theorem Satz3p13:
  for S being satisfying_CongruenceIdentity
              satisfying_SegmentConstruction
              satisfying_Lower_Dimension_Axiom
              TarskiGeometryStruct holds
  ex a,b,c being POINT of S st not between a,b,c &
  not between b,c,a & not between c,a,b & a <> b & b <> c & c <> a
  proof
    let S be satisfying_CongruenceIdentity
             satisfying_SegmentConstruction
             satisfying_Lower_Dimension_Axiom
             TarskiGeometryStruct;
    consider a,b,c be POINT of S such that
A1: not between a,b,c & not between b,c,a & not between c,a,b
      by GTARSKI2:def 7;
    take a,b,c;
    thus thesis by A1,Satz3p1;
  end;
