The groupoidal picture of quantum mechanics

The basic ingredients of the groupoid interpretation of Quantum Mechanics are discussed. Starting with the motivation to consider measure groupoids as the appropriate statistical and kinematical setting to describe quantum mechanical systems, the algebra of observables of the system is constructed as the von Neumann algebra of the groupoid. The interpretation of the theory for classical systems is briefly analysed. As a final application of these ideas, Feynman's sum-over-histories interpretation of the theory is discussed in the groupoid picture. (c) 2024 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons .org /licenses /by-nc -nd /4 .0/).