There are two projection functions: π 1 {\displaystyle \pi _{1}} preserves the input tape, and π 2 {\displaystyle \pi _{2}} preserves the output tape.
Postoje dvije funkcije projekcije: π 1 {\displaystyle \pi _{1}} čuva ulaznu traku, i π 2 {\displaystyle \pi _{2}} čuva izlaznu traku.