| Cic.Var (_, subst1), Cic.Var (_, subst2)
| Cic.Const (_, subst1), Cic.Const (_, subst2)
| Cic.MutInd (_, _, subst1), Cic.MutInd (_, _, subst2)
| Cic.MutConstruct (_, _, _, subst1), Cic.MutConstruct (_, _, _, subst2) ->
| Cic.Var (_, subst1), Cic.Var (_, subst2)
| Cic.Const (_, subst1), Cic.Const (_, subst2)
| Cic.MutInd (_, _, subst1), Cic.MutInd (_, _, subst2)
| Cic.MutConstruct (_, _, _, subst1), Cic.MutConstruct (_, _, _, subst2) ->