MAYBE
Input TRS:
    1: f(x) -> a() | x --> a()
    2: f(x) -> b() | x --> b()
Infeasibility test:
    x --> a()
    x --> b()
Co-Order(NegReal,≥,Sum) ...Co-QLPOpS ...Co-QWPOpS(PosReal,>,Sum) ...Co-Order(PosReal,≥,Sum-Sum; PosReal,≥,Sum-Sum) ...failed.