CRPxTumblr - 2015-07-10 (page 1 of 2)

Eric Stucky

04:07

She (?) has been posting a lot of stuff recenty about an upcoming IBL MOOC course in precalc. I was just wondering if you had any thoughts about it, since you were nominally in chat when I sent that :)

Sami Brooker

yeah, i think she.

and i saw that! it sounds potentially interesting but idk?

i was thinking of telling my mom about it because she's currently taking a trigonometry class and i thought she might find some other resources helpful, but i don't want to overwhelm her lol

Eric Stucky

wow what prompeted that?

req for grad?

Sami Brooker

hm?

Eric Stucky

your mom's trig class

Sami Brooker

oh, yeah! she's going back for her AA and apparently she managed to avoid taking any math classes on the first go around at college so now she's paying her dues

Eric Stucky

04:20

:P

Sami Brooker

i mean, in reality i am the one paying her dues because i've become her personal live-in calculator

Eric Stucky

well, same difference :P

Sami Brooker

yeah, it skips a generation or something like that

Eric Stucky

Is this your usual schedule? Casual MSE chat at 12:30a?

Sami Brooker

it's 9:30 my time, and i thought it was only 11:30 your time? you're in MN, right?

Eric Stucky

04:30

Oh, my records are wrong then XD I thought you were East coast

But eyeah I am in MN now

We should maybe make a more useful timezone star

Sami Brooker

i have to agree with that

i find it much easier to remember what, like, region people are in, and then just google the time there if i don't already know what the difference is between there and wherever i am

Eric Stucky

Alex +10 // Eric -6 // Jordi -7 // Sami -4

2

Can you star that?

Hooray :)

Sami Brooker

go team

did you get my update email today? i'm not sure i sent it to the right address :P

Eric Stucky

you didn't but I did :P

Sami Brooker

aaaaaah okay

Eric Stucky

04:33

I already have a response written up so I might as well just send that

but

about the youtube thing

I considered being more aggressive about that in Week 3 and I decided against it

I still think it would be really useful and fun

but it occurs to me that it's actually a huge timesink

Sami Brooker

yeah, i feel that

Eric Stucky

So that tears me up a little

I think we should just ask the rest of the group tbh

Sami Brooker

fersure

Eric Stucky

Wowo so I'm about to teach probability tomorrow and suddenly this post.

Sami Brooker

?

Eric Stucky

04:38

I mean, that's the classic example right?

we are bad at probability look people bet against their history

but apparently

maybe that's correct?

Sami Brooker

ahh i feel like i'm missing a lot of what's going on in that post

which tends to be the case for me with jadagul's posts in general

Eric Stucky

XD

I'm getting increasingly sketched out by it but it seems like the point is that TH is a more likely event in a string than HH

this is obviously not true but

Sami Brooker

???? what the heck

Eric Stucky

subject to some mild conditions, it seems?

Sami Brooker

that's wild

Eric Stucky

04:44

Ah, okay this makes more sense:

(at least, it's not obviously completely wrong)

The expected number of THs in a string is higher than the expected number of HHs.

Anyway this has been most of my day

Distracted by probability and fibonacci numbers

Sami Brooker

right, yeah, business as usual

my fave TA emailed me to tell me to work through a couple sections of a book for some "summer reading" because he thought i must be bored

and not at all completely overwhelmed lol

Eric Stucky

XD

Sami Brooker

isn't that sweet of him

Eric Stucky

<3

You should send him some of our papers with a similar note :P

Sami Brooker

oh my god

i mean, he has a tendency to chat with undergrads when he is totally slacking on his research so i'm sure he'd appreciate that

Eric Stucky

04:53

haha, good.

I understand that though this is totally how I play sc XD

It's just like, eh, I don't really want to practice

I'll just talk to some bronze leaguers about how they should build workers

Sami Brooker

so i don't know anything at all about starcraft

i mean feel free to talk about it but just know that i don't really have any context lol :P

Eric Stucky

yeah yeah just like math you get used to doing that

Sami Brooker

hahahahaha

user147690

05:23

I'm so sad that I just woke up and it's 3:23pm... and I went to bed at like 12:01am...

