TORPAcyc is applied to the string rewriting system b b b -> a b a a -> a b a a a a -> a b b Tropical matrix interpretation interpretation of b: / 3 3 \ \ 0 2 / interpretation of a: / 2 0 \ \ 3 2 / remove rule 2 continue with: b b b -> a b a a a -> a b b interpretation of b: 2 interpretation of a: 3 remove rule 2 continue with: b b b -> a b interpretation of b: 10 interpretation of a: 6 remove rule 1 termination has been proved