Reu 2013: the Cohomology of Groups

0 //K ⊂ //E q //Q //1. Here K stands for kernel and Q stands for quotient. She assumed that K is abelian (= commutative), so she wrote its product as + with identity element 0. She did not assume that Q is abelian, so she wrote its product as · with identity element 1. That explains the joke notation with 0 at the left and 1 at the right. The sequence is exact, which means that K is a normal subgroup of E with quotient group Q. She chose a set theoretic section t of q and found that g · k = t(g)kt(g)−1