reserve X,Z for set;
reserve x,y,z for object;
reserve A,B,C for Subset of X;

theorem
  for A being RelStr, B being Subset of A, s being FinSequence of A
    st s is B-desc_ordering holds
      the InternalRel of A is_connected_in B
proof
  let A be RelStr, B be Subset of A;
  let s be FinSequence of A;
  assume s is B-desc_ordering;
  then Rev(Rev(s)) is B-desc_ordering;
  then Rev(s) is B-asc_ordering by Th75;
  hence thesis by Th83;
end;
