Chapter 4: Cohomology Operations

Let n, q be two integers and let π, G be two Abelian groups. We say that a cohomology operation\(\varphi\)of type (n, q, π, G) is given if for every CW complex X a map \(\varphi _{X}: H^{n}(X;\pi ) \rightarrow H^{q}(X;G)\) is given and is natural with respect to X, in the sense that the diagram