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for questions about deformation theory, including deformations of manifolds, schemes, Galois representations, and von Neumann algebras.

2 votes

Is the algebra of sections of a bundle of complex Clifford algebra over an oriented Riemanni...

Let's try this: assume that the complex vector bundle you start with has even fiber dimension such that the corresponding Clifford algebra bundle is a bundle of complex matrix algebras. Suppose furthe …
Stefan Waldmann's user avatar
18 votes

Clifford algebras as deformations of exterior algebras

In addition to the answer of Bertram Arnold, let me point out that there is a very explicit formula for "fermionic" Weyl-Moyal product. Let us assume that your vector space $V$ (or module) is defined …
Stefan Waldmann's user avatar
1 vote

How to compute the deformation quantizations of a polynomial Poisson algebra?

Not a complete answer but some observations. First it might be necessary not to take formal power series but formal Laurent series in order to get a reasonable behaviour of the Hochschild cohomology. …
Stefan Waldmann's user avatar
8 votes
Accepted

Some elementary questions about deformation quantization

a lot of questions, let me try on some of them :) The bad news is that in most of the interesting situations the higher order terms of the star product, the $B_i$ will not vanish. Heuristically this …
Community's user avatar
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3 votes

Open problems in deformation theory

Deformation theory is of course a very very wide field and one can take many different points of view on it. Working in deformation quantization, i.e. formal associative deformations of algebras and t …
Stefan Waldmann's user avatar
14 votes

Deformation Quantization

Unfortunately, there is no real textbook on DQ around. One has Fedosov's book on his construction of star products including a detailed exposition of his index theorem. There is a chapter on DQ in t …
Stefan Waldmann's user avatar
3 votes

graded generalization of the Moyal–Weyl product

Yes, it's just putting signs correctly. Martin Bordemann has a preprint from the 90s where he adapted Fedosov's construction in the graded setting. If you are only interested in the flat situation thi …
Stefan Waldmann's user avatar
3 votes

Equivalence of star products on two differents Poisson algebras?

to 1) A $\mathbb{k}[[\hbar]]$-linear map between $A[[\hbar]]$ and $B[[\hbar]]$ is necessarily of the form $T = T_0 + \hbar T_1 + \cdots$ with $T_r\colon A \longrightarrow B$ being $\mathbb{k}$-linear …
Stefan Waldmann's user avatar
6 votes
Accepted

Formal series convergence in deformation quantization and $C^*$-condition

OK, let me give a try on this question. There are several problems hidden underneath which one has to address. First, for physical reasons a formal deformation is not sufficient. $\hbar$ is a constan …
Stefan Waldmann's user avatar
8 votes
Accepted

In the dictionary between Poisson and Quantum, what corresponds to Coisotropic?

Concerning your first question I have a couple of suggestions: first coisotropic is in some sense the best we can have in a truely Poisson situation: there is nothing like lagrangian (unfortunately). …
Stefan Waldmann's user avatar
2 votes

Tamarkin-Tsygan Formalism

Well, this is probably not the deep insight you are looking for, but if you consider the polyvector fields on a manifold, you can first define the Lie derivative $L_X$ of a polyvector field $X$ on dif …
Stefan Waldmann's user avatar
5 votes
3 answers
2k views

Differential Hochschild Cohomology, general tools?

Background: in deformation quantization one wants to construct formal associative deformations (the star products $\star$) of the algebra of smooth complex-valued functions on a Poisson manifold $M$ i …
3 votes

Reverse Engineering to find deformation problem (from cohomology groups)?

In this generality, I would say that this is not possible: the same cohomology can be responsible for controlling quite different deformations problems. Just an example: in formal deformation quantiz …
Stefan Waldmann's user avatar