Category Theory
Zulip Server
Archive

You're reading the public-facing archive of the Category Theory Zulip server.
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For all things related to this archive refer to the same person.

Stream: community: general

Topic: zulip for ct

Christian Williams (Mar 23 2020 at 17:00):

hello! look we can write category theory: $\Lambda \simeq \int^n \Lambda(n)\times \mathbb{F}(n,-)$

Jules Hedges (Mar 23 2020 at 17:01):

Hello everybody

Stelios Tsampas (Mar 23 2020 at 17:01):

Heyo :)

Jules Hedges (Mar 23 2020 at 17:04):

So do I understand, there's exactly 2 levels of hierarchy? "Streams" and then "topics"?

Christian Williams (Mar 23 2020 at 17:04):

yes.

Christian Williams (Mar 23 2020 at 17:04):

I think it ends up being just the right number of levels.

Jules Hedges (Mar 23 2020 at 17:05):

Are there guidelines somewhere for when something should be a stream and when a topic?

Christian Williams (Mar 23 2020 at 17:05):

you can customize a lot. I haven't mentally prepared a tutorial.

Christian Williams (Mar 23 2020 at 17:05):

well, I could just give the example from our team

Stelios Tsampas (Mar 23 2020 at 17:05):

I'd agree. Looks like we'll have to be precise w.r.t. what are why replying for, because there's this highlighting thing going on.

Christian Williams (Mar 23 2020 at 17:05):

actucr-zulip.png

Christian Williams (Mar 23 2020 at 17:06):

we had the streams grouped into: active projects, math subjects, organizational stuff, and random stuff

Christian Williams (Mar 23 2020 at 17:07):

but it's a more research-group oriented server; I imagine this one will be pretty different.

Christian Williams (Mar 23 2020 at 17:07):

you can make things private or public, control what people can see, make smaller groups for things

Christian Williams (Mar 23 2020 at 17:08):

Stelios Tsampas said:

I'd agree. Looks like we'll have to be precise w.r.t. what are why replying for, because there's this highlighting thing going on.

what do you mean? so this is using the "quote and reply" feature.

Christian Williams (Mar 23 2020 at 17:08):

it simulates threads without having to deal with big tree structures.

Jules Hedges (Mar 23 2020 at 17:08):

Ok. My first proposal would be a "meta" or "parliament" for public discussion of how the thing is run, like on stackexchange sites

Christian Williams (Mar 23 2020 at 17:09):

sure, sounds good.

Stelios Tsampas (Mar 23 2020 at 17:09):

Christian Williams said:

Stelios Tsampas said:

I'd agree. Looks like we'll have to be precise w.r.t. what are why replying for, because there's this highlighting thing going on.

what do you mean? so this is using the "quote and reply" feature.

Ah, I see! But I was saying that it's easy to get confused and reply to the wrong topic within a stream.

Christian Williams (Mar 23 2020 at 17:10):

oh, you get used to it.

Stelios Tsampas (Mar 23 2020 at 17:10):

Yeah, it's intuitive :)

Christian Williams (Mar 23 2020 at 17:10):

whenever you want to focus on just one topic, or on a stream, you just click on it.

Stelios Tsampas (Mar 23 2020 at 17:10):

Mhm!

Christian Williams (Mar 23 2020 at 17:10):

gives a nice mix of the "feed" of everything happening, versus the stuff in the topics you care about.

Jules Hedges (Mar 23 2020 at 17:17):

Any reason for me not to share the invite link now and let the hoards come?

Christian Williams (Mar 23 2020 at 17:17):

um, just depends if y'all think there are any other questions or things to figure out first

Jules Hedges (Mar 23 2020 at 17:18):

Not that I can think of...

Christian Williams (Mar 23 2020 at 17:18):

I think I'm fine with just opening it up and seeing what happens.

Jules Hedges (Mar 23 2020 at 17:19):

Ok!

Jules Hedges (Mar 23 2020 at 17:20):

Ah, maybe should maybe set some initial boundaries on the scope?

Jules Hedges (Mar 23 2020 at 17:21):

who is this for?

Jules Hedges (Mar 23 2020 at 17:21):

just researchers, or anyone who cares, or something in between?

Joe Moeller (Mar 23 2020 at 17:27):

The way I've described the hierarchy before is that Streams are like general themes, and topics are specific conversations.

jpt4 (Mar 23 2020 at 17:37):

Salutations and greetings, folks. Regarding the above remark on scope boundaries, I am merely an avocational student of category theory.

Christian Williams (Mar 23 2020 at 17:41):

hello!

Christian Williams (Mar 23 2020 at 17:41):

wow, a lot of people joining. it might be good if we introduced ourselves

Christian Williams (Mar 23 2020 at 17:41):

let me make an "introductions" topic

Christian Williams (Mar 23 2020 at 17:54):

we will make a topic in #general for stuff that we would want to "pin", like tutorials and code of conduct.

