Paper 1, Section II, 18H
Part II, 2011
Let be a field.
(i) Let and be two finite extensions of . When the degrees of these two extensions are equal, show that every -homomorphism is an isomorphism. Give an example, with justification, of two finite extensions and of , which have the same degrees but are not isomorphic over .
(ii) Let be a finite extension of . Let and be two finite extensions of . Show that if and are isomorphic as extensions of then they are isomorphic as extensions of . Prove or disprove the converse.