Definition unit := DepMap dmDom_unit.Definition join : depmap := DepMap (dmDom_join (@pf dm1) (@pf dm2)).Definition valid (dm : depmap) := valid (dmap dm).Implicit Type f : depmap labF.Local Notation "f1 \+ f2" := (join f1 f2)
                               (at level 43, left associativity).Local Notation unit := (unit labF).

Lemma validU : valid unit.