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visite Ulrik BUCHHOLTZ & mini-course HoTT
by Groupe de travail catégories 17 Mar '26

17 Mar '26

Bonjour, Notre invité *Ulrik Buchholtz* arrivera lundi prochain (23 mars) et restera jusqu'au 26 avril avec une interruption d'une semaine (du 12 au 18 avril). En tant qu'invité de l'EUR <https://eur.univ-paris13.fr/> il donnera un mini-cours d'environ trois séances sur la *théorie homotopique de types* (HoTT) destiné aux étudiants de master, mais aussi aux doctorants, postdocs et permanents. Si ça vous intéresse vous et invités à remplir ce sondage <https://lettucemeet.com/l/KwWpn> pour indiquer vos disponibilités. Dear all, Our guest *Ulrik Buchholtz* will be arriving next Monday (*March 23*) and will be staying until *April 26*, with a one-week break from April 12 to 18. As a guest of the EUR <https://eur.univ-paris13.fr/>, he will give a mini-course of about three sessions on *Homotopy Type Theory (HoTT)*. This course is *aimed at* Master’s students, but PhD students, postdocs, and permanent staff are also welcome to attend. If you are interested, you are invited to fill out this poll <https://lettucemeet.com/l/KwWpn> to indicate your availability. Best, Jonas

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Pas de GdT aujourd'hui
by Groupe de travail catégories 13 Mar '26

13 Mar '26

Hi! To save potential needless travel, there will be no GdT today. Starting months ago, a colleague had planned a workshop today under the assumption that rooms in the new building would be functional (which they are not), so I accepted to give up our room booking. Best wishes, Morgan

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BBB en panne
by Groupe de travail catégories 20 Feb '26

20 Feb '26

Je suis désolé, il semble que le service BBB est en panne actuellement, donc nous ne pourrons diffuser ni enregistrer l'exposé de Jad... À bientôt, Morgan

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GdT demain
by Groupe de travail catégories 13 Feb '26

13 Feb '26

Bonjour! Demain, à 10h30 en B107, Jad Koleilat nous parlera sur le sujet suivant. --- Cartesian Differential Categories are a categorical axiomatisation of differentiation between vector spaces. A CDC is a cartesian category equipped with a differential operator, associating to each morphism f : A -> B a morphism Df : A x A -> B. The category of real finite dimentional vector spaces and smooth function is an example of CDC. Historically, they were discovered wile studying categorical models of a certain logic called Differential Linear Logic (DiLL). Since 2021, we know that there exists a strong duality between CDC and models of DiLL : the coKleisli of every model of DiLL is a CDC and every CDC embeds fully and faithfully into the coKleisli of a model of DiLL. This duality can appear somewhat surprising as it is not often that such logical/mathematical duality exists especially in the context of non-discrete structures. In this talk, I will explain what are CDC, what are models of DiLL, the duality between them and try to convey the intuitions I have on those structures. --- Il est possible que la réunion soit plus court que d'habitude. Bien cordialement, Morgan Rogers

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no meeting tomorrow
by Groupe de travail catégories 05 Feb '26

05 Feb '26

Dear all, there's no meeting tomorrow, we don't have a speaker. Sorry for the late notice and see you next week! Best, Jonas

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GdT demain
by Groupe de travail catégories 30 Jan '26

30 Jan '26

Hi! Tomorrow at 10:30 in B107 (we should have a key this time, even if it isn't the one that was lost...) Quentin will be continuing the reading group on Synthetic Differential Geometry. Last time he had told us about C-oo-rings, and this time he will be explaining how to build a site out of these which will house a model of SDG. I won't be there unfortunately, but Jonas still knows the login details so he should be able to get the BBB working: https://bbb.lipn.univ-paris13.fr/b/rog-vao-uwm-s2j Next week we may have Christian telling us something about K-theory if he is available (let me know @Christian) Best, Morgan

