| NCic.Meta (i,_), NCic.Meta (j,_) -> i-j
| NCic.Const r1, NCic.Const r2 -> NReference.compare r1 r2
| NCic.Appl l1, NCic.Appl l2 -> FoUtils.lexicograph compare l1 l2
| NCic.Meta (i,_), NCic.Meta (j,_) -> i-j
| NCic.Const r1, NCic.Const r2 -> NReference.compare r1 r2
| NCic.Appl l1, NCic.Appl l2 -> FoUtils.lexicograph compare l1 l2