Section test.
Variables b' b2: nat.
Notation "n + m" := (n ▵ m) : my_scope.
Delimit Scope my_scope with my.
Notation l := 0.
Definition α := (0 + l)%my.
Definition a' b := b'++0++b2 _ ++x b.
Definition c := {True}+{True}.
Definition d := (1+2)%nat.

Lemma e : nat + nat.