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: ?1(b, x) -> c f(x) -> ?1(a, x) g(x, x) -> g(f(a), f(b)) The external tool could not decide termination.