The asymptotic spectrum of tensors and the exponent of matrix multiplication

Abstract

We introduce an asymptotic data structure for the relative bilinear complexity of bilinear maps (tensors). It consists of a compact Hausdorff space Δ together with an interpretation of the tensors under consideration as continuous functions on Δ. The asymptotic rank of a tensor is simply the maximum of the associated function. On the way we present a new method for estimating the exponent ω of matrix multiplication, leading at present to the bound ω ≪ 2.48. The paper gives only brief indications of proofs, if any. Detailed arguments may be found in 26,27.