2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/100601In this contribution we discuss the occurrence of first-order transitions in temperature in various short-range lattice models with a rotation symmetry. Such transitions turn out to be widespread under the condition that the interaction potentials are sufficiently nonlinear.Contribution to the Dublin John Lewis memorial meetingStatistical MechanicsMathematical Physicstext