theorem Th11:
  a <> cc implies StepForUp(a,bb,cc,I,p,s).0.cc = s.cc
proof
  set aux = 1-stRWNotIn ({a, bb, cc} \/ UsedILoc I);
  set S = s+*(aux, s.cc-s.bb+1)+*(a, s.bb);
  cc in {a, bb, cc} by ENUMSET1:def 1;
  then cc in {a, bb, cc} \/ UsedILoc I by XBOOLE_0:def 3;
  then
A1: cc <> aux by SCMFSA_M:25;
  assume a <> cc;
  then S.cc = (s+*(aux, s.cc-s.bb+1)).cc by FUNCT_7:32
    .= s.cc by A1,FUNCT_7:32;
  hence thesis by SCMFSA_9:def 5;
end;
