54 citations · 54 across the 2 of their papers we have counts for
8 papers
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…
The Quantum Tetrahedron in 3 and 4 Dimensions
John C. Baez, John W. Barrett
Recent work on state sum models of quantum gravity in 3 and 4 dimensions has led to interest in the `quantum tetrahedron'. Starting with a classical phase space whose points corres…