TORPAcyc is applied to the string rewriting system a a a -> b b b -> a a a a -> a b a Tropical matrix interpretation interpretation of a: / 1 2 \ \ 0 1 / interpretation of b: / 3 0 \ \ 2 3 / remove rule 3 continue with: a a a -> b b b -> a a interpretation of a: 1 interpretation of b: 3 remove rule 2 continue with: a a a -> b interpretation of a: 1 interpretation of b: 0 remove rule 1 termination has been proved