YES After renaming modulo { b->0, c->1, d->2, a->3 }, it remains to prove termination of the 5-rule system { 0 0 -> 1 2 , 1 1 -> 2 2 2 , 2 2 2 -> 3 1 , 3 3 ->= 0 1 , 0 1 ->= 3 3 } The system was filtered by the following matrix interpretation of type E_J with J = {1,...,2} and dimension 2: 0 is interpreted by / \ | 1 22 | | 0 1 | \ / 1 is interpreted by / \ | 1 26 | | 0 1 | \ / 2 is interpreted by / \ | 1 17 | | 0 1 | \ / 3 is interpreted by / \ | 1 24 | | 0 1 | \ / After renaming modulo { 3->0, 0->1, 1->2 }, it remains to prove termination of the 2-rule system { 0 0 ->= 1 2 , 1 2 ->= 0 0 } The system is trivially terminating.