Sami Brooker

oh no! did you have anything pressing to do today?

user147690

Nah I guess not haha, just study. But now my sleep patterns are truly ruined again

user147690

I usually like to get up at 6am lmao

Sami Brooker

ahh well maybe that's the problem :P

user147690

Hahaha. Usually I have always had people wake me up, since I can't seem to wake up by alarm, but my ex-gf had to leave at 4am to get testing done for her thesis(she's a mining engineer)

user147690

05:29

Are you happier with Polyhedral cones now @Sami?

Sami Brooker

haha, yeah a little

still working on fans but y'know, baby steps

user147690

What about polyhedral fans, I haven't got to think about Eric's message yet since I just woke up

user147690

So a fan is just a set of cones, such that the cones share a face? @EricStucky?

user147690

@EricStucky Yep that sounds good

user147690

@EricStucky So I am using the definition http://alexpclark.com/index.php?title=Polyhedral_fan, and the first condition looks to me like it simply comes from having the cones in the set, since the cones should come with their faces right.

The second condition looks like it just wants them to share a face, which includes our half lines you said above

Eric Stucky

05:52

Well the thig about the first condition is

that the fan is not a subset of R^n

Rather it's a set of cones

so the first condition is just saying "the faces are real in R^n, so let's make sure they're real in the fan, too"

second condition looks about right

feels like you could have said that simpler tho

maybe something else is happening

user147690

What is the exact definition you are using?

Eric Stucky

Yours

user147690

Oh okay, awesome

user147690

I think I am fully happy with cones, so it should only take a bit of time drawing and thinking to be fully happy with fans

user147690

Well I guess I am not fully happy with cones yet actually, I think I was having some problems with $\Bbb R^4$ yesterday. Anyway I'll go and think more, and come back when I have reached a dilemma, or people want to chat xD

Eric Stucky

05:58

lsounds good :)

Eric Stucky

18:53

heya @Sami

Sami Brooker

19:41

oh hey! sorry, i popped in and out

Eric Stucky

nbd

bleh I am trying to find this study that showed that students who are told they are smart will seek out easy tasks and students who are told they work hard will seek out challenging tasks

but it turns out

if you google "smart students easy hard test study"

you get lots of "21 tips for how to ace your next exam!" type pages

Sami Brooker

ahhh yeah

hmm, lemme know if you do manage to find that study though, that's pretty interesting

also, me as hell

Eric Stucky

XD

I vaguely remember it being in a book something about "the inverse power of praise"

hmm

yessss

somewhere in that article

I am pretty sure

Sami Brooker

jfc the top one percent of kindergarteners

oooookay

Eric Stucky

XD

yep its on the first page

Carol Dweck

Presumably the references here are the relevant scholarly sources

Sami Brooker

19:49

ahhh nice

oh man, this article is too real

Eric Stucky

yeah

our physics teacher was a big believer in involving his students in pedagogy

we read that in the first week of class

It made an impression :P

Sami Brooker

oh fuck, that's awesome

Eric Stucky

Any luck with cones and fans?

Sami Brooker

not really :/

i feel like i don't even know what i'm looking for

Eric Stucky

Iunno when I get to these definitions my goal is just to be comfortable

For me that usually means lots of examples

Hmm I guess I skipped a step

I think you should be looking for understanding the definitions :P

but I think you knew that

Sami Brooker

19:56

which definitions?

or rather, the definitions where?

Eric Stucky

XD yeah unf the paper is just like "oh y'all know what fans are right, cool"

Alex's wiki

has definitions

Sami Brooker

got it ok

how does your lil avatar keep changing???

