All Questions
Tagged with cup-product steenrod-algebra
4 questions
7
votes
1
answer
179
views
Generalisation of Hirsch formula for the associativity of Steenrod's higher $\cup_2$ product with $\cup_1$ and cup products
For $f$, $g$ and $h$ cochains, the Hirsch formula is given as
$$ (f\cup g)\cup_1 h=f\cup (g\cup_1 h)+(-1)^{q(r-1)}(f\cup_1 h)\cup g.$$
Is there a more general formula that relates the associativity of ...
4
votes
0
answers
120
views
Is there a local simplicial formula for the Steenrod squares which commutes with the derivative on cochain level?
There is a well-known formula for the cup product of an $i$-cochain $A$ and $j$-cochain $B$ in simplicial homology given by
$$(A\cup B)(0\ldots i+j) = A(0\ldots i) B(0\ldots j)\;.$$
This formula ...
3
votes
1
answer
215
views
Cartan Formula for Steenrod square on cocycles
Let $x_n,y_n,\cdots$ be cocycles in $Z^n(X,\mathbb{Z}_2)$ (not cohomology classes in $H^n(X,\mathbb{Z}_2)$).
Let $Sq^k(x)\equiv x_n \cup_{n-k} x_n$ be the Steenrod square (This definition is valid for ...
5
votes
2
answers
2k
views
Why are cup-i products and Steenrod Squares often (always?) unary?
One way to define the Steenrod Operations is to use the cup-i product, as in Mosher and Tangora's book. It basically says, given the chain complex from mod-2 homology $C_\ast$, define
$D_0 : C_\ast\...