Knotted 4-regular graphs: polynomial invariants and the Pachner moves

Abstract

In loop quantum gravity, states of quantum geometry are represented by classes of knotted graphs, equivalent under diffeomorphisms. Thus, it is worthwhile to enumerate and distinguish these classes. This paper looks at the case of 4-regular graphs, which have an interpretation as objects dual to triangulations of three-dimensional manifolds. Two different polynomial invariants are developed to characterize these graphs -- one inspired by the Kauffman bracket relations, and the other based on quandles. How the latter invariant changes under the Pachner moves acting on the graphs is then studied.