Heuristics for the Whitehead minimization problem.
Let be the multiplicative semigroup of all complex matrices, and let and be the –degree unitary group and general linear group over complex number field, respectively. We characterize group homomorphisms from to when or , and thereby determine multiplicative homomorphisms from to when or . This generalize Hochwald’s result in [Lin. Alg. Appl. 212/213:339-351(1994)]: if is a spectrum–preserving multiplicative homomorphism, then there exists a matrix in such that for...