Transcribing it would make it much easier to read

Adnan

@DerpfacePython I think the average is about 18-19

DerpfacePython

@Mego But the thing is, it would take me, like 20 minutes.

Fatalize

Should just get a strawpoll running

Adnan

9:17 AM

There already was one: strawpoll.me/10715168/r

Fatalize

There's one vote for 10/13

Hunt him!

Anonymous

@DerpfacePython Well, if none of us can verify it, your next step would be to try over at Math.SE, which would require you to transcribe it anyway.

Sherlock9

Well, let's see the picture first. It may be okay

DerpfacePython

gist.github.com/DerpfacePython/c9cb849278ecaf8eb1ba0588144606f1

I got a gist.

You guys are looking at it, right?

Sherlock9

Looks right

You should probably mention that Part B.II. is a proof by contradiction

DerpfacePython

9:32 AM

Ah.

Sherlock9

Or put "Let us assume that there is a p > 3." somewhere in there

Anonymous

@DerpfacePython Nitpick: the possible remainders from dividing by 6 are 0-5, not 1-6. The logic is still sound, though.

DerpfacePython

Ah, yeah.

Whoops.

@Mego Is there anything else? Or is that basically it?

BTW, this question is from a past paper from the "Australian Intermediate Maths Olympiad".

Anonymous

@DerpfacePython It looks correct to me.

Jonathan Allan

@DerpfacePython p=3, q=5 -> 2*5-3=7; 2*5+3=13. p=3 q=7 -> 2*7-3=11, 7*2+3=17. disproved

Sherlock9

9:35 AM

He's asking for a p other than 3

Jonathan Allan

oh?

missed that :/

DerpfacePython

@JonathanAllan Yeah, I'm asking for a p other than 3. It's up further in chat, so... yeah.

Updated for clarification, just in case anyone else sees it.

I just think the "Scenarios" bit is repetitive.

Anonymous

Yeah, the proof is that p=3, q=5 is the only pair of primes where 2q+p and 2q-p are prime.

DerpfacePython

@Mego q can be anything, it's just that p has to be 3.

@JonathanAllan So... any reviews?

Also, anyone else in chat (but isn't chatting) please give feedback... I desperately need it!

feersum

I would think you only need to consider cases mod 3, not mod 6.

And the special case for 2 could be dropped.

ABcDexter

9:43 AM

print('Hello World!')

DerpfacePython

@feersum I'm mainly basing my proof around the fact that any prime larger than 3 can be either represented as 6p+1 or 6p-1. I'm probs keeping the special case, though, as the proof needs to be "complete".

Notice the "" marks around complete

Anonymous

@DerpfacePython Err yeah that

feersum

@DerpfacePython And similarly, any prime not equal to 3 can be represented as 3m+1 or 3m-1.

Sp3000

@feersum Neat

@Fatalize Just to confirm: yep

@ABcDexter print('Greetings!')

flawr

Jonathan Allan

9:53 AM

@DerpfacePython I think this holds (not my strongest suit): 2q+p and 2q-p prime would have to be congruent to 1 or 5 mod 6 (else they would be even or divisible by 3) but (by Euler) all primes of that form are also of the form x^2+3y^2 so p would need to be congruent to 0 mod 3, which is only true for p=3.

mathworld.wolfram.com/Eulers6nPlus1Theorem.html

@flawr - now I gotta you tube it :D

flawr

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