Immerman–Szelepcsényi theorem

The set of Immerman and Szelepcsényi is a set of complexity theory and stating that the class NL is closed under complementation.

Long as it was assumed for the class NTIME that NL is not closed under the complement, to 1988 Immerman and Szelepcsényi independently providing evidence.

Formal definition

Be a platzkonstruierbare function. Then:

Evidence

The proof uses the technique of proof of interactive non-deterministic counting.