## Applied Category Theory | 240 Members | |

3 Servers |

Timestamp | Message | |
---|---|---|

5 Dec 2019 | ||

18:20:05 | Tobias Heindel (Telegram) | In reply to Jules HedgesThanks for helping the good cause :) |

18:25:49 | GNU/Brett G. | In reply to Jules HedgesTruth |

20:26:24 | Francisco | In reply to Tobias HeindelHa, nice! 😄 |

6 Dec 2019 | ||

07:02:07 | Abdul set a profile picture. | |

12:03:40 | Andrea Censi | In reply to davidadOn the left hand side we have both `X->Y` and `Sequences[X]` . X here appears both contravariant and covariant. |

16:27:59 | davidad | In reply to Andrea CensiThe transform is from the functor Hom(X,Y) to the functor Hom(Sequence(X),Sequence(Y)): X is contravariant in both occurrences (and Y is covariant) |

22:48:38 | 앜 joined the room. | |

7 Dec 2019 | ||

11:47:05 | Jules Hedges | Pre-announcement for the 2020 ACT Adjoint School: https://www.appliedcategorytheory.org/adjoint-school-act-2020/ |

11:47:20 | Jules Hedges | Applications will open soon, and will probably be due before the end of the year |

11:47:42 | Jules Hedges | The tutors are Valeria de Paiva, Mike Shulman, Mike Johnson and a 4th to be confirmed |

11:47:54 | Jules Hedges | The in-person part of the school will be at MIT in July |

12:29:28 | Daniele | Nice |

12:30:11 | Waifod | In reply to Jules HedgesDamn, that might be a problem. |

12:31:50 | Jules Hedges | Why, because of politics? |

12:32:30 | Waifod | No, I will be defending my thesis in July. |

12:34:37 | Jules Hedges | Ah |

12:36:35 | Jules Hedges | There's not really anywhere good in the world to hold an international event, but the USA is still one of the worst in terms of who is able to travel there |

14:28:52 | Tx Rx | Yesss |

14:29:37 | Tx Rx | My friend has submitted his papers for visa 2 years ago and is still waiting |

8 Dec 2019 | ||

07:06:34 | Tobias Heindel (Telegram) | In reply to Jules HedgesBarbados is great ! |

19:55:26 | ☕️ Lamp changed their profile picture. | |

9 Dec 2019 | ||

14:45:22 | Eigil Rischel joined the room. | |

16:57:30 | GNU/Brett G. changed their profile picture. | |

10 Dec 2019 | ||

00:05:47 | Eduardo Ochs | Hey, anyone here knows a good formal proof that the "obvious" way of constructing explicitly the subobject classifier of a topos of the form Set^D, where D is a finite poset, works? |

08:03:49 | GNU/Brett G. changed their profile picture. | |

11 Dec 2019 | ||

18:58:14 | Andrea Censi | I found many answers regarding my question about the relation between parametric polimorphism and natural transformations in the paper "Theorems for Free" by Wadler. https://ecee.colorado.edu/ecen5533/fall11/reading/free.pdf |

12 Dec 2019 | ||

14:51:41 | Philip Zucker | For people in the boston area are interested, I'm giving a small informal talk on relation algebra at the Categorical Databases meetup tonight. https://www.meetup.com/Categorical-Databases/events/266967988/ |

15:09:36 | Ape Man | I have a reference question about categories enriched in presheaf categories. Let A be some monoidal cat. Then PSh(A) has a monoidal structure given by Day convolution. I'm using PSh(A)-enriched categories for a project and I wonder what other applications these have. So I would be extremely grateful if someone can point out to a paper where these categories have been studied either in general or for some concrete choice of A. One way in which such categories arise is by a generalized Kleisli category construction: suppose I have an action F : A^op -> End(C) of the monoidal category A^op on C (by action I mean a lax monoidal functor, some people call this and actegory), then I get a PSh(A)-enrichment of C since a |-> hom(x, F(a,y)) gives me a presheaf (one has to check some compatibilities) |

15:10:53 | Ape Man | I am also very interested in a reference for this Kleisli category construction, it's very natural so I would be very surprised if it hasn't been considered before |

16:49:59 | Dhruva changed their profile picture. |

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