:: deftheorem defines satisfying_DES_2 AFF_2:def 6 :
for AP being AffinPlane holds
( AP is satisfying_DES_2 iff for A, P, C being Subset of AP
for o, a, b, c, a9, b9, c9 being Element of AP st o in A & o in P & o in C & o <> a & o <> b & o <> c & a in A & a9 in A & b in P & b9 in P & c in C & A is being_line & P is being_line & C is being_line & A <> P & A <> C & a,b // a9,b9 & a,c // a9,c9 & b,c // b9,c9 holds
c9 in C );