Christian Williams (Mar 23 2020 at 17:55):

also in this stream, new streams are announced, such as #meta .

Christian Williams (Mar 23 2020 at 17:55):

by default members are not subscribed to new streams, so you choose what to subscribe to.

Christian Williams (Mar 23 2020 at 19:40):

proposals for a server logo? some nice categorical little picture.

James Fairbanks (Mar 23 2020 at 19:42):

Christian Williams (Mar 23 2020 at 19:43):

classic.

James Fairbanks (Mar 23 2020 at 19:43):

since the box where the logo goes is a square

Stelios Tsampas (Mar 23 2020 at 19:43):

https://en.wikipedia.org/wiki/Limit_(category_theory)#/media/File:Functor_co-cone_(extended).svg

Stelios Tsampas (Mar 23 2020 at 19:44):

Throw in a little universal property, why not.

Jules Hedges (Mar 23 2020 at 19:44):

On the ACT Telegram we have a picture of Grothendieck with devil horns, maybe could steal that

Jules Hedges (Mar 23 2020 at 19:45):

If we're going to have a diagram as the logo I'm totally going to start a fight and say it should be an adjunction, not a square

Ben Steffan (Mar 23 2020 at 19:45):

https://en.wikipedia.org/wiki/Yoneda_lemma#/media/File:Yoneda_lemma_cd.svg

Perhaps a diagram for the proof of the Yoneda lemma?

Stelios Tsampas (Mar 23 2020 at 19:46):

Jules Hedges said:

If we're going to have a diagram as the logo I'm totally going to start a fight and say it should be an adjunction, not a square

Oh I'm all for that. The string diagram maybe? Otherwise it's a bit boring :/

Christian Williams (Mar 23 2020 at 19:49):

decisions, decisions... I mean everybody seems to love string diagrams. but maybe that's more an "applied" ct thing? I don't know.

Matt Cuffaro (he/him) (Mar 23 2020 at 19:50):

I like the adjunction idea, maybe something that signifies the reflective subcategory (CT reflecting Math or w/e)

Christian Williams (Mar 23 2020 at 19:50):

universal properties are probably the most indisputably CT thing.

Stelios Tsampas (Mar 23 2020 at 19:51):

I agree, it's the bread and butter.

James Fairbanks (Mar 23 2020 at 19:55):

I'd try to keep it simple so that beginners on the zulip could understand it. We don't want the logo to be something intimidating. We should send a signal that this community is welcoming. Not like "you must understanding Theorem T to join this zulip."

Christian Williams (Mar 23 2020 at 19:55):

I like adjunction because it's a unified duality like yin and yang.
for other dual concepts like limit and colimit, it's like they've been separated.

Christian Williams (Mar 23 2020 at 19:55):

true.

Christian Williams (Mar 23 2020 at 19:56):

people like @Bartosz Milewski have made lots of nice, non-intimidating visualizations of category theory.

Stelios Tsampas (Mar 23 2020 at 19:57):

Christian Williams said:

people like Bartosz Milewski have made lots of nice, non-intimidating visualizations of category theory.

Haha indeed, I love those cute little piggies :D.

John Baez (Mar 23 2020 at 19:57):

I think the logo should be the coherence law for the pentagonator in a tricategory, to keep out the riff-raff. :upside_down:

James Fairbanks (Mar 23 2020 at 19:59):

Stelios Tsampas (Mar 23 2020 at 19:59):

John Baez said:

I think the logo should be the coherence law for the pentagonator in a tricategory, to keep out the riff-raff. :upside_down:

Is this the one? https://upload.wikimedia.org/wikipedia/commons/thumb/7/74/Associahedron_K5_front.svg/500px-Associahedron_K5_front.svg.png

Christian Williams (Mar 23 2020 at 19:59):

adj-1.jpg

James Fairbanks (Mar 23 2020 at 19:59):

just scrolling through https://bartoszmilewski.com/

John Baez (Mar 23 2020 at 20:02):

Stelios Tsampas wrote:

Is this the one?

That's a simplified version, which works when certain squares commute. The general version is on pages 10-11 here.

Christian Williams (Mar 23 2020 at 20:05):

tricat1.png
tricat2.png
yes, this is just the thing.

Stelios Tsampas (Mar 23 2020 at 20:07):

What a beast!

James Fairbanks (Mar 23 2020 at 20:08):

yeah I think that will intimidate a few people

Christian Williams (Mar 23 2020 at 20:09):

yeah, we're kidding

James Fairbanks (Mar 23 2020 at 20:09):

oh ok, that wasn't clear

Christian Williams (Mar 23 2020 at 20:10):

oh sorry. our team definitely jokes a lot.

Stelios Tsampas (Mar 23 2020 at 20:10):

James Fairbanks said:

oh ok, that wasn't clear

Haha my bad!

