for AS being AffinSpace for a, b, a9, b9, q being Element of AS for M, N being Subset of AS st q in M & q in N & a in M & a9 in M & b in N & b9 in N & q <> a & q <> b & M <> N & ( a,b // a9,b9 or b,a // b9,a9 ) & M is being_line & N is being_line & a = a9 holds b = b9