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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, ...
3
votes
2
answers
318
views
cohomology algebra of braid spaces, configuration spaces
Cohen, Lecture Notes in Mathematics, Vol. 533, Chapter 5, 6, 7, 8, 9, 10, 11, the cohomology algebra $H^*(B(\mathbb{R}^{n+1},p),\mathbb{Z}_p)$, for $p$ prime and $B(\mathbb{R}^{n+1},p)=F(\mathbb{R}^{n … For other manifolds $M$ such as $S^m$ and $S^m\times \mathbb{R}^k$ ($H^*F(\mathbb{R}^{n+1},p;\mathbb{Z}_p)$ is known in these cases), are there any results for the cohomology algebra $H^*(B(M,p);\mathbb …
3
votes
1
answer
196
views
group completion theorem by using homology fibrations
In the paper Homology fibrations and group completion theorem, McDuff-Segal (www.maths.ed.ac.uk/~aar/papers/mcdsegal.pdf), page 281:
Let $M$ be a topological monoid such that $\pi_0M$ is generated by …
1
vote
1
answer
171
views
Group completion of labelled configuration space on Euclidean spaces
In the lecture notes The Homology of $\mathcal{C}_{n+1}$-spaces, $n\geq 0$, F. Cohen, page 225 -226, it is obtained that there is a group completion on homology
$$
\alpha_n: C(\mathbb{R}^n;X)\to \Omeg …
2
votes
0
answers
198
views
cohomology ring of mapping spaces
Cohen, 1978, page 228-231, the cohomology ring
$$
H^*(\text{Map}_*(S^n, S^n\wedge X);\mathbb{Z}_p)
$$
is obtained for any primes $p\geq 2$. … Question: I want to know the cohomology ring
$$
H^*(\text{Map}_*(M, S^n);\mathbb{Z}_2)
$$
for some manifolds $M$ other than $S^n$, for example, $M=\mathbb{R}^n, \mathbb{R}P^n, \mathbb{C}P^n, \mathbb{T …
2
votes
0
answers
122
views
cohomology ring of cross-section space of one-point compactification of tangent bundle
Question: How to compute the cohomology ring
$$
H^*(\Gamma(\xi);\mathbb{Z}_2)?
$$
My attempt: I want to construct fibrations and use Serre spectral sequence. … Moreover, could the Serre spectral sequence give the explicit ring structure of
$$
H^*(\Gamma(\xi);\mathbb{Z}_2)
$$
completely, but not partial information about the cohomology? …
9
votes
1
answer
484
views
Steenrod operations on cohomology of grassmannians
Their cohomology rings are expressed in terms of universal Stiefel-Whitney classes
$$
H^*(G_k(\mathbb{R}^\infty);\mathbb{Z}_2)=\mathbb{Z}_2[w_1,w_2,\cdots,w_k],$$
$$
H^*(G_k(\mathbb{R}^n);\mathbb{Z}_2) … =\mathbb{Z}_2[w_1,w_2,\cdots,w_k]/(\bar w_{n-k+1},\bar w_{n-k+2}\cdots,\bar w_n).$$
What are the Steenrod operations $Sq^i$ on these cohomology rings? …
4
votes
1
answer
243
views
group completion theorem of homology as Hopf algebras
Let $M$ be a topological monoid with product $\mu$. Then $H_*(M)$ is a Hopf algebra with product $\mu_*$ and coproduct $\Delta_*$. The group-completion theorem by McDuff-Segal, 1976 gives that as a P …
10
votes
2
answers
1k
views
cup product and Steenrod operations in Serre spectral sequence
Suppose all differentials in the cohomology Serre spectral sequence (corresponding to the above fibration) are zero maps. … .
$$
Question 1: as cohomology rings with cup products, do we still have the isomorphism
$$
H^*(E)\cong H^*(F)\otimes H^*(B)? …
2
votes
1
answer
312
views
Kunneth formula of Cartesian product modulo orders of coordinates
Let $X$ be a topological space and $F$ a field. Let the $n$-th permutation group $\Sigma_n$ act on
$$
\prod_n X
$$
by
$$
\sigma(x_1,\cdots,x_n)=(x_{\sigma(1)},\cdots,x_{\sigma(n)}), \sigma\in \Sig …
9
votes
4
answers
1k
views
Examples of Stiefel-Whitney classes of manifolds
Let $M$ by an compact, connected $n$-dimensional manifold without boundary.
Are there any other computable examples of the Stiefel-Whitney class $w(M)$ except for $M=S^m, \mathbb{R}P^m,\mathbb{C}P^m, …
5
votes
0
answers
148
views
configuration space of Riemannian manifolds with a parameter on the distance of distinct points
Question: are there any references for the cohomology ring
$$
H^*(B(M,k,\epsilon);\mathbb{Z}_2)?
$$ …
12
votes
1
answer
822
views
Stiefel-Whitney class of fibre bundles
Or even in terms of the cohomology ring
$$
H^*(B;\mathbb{Z}_2), H^*(F;\mathbb{Z}_2)
$$
And other factors? …
3
votes
2
answers
595
views
mod p cohomology ring of alternating groups
What is the cohomology ring
$$
H^*(A_4;\mathbb{Z}/3)
$$
and its Steenrod operation $P^i$'s?
(2). … Are there general results about the cohomology ring
$$
H^*(A_{p+1};\mathbb{Z}/p)
$$
for general primes $p\geq 3$?
(3). …
13
votes
2
answers
891
views
References for Stiefel-Whitney class of Stiefel manifolds and Grassmannians
Let $M$ be a manifold. The total Stiefel-Whitney class of $M$ is defined to be the Stiefel-Whitney class of the tangent bundle $TM$
$$
w(M)=1+w_1(TM)+w_2(TM)+\cdots
$$
I want to find references for
$$ …
3
votes
1
answer
453
views
geometric conditions on maps between manifolds inducing monomorphisms on cohomology
Let $M,N$ be manifolds whose dimensions may be different. Let $f: M\longrightarrow N$ be a smooth map. What geometric conditions on $f$ can we impose such that the induced homomorphism
$$
f^*: H^*(N; …