theorem ThMak4:
  for S being (TE) (SC) (FS') TarskiGeometryStruct holds
  (for a,b,c,d,e,f being POINT of S st
    a <> b & between b,a,c & between d,a,e &
    b,a equiv d,a & a,c equiv a,e & b,f equiv d,f
      holds
    f,c equiv e,f)
  proof
    let S be (TE) (SC) (FS') TarskiGeometryStruct;
    let a,b,c,d,e,f be POINT of S;
    assume
A1: a <> b & between b,a,c & between d,a,e &
      b,a equiv d,a & a,c equiv a,e & b,f equiv d,f;
A2: a,f equiv a,f by Satz2p1bis;
    S is (FS');
    hence thesis by A1,A2;
  end;
