Journal of Mathematical Modelling and Algorithms

, Volume 8, Issue 3, pp 335–342

A Note on Observables for Counting Trails and Paths in Graphs


DOI: 10.1007/s10852-009-9111-7

Cite this article as:
Markopoulou, F. & Severini, S. J Math Model Algor (2009) 8: 335. doi:10.1007/s10852-009-9111-7


We point out that the total number of trails and the total number of paths of given length, between two vertices of a simple undirected graph, are obtained as expectation values of specifically engineered quantum mechanical observables. Such observables are contextual with some background independent theories of gravity and emergent geometry. Thus, we point out yet another situation in which the mathematical formalism of a physical theory has some computational aspects involving intractable problems.


EnumerationPathsCyclesObservablesGraphity modelsGrassman variables

Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  1. 1.Perimeter Institute for Theoretical PhysicsWaterlooCanada
  2. 2.Institute for Quantum Computing and Department of Combinatorics & OptimizationUniversity of WaterlooWaterlooCanada