156 citations · 333 across the 5 of their papers we have counts for
9 papers
The Ponzano-Regge model and Reidemeister torsion
John W. Barrett, Ileana Naish-Guzman
The Ponzano-Regge model of three-dimensional quantum gravity is well-defined when the observables satisfy a certain condition involving the twisted cohomology. In this case, the pa…
Sandpiles and superconductors: dual variational formulations for critical-state problems
John W. Barrett, Leonid Prigozhin
Similar evolutionary variational inequalities appear as convenient formulations for continuous models for sandpile growth, magnetization of type-II superconductors, and evolution o…
Categorical representations of categorical groups
John W. Barrett, Marco Mackaay
The representation theory for categorical groups is constructed. Each categorical group determines a monoidal bicategory of representations. Typically, these categories contain rep…
Refractive gravitational waves and quantum fluctuations
John W. Barrett
Refractive gravitational waves are a generalisation of impulsive waves on a null hypersurface in which the metric is discontinuous but a weaker continuity condition for areas holds…
State sum models for quantum gravity
John W. Barrett
This paper reviews the construction of quantum field theory on a 4-dimensional spacetime by combinatorial methods, and discusses the recent developments in the direction of a combi…
Unlinked Embedded Graphs
John W. Barrett
This paper is a self-contained development of an invariant of graphs embedded in three-dimensional Euclidean space using the Jones polynomial and skein theory. Some examples of the…