Pontryagin cohomology operation explained

In mathematics, a Pontryagin cohomology operation is a cohomology operation taking cohomology classes in H²ⁿ(X,Z/p^rZ) to H^2pn(X,Z/p^r+1Z) for some prime number p. When p=2 these operations were introduced by and were named Pontrjagin squares by (with the term "Pontryagin square" also being used). They were generalized to arbitrary primes by .

See also

• Steenrod operation