Spring 2022

Announcement

Hello everyone!


This term our seminar continues horsing around (this time in English). As was promised we shall cover higher categories and homotopical geometry. Note that although this is the second term of a two-term seminar, this term will be relatively independent of the first one.The syllabus looks something like this:

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§0 (Early February 2022) Monoidal model categories (based on chapter 4 in [Ho])


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§1 Homotopical categories


§1.1 (February–March 2022) Homotopy colimits revisited [Ri, Part I].


§1.1.1 Kan extensions.


§1.1.2 Derived functors.


§1.1.3 Enriched category theory.


§1.1.4 (Co-)Bar construction.


§1.1.5 Homotopy (co-)limits — new perspective.

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§1.2 (April 2022) Enriched homotopy theory [Ri, Part II].

§1.2.1 Weighted (co-)limits.


§1.2.2 Application to computations of homotopy (co-)limits.


§1.2.3 Weighted homotopy (co-)limits.


§1.2.4 Derived enrichment


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§1.3 (May 2022) Quasi-categories [Ri, Part IV], [Kerodon, Part I], [1, Part 3].


§1.3.1 Models for ∞-categories.


§1.3.2 Simplicial categories and homotopy coherence.


§1.3.3 Isomorphisms in quasi-categories.


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§2 Topos theory


§2.1 (February 2022) Categorical preliminaries [MM, Chapter I].

§2.1.1 Subobject classifiers.


§2.1.2 Subfunctors and Sieves.


§2.2.2 Heyting algebras.


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§2.2 (February 2022) Sheaves in the classical sense. Review [MM, Chapter II].


§2.3 (March–April 2022) Grothendieck topologies on model categories [MM, Chapter III], [TV], [Jo]

§2.3.1 Grothendieck topologies on a category. (Model) Sites.

§2.3.2 Sheaves of sets on a site.

§2.3.3 Prestacks on model sites

§2.3.4 Local model structure. Stacks on model sites.


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§2.4 (April–May 2022) Topoi [MM, Chapter IV], [TV], [Jo].


§2.4.1 Classical (lower) topoi.


§2.4.2 Geometric morphisms of topoi.


§2.4.3 Model topoi.


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References:


[Ci] Cisinski, Denis-Charles. Higher categories and homotopical algebra. Vol. 180.


Cambridge University Press, 2019.


[Ho] Hovey, Mark. Model categories. No. 63. American Mathematical Soc., 2007.


[MM] MacLane, Saunders, and Ieke Moerdijk. Sheaves in geometry and logic: A first


introduction to topos theory. Springer Science & Business Media, 2012.


[Ri] Riehl, Emily. Categorical homotopy theory. Vol. 24. Cambridge University Press,


2014.


[TV] Toën, Bertrand, and Gabriele Vezzosi. Homotopical algebraic geometry I: Topos


theory. Advances in mathematics 193.2 (2005): 257-372.


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Scientific advisor of the seminar prof. Dmitry Kaledin


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If you want to give a talk e-mail


Grisha Taroyan at tgv628@yahoo.com


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February 7th, speaker: Grisha Taroyan, topic: an overview of the program. Notes. Video.

We discussed plans for this term and two examples of homotopical geometry: derived manifolds and Grothendieck topologies on model categories. 

February 9th, speaker: Grisha Taroyan, topic: Grothendieck dream. Notes. Video.

February 14th, speaker: Grisha Taroyan, topic: Postnikov towers and group cohomology . Notes. Video.

February 16th, speaker: Grisha Taroyan, topic: Posets, enrichment, and fibrations. Notes. Video.



February 16th, speaker: Grisha Taroyan, topic: Posets, enrichment, and fibrations. Notes. Video.

February 23d, speaker: Grisha Taroyan, topic: characteristic functions and subobject classifiers Notes. Video.

February 28th, speaker: Arseny Kryazhev, topic: Kan extensions. Notes. Video.

March 18th, speaker: Grisha Taroyan, topic: Monoidal categories. Notes. Video.

March 21st, speaker: Grisha Taroyan, topic: categorical preliminaries of topos theory-2. Notes. Video.

March 25th, speaker: Grisha Taroyan, topic: Monoidal model categories - 2. Notes. Video.

March 28th, speaker: Grisha Taroyan, topic: categorical preliminaries of topos theory-3. Notes. Video.

April 1st, speaker: Grisha Taroyan, topic: Monoidal model categories - 3. Notes. Video.

April 4th, speaker: Misha Kornev, topic: Kan extensions. Additional topics. Notes. Video.

April 8th, speaker: Misha Kornev, topic: Sheaves of Sets - 1. Notes. Video.

April 11th, speaker: Misha Kornev, topic: Sheaves of Sets - 2. Notes. Video.

April 15th, speaker: Misha Kornev, topic: Sheaves of Sets - 3. Notes. Video.

April 18th, speaker: Misha Kornev, topic: Sheaves of Sets - 4. Notes. Video.

April 22d, speaker: Cyrill Barlasov, topic: Quasicategories - 1. Notes. Video.

April 25th, speaker: Cyrill Barlasov, topic: Quasicategories - 2. Notes. Video.

April 29th, speaker: Grisha Taroyan, topic: Grothendieck topologies - 1. Notes. Video.

May 2nd, speaker:  Cyrill Barlasov, topic: Quasicategories - 3. Notes. Video.

May 6th, speaker:  Cyrill Barlasov, topic: Quasicategories - 4. Notes. Video.

May 9th, speaker:  Grisha Taroyan, topic: Zariski site, Sheaves on sites. Notes. Video.

May 13th, speaker:  Cyrill Barlasov, topic: Quasicategories - 5. Notes. Video.

May 16th, speaker:  Grisha Taroyan, topic: Associated sheaf functor on arbitrary sites. Notes. Video.

May 20s, speaker:  Grisha Taroyan, topic: Elementary properties of categories of sheaves on sites. Notes. Video.

May 23d, speaker: Cyrill Barlasov, topic: Quasicategories - 6. Notes. Video.

May 27th, speaker:  Egor Teplyakov, topic: S-categories and simplicial localization. Notes. Video.

May 30s, speaker:  Grisha Taroyan, topic: Conclusion. Notes. Video.