theorem
  p=h.x & q=h.y & not x in still_not-bound_in h & not y in
  still_not-bound_in p implies All(x,p) => All(y,q) is valid
proof
  assume p=h.x & q=h.y & not x in still_not-bound_in h & not y in
  still_not-bound_in p;
  then ( not y in still_not-bound_in All(x,p))& All(x,p) => q is valid by Th5
,Th25;
  hence thesis by CQC_THE1:67;
end;
