take [*(+ (x1,y1)),(+ (x2,y2))*] ; :: thesis: ex x1, x2, y1, y2 being Element of REAL st
( x = [*x1,x2*] & y = [*y1,y2*] & [*(+ (x1,y1)),(+ (x2,y2))*] = [*(+ (x1,y1)),(+ (x2,y2))*] )
thus ex x1, x2, y1, y2 being Element of REAL st
( x = [*x1,x2*] & y = [*y1,y2*] & [*(+ (x1,y1)),(+ (x2,y2))*] = [*(+ (x1,y1)),(+ (x2,y2))*] ) by A2, A4; :: thesis: verum