Steenrod algebra
Algebraic topology / From Wikipedia, the free encyclopedia
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In algebraic topology, a Steenrod algebra was defined by Henri Cartan (1955) to be the algebra of stable cohomology operations for mod cohomology.
For a given prime number , the Steenrod algebra is the graded Hopf algebra over the field of order , consisting of all stable cohomology operations for mod cohomology. It is generated by the Steenrod squares introduced by Norman Steenrod (1947) for , and by the Steenrod reduced th powers introduced in Steenrod (1953a, 1953b) and the Bockstein homomorphism for .
The term "Steenrod algebra" is also sometimes used for the algebra of cohomology operations of a generalized cohomology theory.