theorem Th94:
  for TS1 being non empty transition-system over F1, TS2 being non
  empty transition-system over F2 st the carrier of TS1 = the carrier of TS2 &
  the Tran of TS1 = the Tran of TS2 holds x, y ==>* z, TS1 implies x, y ==>* z,
  TS2
by Th81;
