Linear Extensions and Comparable Pairs in Partial Orders

Abstract

We study the number of linear extensions of a partial order with a given proportion of comparable pairs of elements, and estimate the maximum and minimum possible numbers. We also consider a random interval partial order on $n$ elements, which has close to a third of the pairs comparable with high probability: we show that the number of linear extensions is $n!2^{-\Theta (n)}$ with high probability.

Authors' accepted manuscript, 20 pages