Show simple item record

dc.contributor.authorGrimmett, Geoffreyen
dc.contributor.authorLi, Zhongyangen
dc.identifier.citationGrimmett et al. Contemporary Mathematics (2016)en
dc.description.abstractThe current paper is a short review of rigorous results for the 1-2 model. The 1-2 model on the hexagonal lattice is a model of statistical mechanics in which each vertex is constrained to have degree either 1 or 2. It was proposed in a study by Schwartz and Bruck of constrained coding systems, and is strongly connected to the dimer model on a decoration of the lattice, and to an enhanced Ising model and an associated polygon model on the graph derived from the hexagonal lattice by adding a further vertex in the middle of each edge. The general 1-2 model possesses three parameters a, b, c. The fundamental technique is to represent probabilities of interest as ratios of counts of dimer coverings of certain associated graphs, and to apply the Pfaffian method of Kasteleyn, Fisher, and Temperley. Of special interest is the existence (or not) of phase transitions. It turns out that all clusters of the infinite-volume limit are almost surely finite. On the other hand, the existence (with strictly positive probability) of infinite ‘homogeneous’ clusters, containing vertices of given type, depends on the values of the parameters. A further type of phase transition emerges in the study of the two-edge correlation function, and in this case the critical surface may be found explicitly. For instance, when a ≥ b ≥ c > 0, the surface given by √ a = √ b + √ c is critical.en
dc.publisherAmerican Mathematical Societyen
dc.rightsAttribution-NonCommercial-NoDerivs 2.0 UK: England & Wales
dc.subject1-2 modelen
dc.subjectpolygon modelen
dc.subjectIsing modelen
dc.subjectperfect matchingen
dc.subjectKasteleyn matrixen
dc.subjectphase transitionen
dc.titleThe 1-2 modelen
dc.typeBook chapter
prism.publicationNameIn the Tradition of Ahlfors–Bers, VIIen
dc.contributor.orcidGrimmett, Geoffrey [0000-0001-7646-3368]
rioxxterms.typeBook chapteren

Files in this item


This item appears in the following Collection(s)

Show simple item record

Attribution-NonCommercial-NoDerivs 2.0 UK: England & Wales
Except where otherwise noted, this item's licence is described as Attribution-NonCommercial-NoDerivs 2.0 UK: England & Wales