0 QTRS
h(x, x) → h(a, b) g(g(x, a), y) → g(g(a, y), g(a, x)) f(g(x, y)) → g(g(f(f(y)), h(a, a)), x) h(h(f(f(x)), y), h(z, v)) → h(h(f(z), f(f(f(y)))), h(v, x))