Mathematics - 2014-12-15 (page 1 of 10)

Mike Miller

12:01 AM

Hats have arrived.

Well, hypothetically; the hat window isn't opening on my end.

teadawg1337

I got a hat!

Oh, it's not opening for me either...

Mike Miller

The only reasonable conclusion to come to here is that StackExchange has unceremoniously cancelled hats, and that we should riot.

Daniel Fischer

@evinda Not necessarily. For something simple consider say $p = 3$, and suppose the array is sorted. If the array has an odd number of elements $2k+1$, the median is at position $k$, and the three elements we want can be A[k-2],A[k-1],A[k] or A[k-1],A[k],A[k+1] or A[k],A[k+1],A[k+2].

evinda

@DanielFischer Yes, but what happens when the array is not sorted?

Daniel Fischer

@evinda We sort the relevant part. That the other parts are not sorted doesn't matter.

Behaviour

12:07 AM

in Tavern on the Meta on Meta Stack Exchange Chat, 48 secs ago, by balpha

@Undo Don't worry :) The only sites that have no hats are MO, TeX, and ja.SO

Robert Cardona

Offtopic question: I'm looking at $p : \widetilde X \to X$ a double cover and the induced map $p_\sharp : C_n(\widetilde X; \mathbb Z_2) \to C_n(X; \mathbb Z_2)$. I know $p_\sharp$ is surjective and each $\sigma$ has exactly two lifts $\widetilde \sigma_1$ and $\widetilde \sigma_2$. Why is $\ker p_\sharp$ generated by $\widetilde \sigma_1 + \widetilde \sigma_2$?

evinda

@DanielFischer At ehich point do we sort the relevant part? :/

Mike Miller

@Behaviour I'll believe him for now, but my profile brings up only a loading screen instead of a list of many hats for me to wear, which by my count is many hats too few.

teadawg1337

@Behaviour I get the hat option, but I cannot see what hat/hats I have earned

Daniel Fischer

@evinda That's the partialQuickSort stuff.

theGuy

12:09 AM

Hi guys

Daniel Fischer

@MikeMiller Perhaps you have not yet earned a hat?

Mike Miller

A disgusting proposition.

theGuy

first time earning chat privelages good to be here !

Daniel Fischer

@MikeMiller I see that you also have Saint Lucia.

teadawg1337

I got a notification saying I earned Saint Lucia on Mathematics, but it's not showing up on my profile

Daniel Fischer

12:10 AM

(And none else so far)

teadawg1337

Well, it is, but I can't see the "inventory"

Daniel Fischer

@teadawg1337 For me, it shows.

Mike Miller

Here's a screenshot of what goes wrong.

Are you using Chrome, @teadawg1337? That's what I'm using.

teadawg1337

@MikeMiller Yes, I'm using Chrome

evinda

@DanielFischer Yes, but then how can we know the interval to which the elements which interest us belong before having sorted them? Can't it happen for example that there is at the first position one of the nearest elements to the median?

Daniel Fischer

12:12 AM

@MikeMiller That explains everything ;)

Mike Miller

Worked fine last year!

Daniel Fischer

@evinda At the start, we have no idea where anything is. That's why we call partialQuickSort, to move the elements we're interested in where they belong.

@MikeMiller Which was approximately 7583 Chrome versions earlier.

Mike Miller

I'm sure those versions did nothing but improve in every way.

evinda

@DanielFischer So, do we sort all the elements from the beginning till the position where the pivot is?

Daniel Fischer

@MikeMiller You're not reading bug reports on meta?

Mike Miller

12:15 AM

Nope.

teadawg1337

Hmm... It's not working for me if I use Internet Explorer, either....

Behaviour

@MikeMiller I'm using Chrome and have no issues with hats. Any errors in the console, Control-Shift-J?

