# Obtaining the subposet of dissectors of a poset

Following http://citeseerx.ist.psu.edu/viewdoc/... on page 3, the set of Dissectors Dis(P) of a poset P is defined as the subposet of P of elements x such that the order filter generated by x has a complement which is a principal order ideal. Is there an easy way to obtain this poset via Sage and calculate its width?