These are notes written for myself to better understand some papers/books and make comments to them. Use at your own risk.

1) Comments to Beilinson, Drinfeld, Chiral algebras, Colloquium Publications, vol. 51, 2004 (last modified 12 dec 2017)

We develop to some extent the theory of chiral algebras for perverse sheaves. For example, we explain the existence of free chiral algebras and enveloping chiral algebras of Lie-* algebras in the setting of perverse sheaves.

2) Comments to Rozenblyum, Gaitsgory, A Study in Derived Algebraic Geometry: Volumes I and II, Mathematical Surveys and Monographs

Volume: 221; 2017 (last modified 8 dec 2018)

We try to justify their dictionary and prove some claims left for a reader. There are also some comments to Lurie inside.

3) Comments to Braverman, Gaitsgory, Deformations of Local Systems and Eisenstein Series, GAFA 2008, Vol. 17, Issue 6, 1788–1850 (last modified 18 dec 2017)

Many things are left for a reader to be worked out himself. We try to do this.

4) Comments to Feigin, Finkelberg, Kuznetsov, Mirković, Ivan Semi-infinite flags. II. Local and global intersection cohomology of quasimaps' spaces. Differential topology, infinite-dimensional Lie algebras, and applications, 113–148, Amer. Math. Soc. Transl. Ser. 2, 194, Adv. Math. Sci., 44, Amer. Math. Soc., Providence, RI, 1999 (last modified 23 dec 2017)

We give a new proof of a result of this paper, which allows to avoid the theory of weights. This simplifies the definition of the action of the dual Lie algebra on the Eisenstein series corresponding to the trivial local system.

5) Comments to Krahmer, Notes on Koszul algebras (last modified 29 Sept 2017)