fact: Definition prod_family I A1 A2 (F1:family I A1) (F2:family I A2) := prod_family_sim (family_r F1) (family_sim F1) (family_sim F2).
imports: TLC(LibTactics LibLogic LibReflect LibEpsilon LibInt LibProd LibSum LibOperation LibRelation LibWf LibOrder LibMin)