Eric Stucky

I don't know

Sami Brooker

i feel like everyone else's has been p much the same since the start

Eric Stucky

I wish it would stop tbh

Sami Brooker

19:57

i mean i literally just watched it happen, what could possibly

Eric Stucky

It used to be constant until about five months ago

Sami Brooker

nuts

Eric Stucky

But yeah actually I think it's more specific than that. When I generate examples, the first thing I do is think of the first thing. Then I try to think of the simplest thing. After that it's: non-thing, more subtle non-thing, weird-looking thing (this takes the longest), and applicable thing. No particular order on those last 4.

Sami Brooker

okay can you give me a concrete example where you replace the word "thing" with a thing? i'm not sure i toootally understand what you're saying

Eric Stucky

yeah

so like groups

groups?

that familiar?

Sami Brooker

20:00

uhhhhh

sure

Eric Stucky

eh I'd rather have a more solid response than that

:P

how about linear transformations?

Sami Brooker

mmm, that's worse, sorry

Eric Stucky

mkai

differentiable?

Sami Brooker

yeah, okay

Eric Stucky

okay so the first thing is like: $x^2$ is definitely differentiable

the simplest thing is more like

(hmm kind of hard for differentiablity actually)

maybe a constant function?

I want to say "a function defined on one point" but I don't think

hmmm

well okay I will think about that

non thing would be like $|x|$

more subtle non-thing would be like... some function with rationals idk

not terribly subtle

hmm maybe $\sin 1/x$

weird looking thing would definitely be $\sin 1/x$

Sami Brooker

20:05

ok, so it's basically, like, a "what's an example of what i'm talking about? what's a non-example? what looks like it would work but doesn't, and what looks like it wouldn't work but does?"

that kinda game?

Eric Stucky

yeah

Sami Brooker

ahhhh okay sure i feel that

Eric Stucky

the idea is to sort of poke at the boundaries, too

Sami Brooker

yeah, ok, i do that too then

Eric Stucky

Like the differentiablity of a one-point function... that's weird.

Sami Brooker

20:07

i wish more professors would include that thinking in the way they teach but it's one of those things you can do outside of class

though it's tricky when you can't actually tell if something works or doesn't, i mean, it's certainly helpful to get feedback

Eric Stucky

Yeah afaik it's just a time calculation for in-class things. If you don't go whole-hog on flipping the class there just isn't enough time to both cover the material and provide a rigorous intuitive landscape

Sami Brooker

yeah, i feel that

Eric Stucky

(of course you can still provide a non-rigorous intuitive landscape)

Sami Brooker

it's just a balance, i think

Eric Stucky

ye

Sami Brooker

20:09

y'know, settling for intuitive ideas that aren't rigorously defined to save time, without getting so sloppy that not everyone in the room has the same idea in their heads

i feel like that was the real trick to mathematical logic, but it helped that there were only six students lol

Eric Stucky

:P

Sami Brooker

it was very hard to find people to talk to about that class! i had two friends in the class and both of them were taking other math classes at the same time so they weren't often available, and basically only two grad students in the department knew anything about the subject so i couldn't just ask anyone who walked in the room about it

Eric Stucky

haha yes

a lot of upper div math is that way but logic is particularly brutal

Sami Brooker

i'm just constantly in shock that i took that class

Eric Stucky

XD

Sami Brooker

20:12

like, who let me do that, why did they let me do that

Eric Stucky

I know that feeling

Sami Brooker

shit's ridiculous

Eric Stucky

(I think one-point functions are differentiable)

Sami Brooker

really?

hmm

Eric Stucky

beacuse it's all about that limit, right?

Sami Brooker

20:14

suuuuuure, but

how do you even

like

approach?

Eric Stucky

:P

I think choosing epsilon and delta arbitrary makes the condition satisfy vacuously

because

you need something about epsilon FOR ALL $0<|x-a|<\delta$

but there are no $x$ that satisfy that

so

you're good

Sami Brooker

ahhhh okay that seems

hmm

well, cheap

but that's not a bad thing

Eric Stucky

:P

Kind of useless because all the theorems are "let $f$ be continuous on [a,b] and differentiable on (a,b)" but...

