Unconditional bases and fixed points of nonexpansive mappings
Unconditional bases and fixed points of nonexpansive mappings
We prove that every Banach space with a 1-unconditional basis has the fixed point property for nonexpansive mappings.In fact the argument works if the unconditional constant is < (v 7 ^ -3)/2.n EXAMPLE 1.The natural basis e n = (0,0,0,..., 1,0,...} is an unconditional basis in each of the spaces …