(VAR x)
(RULES
  g(f(b,x)) -> g(h(h(f(f(h(k(k(x,x),x)),h(k(k(x,x),x))),h(k(k(x,x),x))))))
  f(x,b) -> h(f(f(x,x),x))
  k(x,b) -> f(x,b)
)
(COMMENT as #554, but with intermediate q elided, confluence of both should be the same)