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Maximal Chain Descent Orders

Stephen Lacina, University of Oregon
Wednesday, October 5, 2022 - 3:30pm to 5:00pm
PDL C-38 and via Zoom Link:
Stephen Lacina
Stephen Lacina


We introduce a partial order called the maximal chain descent order on the maximal chains of a finite, bounded poset with an EL-labeling. We prove that the maximal chain descent order encodes via its linear extensions all shellings of the order complex induced by the EL-labeling strictly including the well known lexicographic shellings. We show that the standard EL-labeling of the Boolean lattice has maximal chain descent order isomorphic to the type A weak order. We also prove that natural EL-labelings of intervals in Young's lattice give maximal chain descent orders isomorphic to partial orders on the standard Young tableaux or standard skew tableaux of a fixed shape given swapping by certain entries. We also show that the cover relations of maximal chain descent orders are generally more subtle than one might first expect, but we characterize the EL-labelings with the expected cover relations including many well known families of EL-labelings.

Note: This talk begins with a pre-seminar (aimed at graduate students) at 3:30–4:00. The main talk starts at 4:10.

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Meeting ID: 915 4733 5974