From Copying to Corelations via Ancestry Partitions
Abstract
We study the free PROP on a single binary generator . The ancestry functor , defined by connected components of the underlying undirected string diagram, has image the sub-PROP of finite corelations whose equivalence classes contain exactly one input and at least one output. The induced quotient [ \mathrm{AncQ}:=\mathrm{Syn}(\delta)/\ker(\Pi) ] is equivalent as a PROP to , the PROP for non-counital cocommutative comonoids. We then locate this primitive construction inside the standard cospan/corelation framework: realizes pushout-style gluing as a free hypergraph category; collapses under jointly epic corestriction to , the PROP for extraspecial commutative Frobenius monoids; and the Yoneda envelope [ \mathcal W=\mathrm{Fun}(\mathrm{FinCorel}^{op},\mathrm{Spc}) ] is a presheaf -topos carrying the standard subobject, modality, and monotone fixed-point apparatus. The PROP-level identification is the only result claimed as new; the remaining material is organizational and reduces explicitly to cited classical results.
Keywords
Cite
@article{arxiv.2505.22931,
title = {From Copying to Corelations via Ancestry Partitions},
author = {Andreu Ballus Santacana},
journal= {arXiv preprint arXiv:2505.22931},
year = {2026}
}
Comments
Substantially revised version. The previous version used a different categorical setup. The present version supersedes it for formal purposes and claims only the PROP-level identification $\mathrm{AncQ}\simeq \mathrm{Cocom}$ as new; the remaining material is organizational and reduced to cited classical results. 19 pages