Mike Miller

Aye. "Uncaught TypeError: Cannot read property 'appendTo' of undefined cdn-prom.sstatic.net/WinterBash/js/core.js:2"

teadawg1337

@Behaviour Uncaught TypeError: Cannot read property 'appendTo' of undefined

Daniel Fischer

@evinda No. We find the first pivot. We partition the array. Then we have smaller than pivot, pivot, larger than pivot. Then we look whether we need something from smaller than pivot if we do, recur on that part, else skip. Then we look whether we need something from larger than pivot. If we do, recur on that part, else skip.

teadawg1337

12:17 AM

I'm gonna try Firefox

Behaviour

@MikeMiller I'm so not debugging that. :p

Mike Miller

I can also successfully look at the hat selections of others - but not my own.

@Behaviour Is this worth taking to meta.SE, you think?

Behaviour

@MikeMiller You can post a bug report on meta.math too, I think we have a tag for those.

Maybe it's specific to your account here.

Mike Miller

I also for some reason have a hat on Meta.SE, and it's not working there.

(No hats on my other sites.)

usukidoll

anyone know how to export latex files to pdf?

Forever Mozart

12:20 AM

yes

usukidoll

how?

Forever Mozart

download this, import your latex file, then export to pdf lyx.org

usukidoll

hmm which one should I download? I got the latex program already

Daniel Fischer

@usukidoll Maybe you have pdflatex installed?

Which OS?

usukidoll

errr?

I'm in Windows 7 and I use texmaker

Forever Mozart

12:22 AM

Oh, well I use LYX for everything.

teadawg1337

lol, Firefox isn't keeping me logged into the main...

usukidoll

Installer: LyX-2.1.2-Installer-1.exe (~35 MB)
Download this one if you already have an older version of LyX installed and you want to update it. This installer requires that LaTeX (MikTeX or TeXLive) already be installed. ????????????

meh I'll just install the bundle

teadawg1337

I'm sticking to Chrome, I hate the UI on other browsers

Daniel Fischer

@usukidoll I think texmaker should have the option to produce pdf output. I don't know where you'd find it though.

Forever Mozart

ok I think you will like it. LYX displays your math code immediately on your screen, and it is also easy to find special symbols using it

Mike Miller

12:24 AM

Posted the bug report here.

evinda

@DanielFischer So do the following commands have to be executed, after having found q?

if (q-1>=low) partialQuicksort(A,left,q-1)
if (q+1<=high) partialQuicksort(A,q+1,high)

usukidoll

@DanielFischer found it! It's f6 to export to pdf

Daniel Fischer

@evinda Yes. I'd write the conditions as q > low and q < high, though.

usukidoll

The proofs I got in my notebook are too long to rewrite so I type them instead :P

Forever Mozart

I use LYX so that I can see the symbols instead of the latex code on my screen

evinda

12:26 AM

@DanielFischer A ok...And why do we have to use a new function partialQuicksort and we cannot use the function Quicksort and change the parameters?

Forever Mozart

it also is easy to adjust document settings with LYX

Daniel Fischer

@evinda Not quite, I sense a typo. You call with high in the second, that should be right (where left and right are the arguments you got on the parent call).

evinda

@DanielFischer Yes, that was a typo... Sorry!!!

Daniel Fischer

@evinda Call the entire thing partialQuicksort. Calling it quicksort would be a lie, since it doesn't sort the whole array. Function names that lie about what the function does are evil.

Bad function names are merely bad. Lying function names are evil.

Forever Mozart

time to watch Glengarry GlenRoss

usukidoll

12:29 AM

hats?

Mike Miller

Hats!

Hats... :(

where u get it?

Hats off gentlemen!

I don't, apparently.

I am stuck

I cannot solve this problem

I guess there is a reason it is unsolved...

:( so depressing...

evinda

12:33 AM

@DanielFischer So now we have two subarrys and the pivot of the subarrys will be the median element of the subarray and at the positions before that we will have the smaller elements and at the positions that are after that the greater ones.. Or am I wrong?

