0 QTRS
h(e(x), y) → h(d(x, y), s(y)) d(g(g(0, x), y), s(z)) → g(e(x), d(g(g(0, x), y), z)) d(g(g(0, x), y), 0) → e(y) d(g(0, x), y) → e(x) d(g(x, y), z) → g(d(x, z), e(y)) g(e(x), e(y)) → e(g(x, y))