Periodic Gibbs measures for the Potts model in translation-invariant and periodic external fields on the Cayley tree

Ground states and Gibbs measures of Ising model with competing interactions and an external field on a Cayley tree

“…One of the key problems related to the spin models is the description of the set of Gibbs measures (see [1], [3], [8], [11], [13], [18]). This problem has a good connection with the problem of the description the set of ground states.…”