Daniel Fischer

@evinda You are (probably) wrong about "the pivot ... will be the median ...". That's unlikely to happen, but when choosing the pivot per median-of-medians, we are guaranteed to have a pivot not too far away from the median (of the subarray). The rest is right.

teadawg1337

@MikeMiller balpha is working on it :D

Mike Miller

Yeah. I'm impressed how quickly it was reproduced. Maybe the solution is "update your Chrome".

teadawg1337

Nope, I'm running the most up-to-date version on Windows 8.1

Daniel Fischer

@MikeMiller Usually, the solution is "it worked with the previous Chrome version".

Forever Mozart

12:37 AM

wet out there to night

Mike Miller

@DanielFischer I won't take this Chrome sass much longer before we have to fight for the death for its honor.

Forever Mozart

I have used firefox for years

Daniel Fischer

@MikeMiller I'm not saying Chrome is bad. But it's a fast-moving target. Too fast often.

Forever Mozart

Is Chrome available on Linux?

Mike Miller

Probably so. I haven't updated it in a long time, and only do so sporadically. I also suspect its performance is worse than Firefox. I just vastly prefer the UI.

Daniel Fischer

12:39 AM

@ForeverMozart Sure. Want to try it?

Forever Mozart

no I am happy with firefox, just curious

Daniel Fischer

@MikeMiller If you haven't updated it for long, it could also be "version too old" for you. That would be rare for a Chrome bug, however.

evinda

@DanielFischer And then do we know that the p closest elements to the median element cannot be at a position before the position at which the new pivot belongs ? Or am I wrong?

Forever Mozart

Good grief I got a nasty email from one of my students :(

you can't make everyone happy

usukidoll

oooooooo what does it say

Mike Miller

12:42 AM

Ah, I just earned another mysterious hat.

teadawg1337

@usukidoll I'm pretty sure it's not of your concern, but I may be mistaken

Daniel Fischer

@evinda That depends. If $p$ is large, we probably need a few more rounds of recurring in both subarrays. But, whatever $p$ is, after some time, we can skip one of the recursive calls.

usukidoll

@teadawg1337 humph

teadawg1337

@usukidoll Bah humbug.

Forever Mozart

just the usual complaints you get when you fail a student @usukidoll

usukidoll

12:43 AM

Forever Mozart

lol what is with you and that cat?

evinda

@DanielFischer Oh yes, right!!! But after the recursive calls, how can we know the positions that correspond to the interval that the p closest elements to the median element could belong? Don't do we have to store them at a variable?

Daniel Fischer

@evinda Either store them as global variables or, better (because cleaner) pass them as arguments to the partial sorting function.

Forever Mozart

I am going to have to fire my secretary

evinda

@DanielFischer Will this position be equal to partialQuicksort(A,p,r)+1 ? Or am I wrong?

teadawg1337

12:49 AM

Style

Eeek, noooo.... It's slightly off-center....

Forever Mozart

►

Mike Miller

Oh, cool, our hats show up in chat now.

skullpatrol

only along the LHS

Alexander Gruber

Is Santa Lucia the only one out now? :)

Oh no you've got soccer

Mike Miller

Nope, I've got three.

Take a look at my sick soccer ball hat.

Alexander Gruber

12:51 AM

That's pretty dope.

teadawg1337

There, this looks better

Mike Miller

Oh sick, they finally added favorite tags to the iOS app. Now I have a reason to use it.

Forever Mozart

what is with the hats???

Alexander Gruber

@MikeMiller Is that for awakening your hidden potential?

skullpatrol

@ForeverMozart go to your profile and click on the snowflake at the top

Mike Miller

12:53 AM

Perhaps so, @Alex, because I awakened it long ago.

I really want the Bill Lumbergh hat.

AWertheim

The Bill Lumbergh hat?

Mike Miller

There's a complete list of non-secret hats here

5

AWertheim

Ah, thanks. Love it.

I wonder if you get two Bill Lumbergh's stacked on top of each other if you answer 5 questions on Sunday as well..

Mike Miller

Doubt it. :P

evinda

@DanielFischer I have to go to sleep now.. I will be on again tomorrow... Good night!!!

Alexander Gruber

12:56 AM

@MikeMiller I'm gonna have to put Kwanza in my calendar

Mike Miller

Some of these hats I'm never going to get on principle.

