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12
votes
Accepted
Why is $\pi_{-*}F(H\mathbb{F}_p, H\mathbb{F}_p)$ the mod $p$ Steenrod algebra?
Recall that by representability of cohomology plus the Yoneda lemma, a cohomology operation $H^i→H^j$ is the same thing as a map
$$ K(\mathbb{F}_p,i)→K(\mathbb{F}_p,j)\,.$$
Moreover, the suspension is …
18
votes
Steenrod operations in etale cohomology?
Your first map fits in an action of the Steenrod algebra.
In fact $H^*_{ét}(X;\mathbb{F}_2)$ is the homology of $C^*_{ét}(X;\mathbb{F}_2)=R\Gamma(X;\mathbb{F}_2)$, an element of the derived category …