Resumen de A new characterization of the reduced minimum modulus of an operator on Banach spaces

Yifeng Xu

• Let X, Y be Banach spaces and let B(X; Y ) (resp. C(X; Y )) denote the set of all bounded (resp. nonzero densely de¯ned and closed) linear operators T from X (resp. (T)) to Y . We prove that the reduced minimum modulus (T) of T 2 C(X; Y ) is inffkAk j T $ (T +A); A 2 B(X; Y )g. Using this result, we give various esti