The variety generated by order algebras

Every ordered set can be considered as an algebra in a natural way. We investigate the variety generated by order algebras. We prove, among other things, that this variety is not finitely based and, although locally finite, it is not contained in any finitely generated variety; we describe the bottom of the lattice of its subvarieties

On The Relational Width of First-Order Expansions of Finitely Bounded Homogeneous Binary Cores with Bounded Strict Width

The relational width of a finite structure, if bounded, is always (1,1) or (2,3). In this paper we study the relational width of first-order expansions of finitely bounded homogeneous binary cores where binary cores are structures with equality and some anti-reflexive binary relations such that for any two different elements a, b in the domain there is exactly one binary relation R with (a, b) in R. Our main result is that first-order expansions of liberal finitely bounded homogeneous binary cores with bounded strict width have relational width (2, MaxBound) where MaxBound is the size of the largest forbidden substructure, but is not less than 3, and liberal stands for structures that do not forbid certain finite structures of small size. This result is built on a new approach and concerns a broad class of structures including reducts of homogeneous digraphs for which the CSP complexity classification has not yet been obtained.Comment: A long version of an extended abstract that appeared in LICS 202

Automatic enumeration of regular objects

We describe a framework for systematic enumeration of families combinatorial structures which possess a certain regularity. More precisely, we describe how to obtain the differential equations satisfied by their generating series. These differential equations are then used to determine the initial counting sequence and for asymptotic analysis. The key tool is the scalar product for symmetric functions and that this operation preserves D-finiteness.Comment: Corrected for readability; To appear in the Journal of Integer Sequence

TOURNAMENTS, RISK PERCEPTIONS, AND FAIRNESS

This paper reports the results of an economic experiment investigating human subjects' preferences for two types of contracts tournaments and fixed performance standard contracts. Willingness to pay data was elicited through an auction and results suggest that subjects prefer fixed performance standard contracts to tournaments. Primary drivers of this result appear to be subjects' perceptions that tournaments are more risky and less fair than fixed performance standard contracts. Surprisingly, measures of the relative profitability of the contracts did not correlate with willingness to pay. Our results can shed light on why agricultural producers express frustration over tournaments and can provide insights on contract and policy design.Research Methods/ Statistical Methods,

AJAE Appendix: Tournaments, Fairness, and Risk

The material contained herein is supplementary to the article named in the title and published in the American Journal of Agricultural Economics, Volume 88, Number 3, August 2006.Research Methods/ Statistical Methods, Risk and Uncertainty,