(VAR x y z)
(RULES
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))
)
(COMMENT variant of hydra and hercules, see D33/33 )