MAYBE Proof: ConCon could not decide if this system is quasi-decreasing. \cite{O02}, p. 214, Proposition 7.2.50 does not apply. System R transformed to U(R). Call external tool: ttt2 - trs 30 Input: a -> c a -> d b -> c b -> d c -> e c -> l d -> m k -> l k -> m h(x, x) -> g(x, x, f(k)) g(d, x, x) -> A A -> h(f(a), f(b)) ?1(e, x) -> x f(x) -> ?1(x, x) The external tool could not decide termination.