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21 votes
3 answers
2k views

Formality of classifying spaces

Let $G$ be a compact Lie group (or reductive algebraic group over $\mathbb{C}$), and let $BG$ be its classifying space. Fix a prime $p$. Let $\mathcal{A}$ denote the dg algebra of singular cochains on ...
Geordie Williamson's user avatar
18 votes
1 answer
991 views

Higher homotopy algebraic structure on the homology of an operad

Given a DGA $A$, then by standard techniques such as homological perturbation theory, the ring structure on the homology $H(A)$ extends to a minimal $A_\infty$-algebra structure such that $H(A)$ is ...
Jeffrey Giansiracusa's user avatar
13 votes
5 answers
2k views

$A_\infty$-categories basic reference

Can anyone provide me with a basic reference on $A_\infty$ categories?
user avatar
12 votes
2 answers
799 views

Reference for functors in Kadeishvili's C_\infty paper

In his paper Cohomology $C_\infty$-algebra and rational homotopy type, Tornike Kadeishvili describes how the rational cohomology of a simply-connected space carries the structure of a $C_\infty$-...
Mark Grant's user avatar
  • 35.9k
7 votes
3 answers
3k views

Hochschild cohomology and A-infinity deformations

When we are dealing with ordinary things or dg things (where thing = algebra or category), I think I understand how HH^2 corresponds to 1st order deformations and HH^3 corresponds to obstructions. ...
Kevin H. Lin's user avatar
7 votes
0 answers
244 views

Operad-free proofs of rectification of homotopy ($A_\infty/L_\infty$) algebras?

If (say) $L$ is an $L_\infty$-algebra, then it is known that under certain conditions there exists a quasi-isomorphic $L_\infty$-algebra $L'$ which is a differential graded Lie algebra: all ternary ...
AlexArvanitakis's user avatar
5 votes
1 answer
367 views

Homotopy invariant structure: Stasheff versus Segal

To describe homotopy invariant algebraic structures on spaces, there are different approaches. The Stasheff / Boardman–Vogt / May approach, where operations and equations are replaced by spaces of ...
Martin Frankland's user avatar
5 votes
1 answer
675 views

Resolution of a module as an $A_\infty$ module over resolution of an algebra

The following question looks like a basic question on resolutions over commutative rings, unfortunately I was not able to find a reference. Let $A$ be a regular commutative noetherian ring (and ...
Sasha Pavlov's user avatar
  • 1,545
5 votes
0 answers
303 views

Recovering an A-infinity structure on an Ext-algebra from a quiver presentation

Let $A=KQ/I$ be a basic finite dimensional algebra given by a quiver with relations. Let $S$ denote the direct sum of the corresponding simple modules. According to [Keller: A-infinity algebras in ...
Julian Kuelshammer's user avatar
5 votes
0 answers
151 views

$A_\infty$ structure on sum of twists of structure sheaf

Fix $n$ and let $P^n$ be projective $n$-space. Let $S = k[x_0, \dots, x_n]$. Set $A^0 = \bigoplus_{d \ge 0} H^0(P^n, \mathcal{O}(d))$ and $A^n = \bigoplus_{d < -n} H^n(P^n, \mathcal{O}(d))$. I ...
Steven Sam's user avatar
  • 10.7k
4 votes
1 answer
244 views

Are these two natural $A_\infty$-structures on the realization of a cosimplicial commutative algebra isomorphic?

Given a cosimplicial commutative algebra $A^\bullet$ over a field of characteristic zero, there are two ways of producing an $A_\infty$-structure on its realization $|A^\bullet| := \int^\Delta C^*(\...
Bertram Arnold's user avatar
4 votes
0 answers
126 views

Minimal model for $A_\infty$-categories

Is there a reference for existence and construction of the minimal model of an $A_\infty$-category? Most references I found ultimately refer to Lefèvre-Hasegawa's thesis but there doesn't seem to be a ...
Eugenio Landi's user avatar
4 votes
0 answers
225 views

Natural transformations of $A_\infty$-functors (between dg-categories) are "directed homotopies" (reference?)

Let $\mathbf A$ and $\mathbf B$ be dg-categories over a field, viewed as $A_\infty$-categories. The $A_\infty$-category (actually, dg-category) of strictly unital $A_\infty$-functors $\mathbf A \to \...
Francesco Genovese's user avatar
3 votes
1 answer
167 views

Theory of $n$-truncated $A_\infty$ categories/functors?

One can define certain higher categorical truncations. For example, a discussion from the quasi-categories point of view can be found in HTT 5.5.6. On the other hand, as a model of linear $\infty$-...
Bingyu Zhang's user avatar
3 votes
0 answers
261 views

On the Hochschild cohomology of the minimal model of an $A_\infty$ algebra

Suppose $(A, (\mu_k))$ is a (curved) $A_\infty$ algebra, and let $(\tilde A, (\tilde\mu_k))$ be its minimal model. Now, we have two Hochschild cohomology rings $HH^*(A)$ and $HH^*(\tilde A)$. (It may ...
Hang's user avatar
  • 2,789
1 vote
0 answers
79 views

Reference request for showing open(resp. closed) string field theory has A-infinity(resp. L-infinity) algebra structure

I've now begun to study about the relationship between open(resp. closed) string field theory and A-infinity(resp. L-infinity) algebra structure. For the A-infinity case, I'd already heard that the ...
ChoMedit's user avatar
  • 285