Sami Brooker

right, yeah

Eric Stucky

I'll take it as an explanation for the mismatch

Sami Brooker

20:17

mismatch?

Eric Stucky

[] vs () in the theorem statements

wow that was typo

Sami Brooker

ooh, have you ever seen someone do, like, ]a, b[ for open intervals?

Eric Stucky

haha yes

I wish I hated it less

it's a good notation

Sami Brooker

lol

"i wish i hated it less" is a great sentence

Eric Stucky

:P

Sami Brooker

20:19

i mean, it's kinda gross looking and i wonder if i'll ever be able to write/type it in one try

like without doing inside-right brackets first

(inside-right as opposed to inside-out? i guess)

(not sure where that phrasing came from)

Eric Stucky

XD

Do you read SMBC?

Sami Brooker

i have on occasion but i haven't kept up with it in a couple years, why?

Eric Stucky

haha its pretty tangential, just my gut reaction to the analysis there was "inside-left" and I was having an smbc-esque extrapolation.

Sami Brooker

ah haha

Eric Stucky

I worry maybe a little too much whether my personal vocabulary is comprehensible.

College f***d me up, man

Sami Brooker

20:23

oh no is that a bad thing?

Eric Stucky

haha I don't think so

Sami Brooker

well, then there ya go!

Eric Stucky

It prevents me from saying hukkk to people as a greeting

which

I definitely did earlier today

Sami Brooker

oh, my

well i mean, y'know, live and learn :P

Eric Stucky

haha I guess

so this is kind of a whiplash but

linear transformations

?

more comfortable with groups?

Sami Brooker

20:25

ahhhh my linear algebra class was maybe kind of a sham lol

Eric Stucky

:(

Sami Brooker

i mean, it wasn't bad, it was just not very well-structured so we spent way too much time on calculation-y stuff and basically no time on what should have been the crux of the course

what was, in fact, the crux of the course in the other section that my friend was in

Eric Stucky

ahyeah

I took intro linal just an obscene number of times, so even though most of them were bad like that

I eventually figured it out

Sami Brooker

fortunately my advisor kinda knew that was going on and made sure i had /some/ idea of it, and one of his phd students was the TA for the class so he also did what he could to help

but yeah, the professor was new

and i think maybe she just, like, miscalculated her schedule

10 weeks is not a helluva lotta time

Eric Stucky

yeap

I mean I ask because like

linear transformations

you're going to want them

Sami Brooker

20:29

i knooooow ugh

it's a mess

i'm gonna have to find time to figure that out on my own but i don't know when

Eric Stucky

is this a thing where you're uncomfortable with some concepts; or you don't really know where your gaps are?

Sami Brooker

i don't really know?

sorry, that's unhelpful

Eric Stucky

:P

What do you mean by that

Sami Brooker

i mean, we basically didn't study them at all

that's like, a couple chapters in the textbook that i never read

Eric Stucky

which book

Sami Brooker

20:32

i think i understand the idea of a matrix as like, an operation that you can apply to stuff to do other stuff

Eric Stucky

(braces for answer)

Sami Brooker

umm hang on lemme find it

elementary linear algebra with applications, kolman and hill

Eric Stucky

(that is a hell of a cover)

anyway go on

Sami Brooker

haha

ummm yeah, okay, like, my advisor helped me/made me do some stuff for a javascript project with the rotation matrix?

does that... mean anything?

i hope i'm being clear as day when i say that i have no idea about this stuff

so i mean, it's one of those things where like, i'm aware that this is a thing that exists and i've heard people talk about it, but i haven't the vocabulary with which to talk about it at all

Eric Stucky

(oh jfc this book is a nightmare)

umm

okay

yes, that makes sense

Sami Brooker

20:37

oh noooo

ok, book recs?

for when i ever get around to this

Eric Stucky

haha well

linear algebra done right

is obvious one

Sami Brooker

oh haha i have that

it's around here somewhere

Eric Stucky

it's opinionated af but it's pretty good, honestly

Sami Brooker

it's opinionated???

