Kleene 1938 second recursion theorem: every total computable f has fixed point e with phi_e = phi_{f(e)}; basis of self-reference + Goedel-fixed-point + virus quine constructions.
Kleene 1938 second recursion theorem: every total computable f has fixed point e with phi_e = phi_{f(e)}; basis of self-reference + Goedel-fixed-point + virus quine constructions.