Maps Preserving Numerical Radius or Cross Norms of Products on 2×2 Matrix Algebras
Hou Jin-chuan · Journal of North University of China · 2009
Based on the accomplishments of corresponding issues when the space of dimension is greater than two,the paper mainly discusses nonlinear surjective maps preserving numerical radius or cross norms of matrix products on 2×2 matrix algebras.It is proved by using fundamental theorem of quantum mechanics,namely,Wigner's Theorem.All the maps are characterized completely and classified in order to improve the issues.