2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/223122In this paper, we construct a new weakly universal cellular automaton on the ternary heptagrid. The previous result, obtained by the same author and Y. Song required six states only. This time, the number of states is four. This is the best result up to date for cellular automata in the hyperbolic plane.35 pages, 33 figuresFormal Languages and Automata TheoryComputational GeometryF.2.2text