YES After renaming modulo { c->0, a->1, d->2, b->3 }, it remains to prove termination of the 6-rule system { 0 0 0 1 -> 2 2 , 2 3 -> 0 0 , 0 -> 1 1 1 1 , 2 -> 3 3 3 3 , 3 2 -> 0 0 , 1 0 0 0 -> 2 2 } 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 65 | | 0 1 | \ / 1 is interpreted by / \ | 1 16 | | 0 1 | \ / 2 is interpreted by / \ | 1 105 | | 0 1 | \ / 3 is interpreted by / \ | 1 26 | | 0 1 | \ / After renaming modulo { }, it remains to prove termination of the 0-rule system { } The system is trivially terminating.