Eric Stucky

holy shit yes

Sami Brooker

20:38

that's fabulous

Eric Stucky

like it's not as overt about it as other books I've read

but like

if you know what the general story is

you can clearly see him saying "nah this is bullshit"

"you can learn that somewhere else"

Sami Brooker

what do you mean?

Eric Stucky

so the glaring example is determinants

that s the one that catches people's attention

but also

absolutely no complexification: real matrices are done with real methods, end of story

no LU decomposition at all

Sami Brooker

LU?

Eric Stucky

Yeah it's a thing

it's

the formalization of Gaussian elimination

Sami Brooker

20:41

ok

Eric Stucky

Also, transposes are for squares

he introduces adjoints abstractly

Sami Brooker

okay

brb but keep talkin if you have more wisdom to impart

Eric Stucky

mkai I'm probably going to shut up abot Axler tho

When I talk to people on MSE I always reccommend

joshua.smcvt.edu/linearalgebra/book.pdf

it's not great but it's free

hmm I wonder what Alex was doing for linal

haha he was also using Axler

Sami Brooker

ahhhh jeez i definitely need to get around to this stuff at some point

i mean, i was supposed to take advanced linear last quarter rather than math log but i'm kind of glad i didn't because i don't think i had the necessary background

Eric Stucky

o.O I feel like we don't have the same terminology

Sami Brooker

20:48

hm?

Eric Stucky

Is Adv. lin al right after the course you were in?

no other prereq?

Sami Brooker

i think mathematical reasoning and proof (MRP) is a suggested prereq

Eric Stucky

haha okay

Sami Brooker

i mean, it's all political and i think the department hates that they aren't letting that be a hard requirement

Eric Stucky

At my school the "Adv. lin al" course requires Analysis, and it's not like a "mathematical maturity" requirement, it's because you need to know analysis to make any sense of that class.

Sami Brooker

20:50

oh, huh

as far as i know ours is just about, like, provin' stuff?

Eric Stucky

yeah that seems respectable

Sami Brooker

they treat it as a fake prereq for abstract algebra

for the mathematical maturity reason

Eric Stucky

:P

Sami Brooker

so i mean, here's hoping i make it through that

Eric Stucky

haha well

My guess is

errrrr

I was going to say "the beginning will be awkward because examples come from linal"

but

if you use Artin's Algebra

Then you would need to actually get on that.

Sami Brooker

20:53

what, the linear algebra stuff?

shit

Eric Stucky

yeah

He does vector spaces before rings, which is... a choice

Sami Brooker

ahhh come on that sucks

jeez

Eric Stucky

I mean

you should

use Dummit and Foote

but professors gotta be special sometimes

Sami Brooker

hmmm

out of curiosity, how do you end up being familiar with several textbooks on the same subject?

Eric Stucky

Time

Sami Brooker

20:55

i mean, do you just seek them out?

Eric Stucky

Well, okay, the answer is a little more nuanced than that

Sami Brooker

i kinda thought it might be

Eric Stucky

I took a lot of math in HS

which I didn't really understand

Sami Brooker

ohh okay

how much?

Eric Stucky

up to Ranal and Aalg

Sami Brooker

20:56

oh, okay, wild

Eric Stucky

so I used those books

and then when I had to actually learn

I used other books

but other than that

it's pretty much just hangining aroudn MSE

reading too many "which book should I use to study XXX" questions

Sami Brooker

ahhh sure okay

Eric Stucky

It looks like your book gets better around chapter 4

the author like actually knows

what he is talking about

chapter 3 I think was just a particularly bad one actually

Transcript for

♦ $Mathematics$ CRPxTumblr

Transcript for

♦ CRPxTumblr

♦ $Mathematics$ CRPxTumblr