 The fixed point theorem demonstrates—to some extent—the expressive power of CL. However, fixed point combinators may be defined from bases without a cancellator (as \(\textsf{Y}_1\) and \(\textsf{Y}_2\) show). The full power of CL (with the base \(\{\textsf{S},\textsf{K}\}\)) is enunciated by the following theorem.