AWertheim

Who really wants "resolution"?

teadawg1337

Crab people

Forever Mozart

teadawg1337

@ForeverMozart Rock Lobster?

Forever Mozart

1:08 AM

yes

teadawg1337

Biggest WTF post of the day.

Mike Miller

@Behaviour I seem to have gotten Redshirt before you. Scandalous!

usukidoll

what the!

there is no way that negative infinity = infinity nuh uh

doesn't make sense

just like heat contained = heat escaping... are you serious?

Behaviour

@MikeMiller No worries; I'll get it. Glad to see there are two hats for downvoting.

Though it'd be nice to have more than one for editing.

teadawg1337

@Behaviour You look fashionable as a crab person ;)

Mike Miller

1:16 AM

The question is poorly worded, but I agree with Alex's comment that it could (and probably will) inspire a good answer.

usukidoll

ooo I want a hat

Mike Miller

@Behaviour Always recall there were secret hats last year. No reason to believe the same isn't true this year.

usukidoll

@teadawg1337 how did you get the crab hat? looks cute

Mike Miller

By downvoting garbage.

teadawg1337

Which there is A LOT of today

Mike Miller

1:18 AM

And yesterday. Tomorrow, too.

teadawg1337

Hello @Jasper

Jasper Loy

@teadawg1337 Hi, I see you have a hat.

teadawg1337

@Jasper Indeed I do

Looks like the Redshirt "hat" is just beyond reach

Behaviour

@MikeMiller There will be secret hats for sure (some people have them already). But being secret, they do not do much to encourage a particular course of action.

Mike Miller

@AlexanderGruber I modified the tags on the circle question a bit. I'm sure it could use some more, though.

skullpatrol

1:34 AM

there is another pde specialist there now @usukidoll ;-)

Jasper Loy

@skullpatrol Where is there?

skullpatrol

@JasperLoy the physics chat room

Behaviour

@MikeMiller For example, Logan has three secret hats already.

skullpatrol

he must be a spy

Mike Miller

Very mysterious!

Jasper Loy

1:44 AM

I tell you the truth, this hats thing will drive you all mad for hats soon.

skullpatrol

every year they have it is the same

usukidoll

@skullpatrol where is the pde specialist?

Mike Miller

6 mins ago, by skullpatrol

@JasperLoy the physics chat room

teadawg1337

@usukidoll Not here

Behaviour

But not unexpected, given that Logan was last year's network-wide winner.

usukidoll

1:49 AM

@teadawg1337 where did you get the crab hat

skullpatrol

@usukidoll Kyle Kanos

teadawg1337

@usukidoll I got it for downvoting five crappy posts

usukidoll

@teadawg1337 nice time for some crappy post treasure to hunt

teadawg1337

@usukidoll Not too hard to find these days

skullpatrol

@usukidoll ask him nicely

usukidoll

1:52 AM

there's a hen in my yard...again

teadawg1337

@skullpatrol The question was phrased just fine

usukidoll

math.stackexchange.com/questions/1068510/… wow dat negative numbah

teadawg1337

I was the first to downvote that post, and the first to flag (I think) :3

Mike Miller

I wonder how much more common downvoting will be given the hats.

Perhaps the season will bring out everyone's inner downvoter, and it'll stay out after the hats go home.

skullpatrol

the darker-side of Xmas

Behaviour

1:54 AM

@MikeMiller I'm pretty sure this is intentional on the part of SE. The community team had some input into what actions should be hat-encouraged...

Mike Miller

@Behaviour Related: what's the correct course of action when a user reposts a highly downvoted closed question with minor changes as a new question? Do the same, or flag for mod?

Behaviour

@MikeMiller I would vote to close. Either for the same reason as before, or as a duplicate.

teadawg1337

Wait, I flubbed up that flag.....

Oh, nvm. I did just fine

Behaviour

If the continue at it, they'll face question ban / rate limit pretty soon.

skullpatrol

@teadawg1337 How is "do you know pdes?" phrased nicely?

