2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/57481I explain the two colored butterflies shown in figures 1 and 4, their thermodynamic significance and their duality.8 pages, 3 colored figures, 1 bw figure. Conference proceedings. An error in the statement of the Gibbs phase rule has been correctedMathematical PhysicsMesoscale and Nanoscale Physicstext