activity
20062017
most citedLet's Expand Rota's Twelvefold Way For Counting Partitions!

3 citations · 6 across the 3 of their papers we have counts for

collaborators

7 papers

math.CO2017

Parabolic Catalan numbers count flagged Schur functions and their appearances as type A Demazure characters (key polynomials)

Robert A. Proctor, Matthew J. Willis

Fix an integer partition lambda that has no more than n parts. Let beta be a weakly increasing n-tuple with entries from {1,..,n}. The flagged Schur function indexed by lambda and…

math.CO2017

Convexity of tableau sets for type A Demazure characters (key polynomials), parabolic Catalan numbers

Robert A. Proctor, Matthew J. Willis

This is the first of three papers that develop structures which are counted by a "parabolic" generalization of Catalan numbers. Fix a subset R of {1,..,n-1}. Consider the ordered p…

math.CO2017

d-Complete posets: local structural axioms, properties, and equivalent definitions

Robert A. Proctor, Lindsey M. Scoppetta

Although d-complete posets arose along the interface between algebraic combinatorics and Lie theory, they are defined using only requirements on their local structure. These posets…

math.CO2017

Row bounds needed to justifiably express flagged Schur functions with Gessel-Viennot determinants

Robert A. Proctor, Matthew J. Willis

Let be a partition with no more than parts. Let be a weakly increasing -tuple with entries from . The flagged Schur function in the variables $x_1,…

math.CO2016★ 3 cited

Parabolic Catalan numbers count flagged Schur functions; Convexity of tableau sets for Demazure characters

Robert A. Proctor, Matthew J. Willis

Shuffles are n-multipermutations with suit multiplicities given by a subset R of {1,..,n-1}. Their inverses are ordered partitions of {1,..,n} whose block sizes derive from R. Thes…

math.CO2007

Distributive lattices defined for representations of rank two semisimple Lie algebras

L. Wyatt Alverson, Robert G. Donnelly, Scott J. Lewis +4

For a rank two root system and a pair of nonnegative integers, using only elementary combinatorics we construct two posets. The constructions are uniform across the root systems A1…