theorem Th22:
for
V being
RealLinearSpace for
u,
u1,
v,
v1,
w,
y being
VECTOR of
V for
p,
p1,
q,
q1 being
Element of
(AMSpace (V,w,y)) st
p = u &
q = v &
p1 = u1 &
q1 = v1 holds
(
p,
q // p1,
q1 iff ex
a,
b being
Real st
(
a * (v - u) = b * (v1 - u1) & (
a <> 0 or
b <> 0 ) ) )