Introduction to coherent spaces Arnold Neumaier Fakult¨at f¨ur Mathematik, Universit¨at Wien Oskar-Morgenstern-Platz 1, A-1090 Wien, Austria email:
[email protected] WWW: http://www.mat.univie.ac.at/~neum arXiv:1804.01402 September 28, 2018 Abstract. The notion of a coherent space is a nonlinear version of the notion of a complex Euclidean space: The vector space axioms are dropped while the notion of inner product is kept. Coherent spaces provide a setting for the study of geometry in a different direction than traditional metric, topological, and differential geometry. Just as it pays to study the properties of manifolds independently of their embedding into a Euclidean space, so it appears fruitful to study the properties of coherent spaces independent of their embedding into a Hilbert space. Coherent spaces have close relations to reproducing kernel Hilbert spaces, Fock spaces, and unitary group representations, and to many other fields of mathematics, statistics, and physics. This paper is the first of a series of papers and defines concepts and basic theorems about coherent spaces, associated vector spaces, and their topology. Later papers in the series dis- cuss symmetries of coherent spaces, relations to homogeneous spaces, the theory of group representations, C∗-algebras, hypergroups, finite geometry, and applications to quantum physics. While the applications to quantum physics were the main motiviation for develop- ing the theory, many more applications exist in complex analysis, group theory, probability theory, statistics, physics, and engineering. arXiv:1804.01402v2 [math-ph] 28 Sep 2018 For the discussion of questions concerning coherent spaces, please use the discussion forum https://www.physicsoverflow.org.