Alexander Gruber

1:57 AM

@MikeMiller Yeah your projective geometry tag is better too

Gosh, I'm riled up.

usukidoll

oh yeah got my hat @teadawg1337

teadawg1337

@skullpatrol Oh, I thought you meant the question directed towards me about the crab hat

Alexander Gruber

I don't blame you for closing it at all (I had to do a double take myself) but there are some deleted comments there that are pretty mean

teadawg1337

@usukidoll Yay :D
Craaaaaaaaaab people

usukidoll

so is there any other hats to earn? Is there a complete list @teadawg1337

Mike Miller

1:58 AM

There's a complete list of non-secret hats on the link starred to the right.

teadawg1337

@usukidoll winterbash2014.stackexchange.com

usukidoll

@teadawg1337 fits well too! :D

Jasper Loy

Nobody earns all the hats.

skullpatrol

that ^ is the hook

ok, if you say so pal :-)

teadawg1337

@skullpatrol It's not a scam if I enjoy it! Oh, wait...

usukidoll

2:00 AM

Mistletoe
post a chat message within five minutes of 0 UTC 1/1/2015 that gets starred

Sumo Judge
give stars to 8 users in chat

Venus

This hat looks funny. I want to collect them as many as I can ^^

usukidoll

:D!

Alexander Gruber

Hey there starrypants

Jasper Loy

Someone is starring everything, lol.

Alexander Gruber

You wanna knock that off

Studentmath

2:01 AM

Woha, that's a lot of starrs..

Jasper Loy

AFAIK, no mod stops people from starring.

Studentmath

And there I was trying to get to something Mike said and it disappeared before I was able to click on it..

Alexander Gruber

@JasperLoy i'll remove stars sometimes if I feel like somebody's spamming the star queue for no reason

Mike Miller

@AlexanderGruber like now, mayhap?

Behaviour

@AlexanderGruber But there's a reason now! Haaaats.

usukidoll

2:02 AM

aww but I just want a hat

Alexander Gruber

Oh damn it is there a hat for starring

skullpatrol

@JasperLoy there must be a hat for starring

teadawg1337

O_o

Mike Miller

I'm sure you'll find plenty of inspiring messages over the next couple weeks, @usukidoll. No need to star so much right now.

usukidoll

Sumo Judge
give stars to 8 users in chat

Jasper Loy

2:02 AM

@skullpatrol Maybe there is a mod hat for unstarring.

Alexander Gruber

@JasperLoy LETS FIND OUT.

skullpatrol

yes

Studentmath

Welcome back @Jasper

Jasper Loy

@Studentmath Hi! Have you done your exams?

skullpatrol

19 mins ago, by Jasper Loy

I tell you the truth, this hats thing will drive you all mad for hats soon.

teadawg1337

2:04 AM

I'm already cuckoo for Cocoa Puffs! I mean hats!

Studentmath

@Alexander "unstar all the starred masseges in a chat from january 2014"

@Jasper 4 left and I'm done

usukidoll

@studentmath unstar starred messages in chat from 1/2014?

Venus

Why there's no hat that looks like cop's hat? I like that kind of hat, makes me look powerful

skullpatrol

you like power?

teadawg1337

There's a less annoying way to spam-star messages: the pre-starred ones to the right. Not that I'm encouraging the act of spamming stars

Alexander Gruber

2:06 AM

@Venus make one yourself man

Venus

Yep

Nah. Girl with cop's hat looks more cool. I love taking control

usukidoll

here's something to look for in downvoting for this shirt?!

Red Shirt
cast 5 downvotes on posts that are later deleted or closed

Mike Miller

Look for PSQs where the OP clearly copies a homework exercise and makes no effort whatsoever to do the problem. Downvote them. Continue doing this after your five downvotes, and indeed after the Holiday Bash ends.

Alexander Gruber

(WB hat list) If you just want Sumo Judge, please add stars to these, not random posts.

36

Mike Miller

@AlexanderGruber You should either unsticky my message or yours. It's pretty clogged.

