On Pentagon Equation, Tetrahedron Equation, Evolution and Integrals of Motion

There is a sub-class of the solutions to Quantum Tetrahedron Equation related to the algebraical Pentagon Equation. The Quantum Tetrahedron Equation defines an evolution operator in wholly discrete three dimensional space-time. In this paper we establish the Liouville integrability of one particular quantum evolution model/classical integrable model on cubic lattice. The key feature of the model is that it has two independent quantum/classical spectral curves. In particular, on the classical level its Hamiltonian equations of motion decouple into two independent Hirota equations.