Section MapCanon.
Variable A : Type.
Inductive mapcanon : Map A -> Prop :=
| M0_canon : mapcanon (M0 A)
| M1_canon : forall (a:ad) (y:A), mapcanon (M1 A a y)
| M2_canon :
forall m1 m2:Map A,
mapcanon m1 ->
mapcanon m2 -> 2 <= MapCard A (M2 A m1 m2) -> mapcanon (M2 A m1 m2).

Lemma MapPut_behind_canon :
forall m:Map A,
mapcanon m -> forall (a:ad) (y:A), mapcanon (MapPut_behind A m a y).