An 11-Step Sorting Network for 18 Elements

Sorting networks are cost-effective multistage interconnection networks with sorting capabilities. These networks theoretically consume Θ(NlogN) comparisons. However, the fastest implementable sorting networks built so far consume Θ(Nlog2N) comparisons, and generally, use the Merge-sorting strategy to sort the input. An 18-element network using the Merge-sorting strategy needs at least 12 steps — here we show a network that sorts 18 elements in only 11 steps.