In network theory, the Braunstein-Ghosh-Severini entropy12 (BGS entropy) of a network is the von Neumann entropy of a density matrix given by a normalized Laplacian matrix of the network. This definition of entropy does not have a clear thermodynamical interpretation. The BGS entropy has been used in the context of quantum gravity.3
- Samuel L. Braunstein, Sibasish Ghosh, Simone Severini, The laplacian of a graph as a density matrix: a basic combinatorial approach to separability of mixed states, Annals of Combinatorics, 10, No 3, 2006.
- Kartik Anand, Ginestra Bianconi, Entropy measures for networks: Toward an information theory of complex topologies, Phys. Rev. E 80, 045102(R) (2009).
- Carlo Rovelli, Francesca Vidotto, Single particle in quantum gravity and Braunstein-Ghosh-Severini entropy of a spin network, Phys. Rev. D 81, 044038 (2010).