:: deftheorem defines Vebleian INCPROJ:def 8 :
for S being IncProjStr holds
( S is Vebleian iff for a, b, c, d, p, q being POINT of S
for M, N, P, Q being LINE of S st a on M & b on M & c on N & d on N & p on M & p on N & a on P & c on P & b on Q & d on Q & not p on P & not p on Q & M <> N holds
ex q being POINT of S st
( q on P & q on Q ) );