Marked density under a permutation
= Marked density under a permutation
{title2=$p=K/N$}
For a <permutation> $f$ of an $N$-element set and a known marked output subset of size $K$, exactly $K$ inputs have marked outputs. The <uniform quantum superposition> thus has good probability $K/N$, independent of which permutation the oracle represents. This allows a known-angle <amplitude amplification> schedule without counting unknown preimages.