5 papers
An analogue of distributivity for ungraded lattices
Hugh Thomas
In this paper, we define a property, trimness, for lattices. Trimness is a not-necessarily-graded generalization of distributivity; in particular, if a lattice is trim and graded,…
Peg Jumping for Fun and Profit
David M. Bradley, Hugh Thomas
We consider the problem of determining the minimum number of moves needed to solve a certain one-dimensional peg puzzle. Let N be a positive integer. The puzzle apparatus consists…
Graded left modular lattices are supersolvable
Hugh Thomas
We provide a direct proof that a finite graded lattice with a maximal chain of left modular elements is supersolvable. This result was first established via a detour through EL-lab…
Tamari lattices and noncrossing partitions in type B and beyond
Hugh Thomas
The usual, or type A_n, Tamari lattice is a partial order on T_n^A, the triangulations of an (n+3)-gon. We define a partial order on T_n^B, the set of centrally symmetric triangula…
Cycles representing the Todd class of a toric variety
James Pommersheim, Hugh Thomas
In this paper, we describe a way to construct cycles which represent the Todd class of a toric variety. Given a lattice with an inner product we assign a rational number m(s) to ea…