1 | 17. u: Term 18. v: Term List 19. xx:Top.
reduce( t,vs. term_free_vars(t) @ vs;nil;v) = nil

(list_accum(x,t.x([[t]] 1of(e) s a2 tr);xx;v) ~ list_accum(x,t.x([[t]] 1of(e) s a1 tr);xx;v)) xx:Top. (term_free_vars(u) @ reduce( t,vs. term_free_vars(t) @ vs;nil;v)) = nil  (list_accum(x,t.x([[t]] 1of(e) s a2 tr);xx([[u]] 1of(e) s a2 tr);v) ~ list_accum(x,t.x([[t]] 1of(e) s a1 tr);xx([[u]] 1of(e) s a1 tr);v)) |