ex V being non trivialRealLinearSpace ex u, v, w, u1 being Element of V st ( ( for a, b, c, d being Real st (((a * u)+(b * v))+(c * w))+(d * u1)=0. V holds ( a =0 & b =0 & c =0 & d =0 ) ) & ( for y being Element of V ex a, b, c, d being Real st y =(((a * u)+(b * v))+(c * w))+(d * u1) ) )