fact: Definition prod2 (A1 A2:Type) (R1:binary A1) (R2:binary A2) : binary (A1*A2) := fun p1 p2 : A1*A2 => match p1,p2 with (x1,x2),(y1,y2) => R1 x1 y1 /\ R2 x2 y2 end.
imports: TLC(LibTactics LibLogic LibBool LibLogic LibProd LibSum)