同濟大学 TONGJI UNIVERSITY Proof(finished) (di,e)is implied by (di,e),since di and dj, e;and e;are the same,(di,e)are equivalent. ●So are(e,f)and(d,f) (a,c)are implied by (di,f) (a,c)are equivalent.Proof (finished) ⚫(di , ei ) is implied by (dj , ej ), since di and dj , ei and ej are the same, (di , ei ) are equivalent. ⚫So are (ei , fi ) and (di , fi ) ⚫(a,c) are implied by (di , fi ) ⚫(a,c) are equivalent