Cup product
= Cup product
{title2=$\smile$}
{wiki}
The cup product is a natural bilinear operation $H^p(X;R)\times H^q(X;R)\to H^{p+q}(X;R)$. It is graded-commutative: $a\smile b=(-1)^{pq}b\smile a$.
= Cup product
{title2=$\smile$}
{wiki}
The cup product is a natural bilinear operation $H^p(X;R)\times H^q(X;R)\to H^{p+q}(X;R)$. It is graded-commutative: $a\smile b=(-1)^{pq}b\smile a$.