How to use Serre spectral sequence to compute cup product structures?
Let $F\to E\to B$ be a fibration. Suppose all the differentials of the corresponding Serre spectral sequence of cohomology are zero. Can we obtain that for any field $k$, $$ H^*(E;k)\cong H^*(F;k)\otimes H^*(B,k) $$ as rings?
For example, how to solve the following problem?