theorem Satz6p28Lem02:
  for S being satisfying_Tarski-model TarskiGeometryStruct
  for a,b,c,d,e,f,g,h being Element of S st
  not c,d <= a,b & a,b equiv e,f & c,d equiv g,h holds
  e,f <= g,h
  proof
    let S be satisfying_Tarski-model TarskiGeometryStruct;
    let a,b,c,d,e,f,g,h be Element of S;
    a,b <= c,d or c,d <= a,b by Satz5p10;
    hence thesis by Satz5p6;
  end;
