Finite universal algebras can be described using XML tags understood by the Universal Algebra Calculator. This repository contains many examples of such files.
Citing files in this repository in publications requires some care because the contents of this repository change often. Nonetheless, it is possible to create accurate citations that point to files that existed at some point in time (but might no longer exist in the master branch). This is accomplished using releases and tags.
The DOI above is the concept DOI. It always resolves to the most recently archived version, so a citation that uses it does not go stale as the repository grows.
@misc{AlgebraFiles,
author = {William DeMeo and Ralph Freese},
title = {{UACalc} {A}lgebra{F}iles},
year = {2026},
doi = {10.5281/zenodo.595266},
url = {https://doi.org/10.5281/zenodo.595266},
note = {A repository of algebra files for the Universal Algebra
Calculator, \verb+https://github.com/UACalc/AlgebraFiles+.
The doi resolves to the most recently archived version.},
}
When it matters that a file had particular contents, cite the version DOI of a release rather than the concept DOI.
| Release | Date | Version DOI |
|---|---|---|
| v1.1.0 | September 2026 | 10.5281/zenodo.22739869 |
| v1.0.1 | May 2016 | 10.5281/zenodo.53936 |
| v1.0.0 | May 2016 | 10.5281/zenodo.53933 |
Note that the two 2016 releases contain no CongruenceLatReps directory,
which was first added in 2017, so neither is a useful citation for the
congruence lattice representations.
If you would like to add your own algebra (.ua) files to this repository so you can safely cite them in publications, you can either
(1) submit a pull request
OR
(2) email your algebra files to Ralph Freese or William DeMeo.
After you do (1) or (2), a new release and a corresponding BibTeX entry will be generated.
The contents of this repository are made available under the Creative Commons Attribution 4.0 International license: reuse them freely, and credit the authors.
For more information about UACalc and the algebra files, see uacalc.org/algfiles.
For questions, comments, or suggestions please submit an issue.