PreprintCC BY-NC-ND 4.0arXiv
Symmetric List Objects
Abstract
Cons-lists are fundamental to functional programming, and are well-understood as initial algebras, and as a concrete construction of free monoids. In category theory, such list objects can be axiomatised internal to any monoidal category, with nil and cons maps, and a recursion mechanism. When strengthened to support parametrised recursion, they can be shown to give the free monoid construction. We study a small variant on parametrised list objects called parametrised symmetric list objects, in a symmetric monoidal category, where the two frontmost elements are allowed to be permuted. We show that this gives a construction of free commutative monoids, and develop some related theory.
Related
BibTeX
@misc{blackett2026symmetric,
title = {{Symmetric List Objects}},
author = {Fiona Blackett and Vikraman Choudhury and Rin Liu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.37944},
eprint = {2610.37944},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.37944},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Symmetric List Objects
AU - Fiona Blackett
AU - Vikraman Choudhury
AU - Rin Liu
PY - 2026
DA - 2026/10/27
PB - arXiv
DO - 10.48550/arxiv.2610.37944
UR - https://arxiv.org/abs/2610.37944
AB - Cons-lists are fundamental to functional programming, and are well-understood as initial algebras, and as a concrete construction of free monoids. In category theory, such list objects can be axiomatised internal to any monoidal category, with nil and cons maps, and a recursion mechanism. When strengthened to support parametrised recursion, they can be shown to give the free monoid construction. We study a small variant on parametrised list objects called parametrised symmetric list objects, in a symmetric monoidal category, where the two frontmost elements are allowed to be permuted. We show that this gives a construction of free commutative monoids, and develop some related theory.
ER -