Ltac normalize := repeat (auto with norm; normalize1).Definition mark {A: Type} (i: nat) (j: A) := j.

Lemma swap_mark0 {A} {NA: NatDed A}{SA: SepLog A}: forall i j (Pi Pj: A), (i<j)%nat -> mark i Pi * mark j Pj = mark j Pj * mark i Pi.