:: deftheorem Def6 defines 2-dimensional ANALOAF:def 6 :
for IT being OAffinSpace holds
( IT is 2-dimensional iff for a, b, c, d being Element of IT st not a,b // c,d & not a,b // d,c holds
ex p being Element of IT st
( ( a,b // a,p or a,b // p,a ) & ( c,d // c,p or c,d // p,c ) ) );