let P be Subset of (TOP-REAL 2); :: thesis: ( (SW-corner P) `1 = (W-min P) `1 & (SW-corner P) `1 = (W-max P) `1 & (W-min P) `1 = (W-max P) `1 & (W-min P) `1 = (NW-corner P) `1 & (W-max P) `1 = (NW-corner P) `1 )
( (W-min P) `1 = W-bound P & (W-max P) `1 = W-bound P ) by EUCLID:52;
hence ( (SW-corner P) `1 = (W-min P) `1 & (SW-corner P) `1 = (W-max P) `1 & (W-min P) `1 = (W-max P) `1 & (W-min P) `1 = (NW-corner P) `1 & (W-max P) `1 = (NW-corner P) `1 ) by EUCLID:52; :: thesis: verum