Alexander Gruber

2:10 AM

hmm

Forever Mozart

Bath time

Mike Miller

I can only see one non-stickied message right now on my puny screen.

Alexander Gruber

@MikeMiller how wide is the star queue on your screen?

where does my message hit a new line?

Mike Miller

@Alex

teadawg1337

...

Forever Mozart

2:12 AM

hat?

Mike Miller

I'm on a 1366 x 768 laptop, which is probably not entirely unusual.

Forever Mozart

my hat is not showing

Alexander Gruber

@MikeMiller yeah, it's better than mine.

Forever Mozart

hat?

teadawg1337

I have a 1920x1080 laptop, lol

Mike Miller

2:13 AM

Anyway, I say you get rid of mine. I've faith people can find the hat list on their own if they really want to see it.

Forever Mozart

where is my hat?

Alexander Gruber

@MikeMiller I'll just combine them. I'm just calculating some width stuff to try to make it as few lines as possible.

Mike Miller

Don't star random stuff for hats. Full list here.

teadawg1337

@ForeverMozart It doesn't show up immediately in chat, I found it takes about 2-3 minutes and a few page refreshes to update

Alexander Gruber

How bout that? ->

Mike Miller

2:22 AM

i'll allow it.

@Behaviour Can you guess why this question is getting 'unclear what you're asking' votes?

Behaviour

@MikeMiller Don't know, perhaps the boundary between what the OP knows and does not know was not drawn clearly enough. I hope the edit helped a bit.

Although without knowing their definition of simply-connected, it's not easy to help.

teadawg1337

Holy crap, I already have four hats

5

Mike Miller

Their "squeezed to a point" comment leads me to believe it's the $\pi_1 = 0$ one.

Behaviour

@MikeMiller Or contractible, which is equivalent but would have a different wording of the proof.

Mike Miller

Right.

Behaviour

2:28 AM

Boo, the "I voted today" hat is U.S.-themed. I'm not a U.S. citizen, so...

Mike Miller

Though I would probably show that $\pi_1 = 0$ by showing it's contractible, so...

skullpatrol

you're not?

teadawg1337

I. Got. A. Secret. Hat.

skullpatrol

Do. You. Got. A. Secret?

Mike Miller

hmph

usukidoll

2:36 AM

Maybe.I do. Maybe. I . Don't.

skullpatrol

:D

Daniel Fischer

Not quite :(

Mike Miller

@DanielFischer I saw that!

teadawg1337

What did it say?

Daniel Fischer

@MikeMiller Yes, but I saw it before you ;)

Mike Miller

2:37 AM

@teadawg1337 You'll never know.

skullpatrol

It said "Merry Xmas"

Daniel Fischer

@skullpatrol Wrong religion.

Happy Holidays?

Happy Hanukkah

icic

2:39 AM

If anything

Forever Mozart

hat?

oh yeAH!!!!!!

HAT!!!

skullpatrol

:O

teadawg1337

I think I know how this hat is earned as well, but I'm not telling :3

skullpatrol

9 mins ago, by skullpatrol

Do. You. Got. A. Secret?

So. You. Do.

:D

Forever Mozart

my hat was earned by upvoting someone I think :D

its a cheap hat

actually its a candelabra

bunch of candles melting on my head

teadawg1337

2:51 AM

I think this one has to do with [redacted], but I'm not sure

:P

Forever Mozart

what is it?

a bunny wabbit?

teadawg1337

@ForeverMozart It has to do with doing [redacted] within [redacted]

Forever Mozart

whaaaaaaaaat???

Behaviour

Comment template: "Welcome to Math.SE! You picked a bad time to dump your homework here: the users are trying to earn Imitation Crab and Red Shirt hats."

6

teadawg1337

"Imitation Crab" was a smart title for the hat

skullpatrol

2:58 AM

who wants to imitate a crab?

Forever Mozart

if only I could solve one unsolved problem

then I would not feel like a failure

Transcript for

$Mathematics$ Mathematics