Christian Williams (Mar 23 2020 at 20:16):

end-31.jpg

John Baez (Mar 23 2020 at 20:16):

The upside-down smiley was supposed to indicate that I was joking....

Christian Williams (Mar 23 2020 at 20:16):

Bartosz's cow became edgy when talking about ends and coends.

Emily Pillmore (Mar 23 2020 at 20:17):

Hola

Christian Williams (Mar 23 2020 at 20:17):

hello!

David Spivak (Mar 23 2020 at 20:17):

$\int^x C/x\times Fx$

Christian Williams (Mar 23 2020 at 20:17):

is that the Grothendieck construction of $F$?

Philip Zucker (Mar 23 2020 at 20:18):

I think if you just post the link https://categorytheory.zulipchat.com/ it says that you need an invite to join? Is there a way to turn that off?

David Spivak (Mar 23 2020 at 20:18):

yes

Christian Williams (Mar 23 2020 at 20:19):

Philip Zucker said:

I think if you just post the link https://categorytheory.zulipchat.com/ it says that you need an invite to join? Is there a way to turn that off?

no, I think that's intentional. we want to distribute using the invite link

Christian Williams (Mar 23 2020 at 20:20):

which you can generate in the settings dropdown: https://categorytheory.zulipchat.com/join/jyoh6wj29vvymhcd9nso7wfl/

Emily Pillmore (Mar 23 2020 at 20:21):

ahhh, they do have a desktop app! Fantastic. I can never follow these if they're web only

Christian Williams (Mar 23 2020 at 20:22):

oh yeah! should've mentioned that. yes, everyone the client makes it much better

Mike Stay (Mar 23 2020 at 20:47):

Stelios Tsampas said:

What a beast!

Hahaha, that was one of the easy ones! Check out the coherence law for the Breen polytope:
Screen-Shot-2020-03-23-at-2.46.09-PM.png
Screen-Shot-2020-03-23-at-2.46.15-PM.png
Or what I like to call the zag-ziggurat, aka the swallowtail equation:
Screen-Shot-2020-03-23-at-2.45.21-PM.png

Stelios Tsampas (Mar 23 2020 at 21:03):

Mike Stay said:

Stelios Tsampas said:

What a beast!

Hahaha, that was one of the easy ones! Check out the coherence law for the Breen polytope:

They're... surprisingly simple to parse actually ;).

John Baez (Mar 23 2020 at 23:20):

But I was saying that it's easy to get confused and reply to the wrong topic within a stream.

Yes. I always do this. Nobody else in the UCR group does it. I thought I was just dumb, but maybe they're using an interface that doesn't trick you this way.

Fabrizio Genovese (Mar 24 2020 at 12:53):

Jules Hedges said:

Ok. My first proposal would be a "meta" or "parliament" for public discussion of how the thing is run, like on stackexchange sites

I'd propose to copy-paste the Code of Conduct from the Telegram channel first. It's directly inspired by Haskell's IRC channel CoC and is working really well.

John Baez (Mar 24 2020 at 18:05):

That sounds good, Jules. Who is "in charge", if anyone? For example: there will eventually be some really obnoxious people here - sad, but it always happens. We are unable to block them individually, so we need a very fair "bouncer" for kicking people out. (In my own experience, fair procedures are good but wise individuals are utterly crucial.)

Jules Hedges (Mar 24 2020 at 18:06):

Currently Christian is the only admin, I hope we can run somewhat democratically using the #meta stream to discuss things publicly

Fabrizio Genovese (Mar 24 2020 at 18:08):

I have to say, for now we had very little problems with obnoxious people on the ACT telegram channel, way less than I expected :) There was just one guy, he got official warnings two times and then he left on his own. So it may be that we'll be lucky again!

John Baez (Mar 24 2020 at 18:15):

That's good. Yes, it's possible that category theory just cleanses people of all obnoxiousness.

But remembering what the category theory mailing list was like before certain people got too old to post, I sort of doubt it.

Fabrizio Genovese (Mar 24 2020 at 18:20):

Maybe we were just lucky because old people don't know Telegram is a thing? This being the case I bet we can be lucky again!

Matteo Capucci (he/him) (Mar 25 2020 at 09:12):

Shall we move the "Introduce yourself" topic under the "community" stream? It feels better suited IMO.

Fabrizio Genovese (Mar 25 2020 at 09:13):

Can topics be moved? :O

Matteo Capucci (he/him) (Mar 25 2020 at 09:14):

Only the gods know that, aka @Christian Williams

Nathanael Arkor (Mar 25 2020 at 13:27):

topics cannot be moved between streams in Zulip (https://github.com/zulip/zulip/issues/6427)

Nathanael Arkor (Mar 25 2020 at 13:27):

but we could always start a new one there

John Baez (Mar 25 2020 at 20:35):

No, topics cannot be moved. (I am a god.)