A new matching property for posets and existence of disjoint chains

Mark J. Logan, Shahriar Shahriari

    Research output: Contribution to journalArticlepeer-review

    4 Scopus citations

    Abstract

    Let P be a graded poset. Assume that x1,...,xm are elements of rank k and y1,...,ym are elements of rank l for some k<l. Further suppose xi≤yi, for 1≤i≤m. Lehman and Ron (J. Combin. Theory Ser. A 94 (2001) 399) proved that, if P is the subset lattice, then there exist m disjoint skipless chains in P that begin with the x's and end at the y's. One complication is that it may not be possible to have the chains respect the original matching and hence, in the constructed set of chains, xi and yi may not be in the same chain. In this paper, by introducing a new matching property for posets, called shadow-matching, we show that the same property holds for a much larger class of posets including the divisor lattice, the subspace lattice, the lattice of partitions of a finite set, the intersection poset of a central hyperplane arrangement, the face lattice of a convex polytope, the lattice of noncrossing partitions, and any geometric lattice.

    Original languageEnglish (US)
    Pages (from-to)77-87
    Number of pages11
    JournalJournal of Combinatorial Theory. Series A
    Volume108
    Issue number1
    DOIs
    StatePublished - Oct 2004

    Keywords

    • Boolean lattice
    • Disjoint chains
    • Geometric lattice
    • Matching property
    • Noncrossing partitions
    • Shadow-matching

    Fingerprint Dive into the research topics of 'A new matching property for posets and existence of disjoint chains'. Together they form a unique fingerprint.

    Cite this