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tomorrow : Jonas on sheaves on cartesian spaces as a classifying topos
by Groupe de travail catégories 22 Jan '26

22 Jan '26

Dear all, tomorrow January 23, I will give a talk about "Sh(Cart) spaces as a classifying topos", following my notes [1,2]. Room B107 at 10h30 as usual. Best, Jonas PS: here's the BBB link in case anybody wants to watch remotely, but please let us know if you want to do so, so we can set it up: https://bbb.lipn.univ-paris13.fr/b/rog-vao-uwm-s2j [1] https://github.com/jonas-frey/pdfs/blob/master/cartesian-may-2023.pdf [2] https://github.com/jonas-frey/pdfs/blob/master/real-continuous.pdf

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Re: [GdT Categories] tomorrow : Quentin on C-infty rings
by Groupe de travail catégories 16 Jan '26

16 Jan '26

Finalement je l'ai retrouvé, je suis connecté. Le 16/01/2026 à 10:30, A. DJAMENT a écrit : > Cher(e)s collègues, > > > l'heure approche mais je n'ai pas le lien de connexion... Quelqu'un > pourrait-il le renvoyer ? > > Merci d'avance, > > Aurélien. > > Le 16/01/2026 à 07:57, Groupe de travail catégories a écrit : >> Bonjour tout le monde, et bonne année 2026 ! >> >> >> Je participerai en visio à la séance de ce matin. >> >> >> À bientôt, >> >> Aurélien. >> >> Le 15/01/2026 à 20:27, Groupe de travail catégories a écrit : >>> Reminder: We'll meet tomorrow (Friday 16 January) at 10:30 in B107, >>> and Quentin will tell us about C-infinity rings. >>> >>> Please let us know if you want to join remotely, so that we can set >>> up the BBB. >>> >>> Best, >>> >>> Jonas >>> >>> On 1/11/26 13:53, Groupe de travail catégories wrote: >>>> Hi! >>>> >>>> The poll results are in. We will meet on Friday morning in B107 at >>>> 10:30 from now on, at least until we move into the new building. I >>>> have booked the room accordingly. >>>> >>>> This Friday we will likely have a recap of what has been covered in >>>> the reading group so far plus a little extra. I'll send out a >>>> reminder and the BBB link later in the week. >>>> >>>> Bon dimanche, >>>> Morgan >>>> _______________________________________________ >>>> Categories mailing list >>>> Categories(a)lipn.univ-paris13.fr >>>> https://lipn.univ-paris13.fr/listes-lipn/listinfo/categories >>> _______________________________________________ >>> Categories mailing list >>> Categories(a)lipn.univ-paris13.fr >>> https://lipn.univ-paris13.fr/listes-lipn/listinfo/categories >> _______________________________________________ >> Categories mailing list >> Categories(a)lipn.univ-paris13.fr >> https://lipn.univ-paris13.fr/listes-lipn/listinfo/categories

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Nouveau créneau GdT
by Groupe de travail catégories 16 Jan '26

16 Jan '26

Hi! The poll results are in. We will meet on Friday morning in B107 at 10:30 from now on, at least until we move into the new building. I have booked the room accordingly. This Friday we will likely have a recap of what has been covered in the reading group so far plus a little extra. I'll send out a reminder and the BBB link later in the week. Bon dimanche, Morgan

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Sondage nouveau semestre
by Groupe de travail catégories 08 Jan '26

08 Jan '26

Happy New Year! Since some people's timetables will have changed from last semester, here is a new poll for the meeting time: https://www.when2meet.com/?34151870-DkBAn Please fill it in even if you would only be able to attend remotely. We will probably keep the chosen slot until the end of the academic year in July and choose again in September. We won't have a session tomorrow, but I hope to announce the new slot by the end of the week for next week. Please do let me know if you will have time to prepare something to present in the working group! Our next session will otherwise likely be a continuation of the reading group started in December. Best wishes, Morgan

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