On the Hilbert-Samuel multiplicity of Fredholm tuples

Abstract

For commuting tuples R\in L(Z)^{n} of Banach-space operators that arise as quotients of lower semi-Fredholm systems T\in L(X)^{n} with constant cohomology dimension \textrm{dim}H^{n}(z-T,X) near the origin 0\in\mathbb{C}^{n}, we show that the Hilbert-Samuel multiplicity of R calculates the rank of the cohomology sheaf 0\in\mathbb{C}^{n}(z-R,\mathcal{O}_{\mathbb{C}^{n}}^{Z}) at z=0.