Boolean Sums of Operators and Projection Constants
This paper considers Boolean sums of projections and their norms. If A and Β are operators with suitable ranges and domains, then their Boolean sum is the operator A + Β AB. In particular we consider the equation | |A + Β — AB\\ = Mil + l|£|| + U\\\\B\\ änd show that this equality is not achievable in a uniformly convex Banach space when A + Β — AB is also a projection. AMS 1980 Classification 41A65