MAYBE
Input TRS:
    1: f(x,y) -> g(x) | a() --> d()
    2: f(x,y) -> h(x) | b() --> d()
    3: g(s(x)) -> x
    4: h(s(x)) -> x
    5: a() -> d()
    6: b() -> d()
    7: e() -> e()
Infeasibility test:
    a() --> d()
    b() --> d()
Co-Order(NegReal,≥,Sum) ...Co-QLPOpS ...Co-QWPOpS(PosReal,>,Sum) ...Co-Order(PosReal,≥,Sum-Sum; PosReal,≥,Sum-Sum) ...failed.