Parity problem (source code)

= Parity problem
{wiki}

= Parity problem in sieve theory
{synonym}

Divisibility information by small primes cannot by itself reliably distinguish integers with an odd or even total number of prime factors. Consequently an upper-bound <Selberg sieve> can bound prime pairs and related sifted sets but does not supply a positive lower bound or the conjectured twin-prime asymptotic. This limitation concerns the information available to the sieve, not merely a choice of weight normalization.

// Target: number-theory.bigb