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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, ...

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
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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 $C_m(\tilde X)$ …
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  • 1,990
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 …
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0 votes
1 answer
188 views

cohomology algebra of unordered configuration space on Euclidean space

In Homology of $C_{n+1}$-spaces, $n\geq 0$, F.R. Cohen, Lecture Notes in Mathematics, Vol. 533, page 210 (the preface part before contents): Line 2: ... is used to compute the precise algebra struct …
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2 votes
1 answer
336 views

fiber sequence of principal bundles

Let $G$ be a group, either a Lie group or a discrete group. Let a principal $G$-bundle $$ G\to E\to B,$$ then $B=E/G$, the orbit space under action of $G$. Let $BG$ be the classifying space of $G$. …
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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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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^{ …
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  • 1,990
9 votes
1 answer
540 views

cohomology of classifying space of permutation groups

Let $\rho^*: H^*(G_k(\mathbb{R}^\infty))\to H^*(B\Sigma_k)$ be the induced homomorphism of cohomology with coefficients in $\mathbb{Z}_2$. What is the image $\text{Im} \rho^*$? …
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4 votes
1 answer
600 views

Relation between cohomology of ordered and unordered configuration spaces

Suppose the cohomology algebra $H^*(F(M,p);\mathbb{Z}/p\mathbb{Z})$ is known. … $, the question is answered at Relation between cohomology of ordered and unordered configuration spaces? …
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4 votes
1 answer
419 views

homology of configuration spaces of non-compact manifolds

Let $M$ be a manifold. Let $F(M,n)$ be the configuration space of $n$-tuples on $M$. Let $B(M,n)=F(M,n)/S_n$, where $S_n$ is the symmetric group of order $n$, be the corresponding unordered config …
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4 votes
1 answer
741 views

cohomology ring of symmetric group of order $3$

What is the cohomology ring $$ H^*(S_3;\mathbb{Z})?$$ My attempt: I want to use mathematical induction on $n$ for $S_n$. For $n=1$, $S_1$ is trivial. …
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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
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. …
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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. …
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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? …
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