u3 U2 M={{vl,ul},{v2,u2},{v3,u3} M is a complete matching from Vi to v2, but it is not a complete matching from v2 to V1▪ M={{v1,u1},{v2,u2},{v3,u3}} ▪ M is a complete matching from V1 to V2, but it is not a complete matching from V2 to V1