Chapel Hill Poset Atlas

Cheryl A. Gann and Robert A. Proctor

August 3, 2005

Data Contents

This site contains lists of the following kinds of posets with up to m elements:
m=9: Unlabeled posets, connected posets, and posets with unique maximal elements.
m=9: Connected hook length posets and indecomposable disconnected hook length posets.
m=9: Connected d-complete and connected jeu de taquin posets.
m=7: Naturally labeled posets and hook length posets.

The following data is listed for posets with up to 7 elements:
Inverse order extensions, isomorphisms from natural labellings to standard forms, and name lookups for standard forms.

Features

* Concise easily human-readable data structure for each poset.
* Each poset is expressed in a unique standard form.
* Posets are easily readably listed in a standard order, one poset per line.
* Direct web access to individual data files: preview and download only those you want.
* Data in Mathematica form, and should be easily convertible to other forms.
* Auxiliary data for fast isomorphism and order extension computations.
* Carefully checked data.
* The Mathematica programs used to generate this data may be downloaded.

Table of Contents

Poset Definitions
Poset Counts
Data Structure for Posets
Standard Forms for Posets & Standard Ordering of Standard Forms
Definitions for Associated Data Files

Access to Poset List Files and Associated Data Files

Cheryl Gann's 2005 UNC-CH Masters Project
Access to Program Files

This site is maintained (Maintenance Log) by Bob Proctor: rap =at= email.unc.edu.
(His Home Page at Separate Website. )
This site builds upon work done by David M. Behrman and Sarah Wilmesmeier Bergmann in their 1996-97 UNC Masters projects.

Please cite this site! (If it was helpful for your research.)
[*] C.A. Gann and R.A. Proctor, Chapel Hill Poset Atlas,
published electronically at http://www.unc.edu/~rap/Posets, v 1.0, July 2005.

John Stembridge has posted a poset computational package which consists of 33 Maple programs. It also contains some lists of posets and lattices, some of which we have used to check our work:
John Stembridge's Packages Home Page

Curtis Greene, et. al., have posted a poset computational package consisting of many Mathematica programs:
Curtis Greene's Poset Packages Page