Section RClo.
Inductive rclo4 (clo: rel->rel) (r: rel): rel :=
| rclo4_base
x0 x1 x2 x3
(IN: r x0 x1 x2 x3):
@rclo4 clo r x0 x1 x2 x3
| rclo4_clo'
r' x0 x1 x2 x3
(LE: r' <4= rclo4 clo r)
(IN: clo r' x0 x1 x2 x3):
@rclo4 clo r x0 x1 x2 x3
.

Lemma rclo4_rclo clo r:
rclo4 clo (rclo4 clo r) <4= rclo4 clo r.