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Complexity and geometry of bilinear maps. (Komplexität und Geometrie bilinearer Abbildungen.) (German. English summary) Zbl 1094.12003

This is the written exposition of a talk for a general mathematical audience, held by the author at the DMV-meeting. Complexity and degeneration of bilinear maps may be described by a single data structure: the asymptotic spectrum. The paper gives an introduction to this theory. As a red thread it uses \(\omega\), the exponent of matrix multiplication. The paper has been supplemented by footnotes containing more details and by an appendix, which is an invitation to application-oriented algebraists and geometers to be become acquainted with the topic. It contains short new proofs for some results in the main text, conjectures, and relations to other topics.

MSC:

12Y05 Computational aspects of field theory and polynomials (MSC2010)
68W30 Symbolic computation and algebraic computation
14L24 Geometric invariant theory
15A69 Multilinear algebra, tensor calculus
53D20 Momentum maps; symplectic reduction
65Y20 Complexity and performance of numerical algorithms
68Q17 Computational difficulty of problems (lower bounds, completeness, difficulty of approximation, etc.)