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A branch of algebraic topology concerning the study of cocycles and coboundaries. It is in some sense a dual theory to homology theory. This tag can be further specialized by using it in conjunction with the tags group-cohomology, etale-cohomology, sheaf-cohomology, galois-cohomology, lie-algebra-cohomology, motivic-cohomology, equivariant-cohomology, ...

5 votes
1 answer
404 views

triviality of homology with local coefficients

Let $X$ be a manifold or a CW-complex. Let $\pi: \tilde X\longrightarrow X$ be a covering map. Let $\pi_1(X)$ be the fundamental group of $X$ and let $\rho: \pi_1(X)\longrightarrow O(n)$ be an ort …
Shiquan Ren's user avatar
  • 1,990
2 votes
1 answer
270 views

can the actions of fundamental groups annihilate homology?

Let $X$ be a path-connected manifold (or a CW complex). Let $\pi_1(X)$ be the fundamental group of $X$. Let $\pi: \tilde X\longrightarrow X$ be a covering map. For each $m\geq 0$, let $C_m(\tilde X)$ …
Shiquan Ren's user avatar
  • 1,990
7 votes
0 answers
419 views

kernel of the mod $2$ Bockstein on the first cohomology group

Let $M$ be a path-connected finite $CW$-complex. Suppose the first integral homology group is $H_1(M;\mathbb{Z})= \mathbb{Z}_2^{\oplus r}\oplus A$ where $r\geq 1$ and $A$ is a finite abelian group of …
Shiquan Ren's user avatar
  • 1,990
1 vote
0 answers
125 views

cohomology ring of compact submanifolds of Euclidean spaces

Suppose we have a compact $m$-dimensional submanifold $M$ of $\mathbb{R}^N$ and we want to know the cohomology ring $H^*(M;\mathbb{Z})$. … Question: are there any software / programming that can give the cohomology ring $H^*(M)$ automatically for any compact submanifold of Euclidean spaces, given by finitely many equations of coordinates? …
Shiquan Ren's user avatar
  • 1,990
1 vote
1 answer
297 views

torsion part of the cohomology module of configuration spaces of manifolds

I want to find the mod $p$ torsion part of the cohomology module $$ H^*(C_p(M);\mathbb{Z}) $$ for any prime $p$. … If I cannot find a statement for general $M$, then I want to find as many as possible examples of $M$ such that the mod $p$ torsion part of the cohomology module $ H^*(C_p(M);\mathbb{Z}) $ are known …
Shiquan Ren's user avatar
  • 1,990
2 votes
1 answer
619 views

Schubert calculus and Pieri's formula

In the lecture notes Grassmannians: the first example of a moduli space. MIT Open Course Ware. page 7: Are there any formal publications (books/papers) where I can find the formula?
Shiquan Ren's user avatar
  • 1,990
-2 votes
1 answer
290 views

stable splitting into a wedge sum [closed]

Suppose $X$ is a CW-complex such that there is a stable splitting of $X$ into wedge sum $$ \Sigma^t X\cong \bigvee _{k=1}^\infty Y_k. $$ (1). Does this imply $$ X\to \Sigma^tX\to \bigvee _{k=1}^\inf …
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  • 1,990
1 vote
1 answer
292 views

Unordered configuration space of $\mathbb{R}P^1$

In the paper GEOMETRY OF TRUNCATED SYMMETRIC PRODUCTS AND REAL ROOTS OF REAL POLYNOMIALS, JACOB MOSTOVOY, Bull. London Math. Soc. (1998) 30 (2): 159-165, Theorem 2. (b): $TP^n(\mathbb{R}P^1)$ is ho …
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  • 1,990
3 votes
1 answer
364 views

cohomology ring of configuration spaces

In the paper configuration spaces: applications to Gelfand-Fuks cohomology, by F. Cohen and L. Taylor, Bull. Amer. Math. Soc., 1978, theorem 1, I did not find the proof. … How to obtain the cohomology ring $H^*(F(M,k);\mathbb{F})$, where $F(M,k)$ is the ordered configuration space, $\mathbb{F}$ is a field? Where could I find the proof? …
Shiquan Ren's user avatar
  • 1,990
3 votes
1 answer
1k views

cohomology of the orbit space of a group action

Suppose the induced action of $G$ on the cohomology algebra $H^*(M,F)$ is known. We want to obtain $H^*(M/G;F)$. Is there any method or procedure to follow? …
Shiquan Ren's user avatar
  • 1,990
2 votes
1 answer
129 views

cohomology algebra of submanifold in euclidean space

1,\\ \text{ for }i\neq j, x_{3i+1}\neq x_{3j+1} \text{ or } x_{3i+2}\neq x_{3j+2} \text{ or }x_{3i+3}\neq x_{3j+3} \}, \end{multline} is there any computer software or programming that can give the cohomology … Can the computer give a very complicated simplicial complexes to approximate the manifold and compute the cohomology algebra? …
Shiquan Ren's user avatar
  • 1,990
1 vote
1 answer
257 views

permutation action on cohomology of Stiefel manifolds

In the paper The cohomology rings of real Stiefel manifolds with integer coefficients, Martin Čadek, Mamoru Mimura, and Jiří Vanžura, J. Math. Kyoto Univ. … Volume 43, Number 2 (2003), 411-428., the cohomology rings $$ H^*(V_k(\mathbb{R}^n);\mathbb{Z}_2), $$ $$ H^*(V_k(\mathbb{R}^n);\mathbb{Z}), $$ are obtained. …
Shiquan Ren's user avatar
  • 1,990
1 vote
1 answer
373 views

configuration spaces of real projective space

In http://arxiv.org/abs/1502.04258, the cohomology ring $$ H^*(F(\mathbb{R}P^n,k);R)$$ is obtained for any commutative ring $R$ with unit and $2$ invertible. …
Shiquan Ren's user avatar
  • 1,990
2 votes
1 answer
385 views

cohomology of orthogonal (or general linear) group over finite fields

Let $\mathbb{Z}_2=\mathbb{Z}/2\mathbb{Z}$. Let $$ O(\mathbb{Z}_2^{\oplus k})=\{A\mid A \text{ is a } k\times k \text{ - matrix with entries } 0,1, det(A)=\pm 1\} $$ What is $$ H^*(BO(\mathbb{Z}_2^{ …
Shiquan Ren's user avatar
  • 1,990
1 vote
1 answer
612 views

cohomology of orthogonal group of integers

Let $$ O(\mathbb{Z}^{\oplus k})=GL(\mathbb{Z}^{\oplus k})\cap O(k). $$ What is $$ H^*(BO(\mathbb{Z}^{\oplus k});\mathbb{Z})? $$ If it cannot be computed out, can we get $$ H^*(O(\mathbb{Z}^{\oplus …
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  • 1,990

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