reserve V for RealLinearSpace;
reserve p,q,u,v,w,y for VECTOR of V;
reserve a,b,c,d for Real;
reserve AS for non empty AffinStruct;
reserve a,b,c,d for Element of AS;
reserve x,z for object;

theorem
  (ex a,b being Element of AS st a<>b) & (for a,b,c,d,p,q,r,s being
Element of AS holds a,b // c,c & (a,b // b,a implies a=b) & (a<>b & a,b // p,q
& a,b // r,s implies p,q // r,s) & (a,b // c,d implies b,a // d,c) & (a,b // b,
c implies a,b // a,c) & (a,b // a,c implies a,b // b,c or a,c // c,b)) & (ex a,
  b,c,d being Element of AS st not a,b // c,d & not a,b // d,c) & (for a,b,c
being Element of AS ex d being Element of AS st a,b // c,d & a,c // b,d & b<>d)
  & (for p,a,b,c being Element of AS st p<>b & b,p // p,c ex d being Element of
AS st a,p // p,d & a,b // c,d) & (for a,b,c,d being Element of AS st not a,b //
c,d & not a,b // d,c holds ex p being Element of AS st (a,b // a,p or a,b // p,
  a) & (c,d // c,p or c,d // p,c)) iff AS is OAffinPlane by Def5,Def6,
