摘要
This letter generalizes the main theorem of petryshyn given in (J. Math. Anal. Appl., 39 (1972), 717—741)Theorem 1. Let T:X→ X be a 1-set-contraction such that (I—T)((?)(0, r)) is closed for each r > 0. Suppose that the following conditions are satisfied:
基金
Project supported by the Science Fund of Academia Sinica
