theorem Satz3p1: ::Bqaa
  for S being satisfying_CongruenceIdentity
              satisfying_SegmentConstruction
              TarskiGeometryStruct
  for a,b being POINT of S holds between a,b,b
  proof
    let S be satisfying_CongruenceIdentity
             satisfying_SegmentConstruction
             TarskiGeometryStruct;
    let a,b be POINT of S;
    ex x be POINT of S st between a,b,x & b,x equiv b,b by GTARSKI1:def 8;
    hence thesis by GTARSKI1:def 7;
  end;
