theorem Th72:
  x, y -->. z, TS implies ==>.-relation(TS) reduces [x, y], [z, <%>E]
proof
  assume x, y -->. z, TS;
  then <*[x, y], [z, <%>E]*> is RedSequence of ==>.-relation(TS) by Th57;
  then [[x, y], [z, <%>E]] in ==>.-relation(TS) by Th8;
  hence thesis by REWRITE1:15;
end;
