theorem Th28: :: ANALMETR:28
for V being RealLinearSpace
for w, y being VECTOR of V
for p, p1, q, q1, r, r1 being Element of (AMSpace (V,w,y)) st Gen w,y & p,p1 _|_ q,q1 & p,p1 _|_ r,r1 & not p = p1 holds
q,q1 // r,r1