Module B.
Notation "{ x : A | P }" := (sigT (fun x:A => P)).
Notation "( x ; y )" := (existT _ x y).
Notation "p @ q" := (eq_trans p q) (at level 20).
Notation "p ^" := (eq_sym p) (at level 3).
Notation "p # x" := (transport _ p x) (right associativity, at level 65, only
parsing).
Definition ap {A B:Type} (f:A -> B) {x y:A} (p:x = y) : f x = f y
:= match p with eq_refl => eq_refl end.

Axiom transport_compose
: forall {A B} {x y : A} (P : B -> Type) (f : A -> B) (p : x = y) (z : P (f
x)),
transport (fun x => P (f x)) p z  =  transport P (ap f p) z.