theorem Th4: :: change SCMFSA_2:98
  Exec(a := (f, bb), s).a = (s.f)/.|.s.bb.|
proof
  ex k being Nat st k = |.s.bb.| & Exec(a:=(f,bb), s).a = (s.f
  )/.k by SCMFSA_2:72;
  hence thesis;
end;
