The Pfaffian Structure of CFN Phylogenetic Networks

Fuente: arXiv
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Main Authors: Cummings, Joseph, Gross, Elizabeth, Hollering, Benjamin, Martin, Samuel, Nometa, Ikenna
Format: Preprint
Published: 2023
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_version_ 1866911176260059136
author Cummings, Joseph
Gross, Elizabeth
Hollering, Benjamin
Martin, Samuel
Nometa, Ikenna
author_facet Cummings, Joseph
Gross, Elizabeth
Hollering, Benjamin
Martin, Samuel
Nometa, Ikenna
contents Algebraic techniques in phylogenetics have historically been successful at proving identifiability results and have also led to novel reconstruction algorithms. In this paper, we study the ideal of phylogenetic invariants of the Cavender-Farris-Neyman (CFN) model on a phylogenetic network with the goal of providing a description of the invariants which is useful for network inference. It was previously shown that to characterize the invariants of any level-1 network, it suffices to understand all sunlet networks, which are those consisting of a single cycle with a leaf adjacent to each cycle vertex. We show that the parameterization of an affine open patch of the CFN sunlet model, which intersects the probability simplex, factors through the space of skew-symmetric matrices via Pfaffians. We then show that this affine patch is isomorphic to a determinantal variety and give an explicit Gr{ö}bner basis for the associated ideal, which involves only $\binom{n}{2}$ coordinates rather than $2^{n}$. Lastly, we show that sunlet networks with at least 6 leaves are identifiable using only these polynomials and run extensive simulations, which show that these polynomials can be used to accurately infer the correct network from DNA sequence data.
format Preprint
id arxiv_https___arxiv_org_abs_2312_07450
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle The Pfaffian Structure of CFN Phylogenetic Networks
Cummings, Joseph
Gross, Elizabeth
Hollering, Benjamin
Martin, Samuel
Nometa, Ikenna
Algebraic Geometry
Populations and Evolution
92B10, 62R01, 13P25
Algebraic techniques in phylogenetics have historically been successful at proving identifiability results and have also led to novel reconstruction algorithms. In this paper, we study the ideal of phylogenetic invariants of the Cavender-Farris-Neyman (CFN) model on a phylogenetic network with the goal of providing a description of the invariants which is useful for network inference. It was previously shown that to characterize the invariants of any level-1 network, it suffices to understand all sunlet networks, which are those consisting of a single cycle with a leaf adjacent to each cycle vertex. We show that the parameterization of an affine open patch of the CFN sunlet model, which intersects the probability simplex, factors through the space of skew-symmetric matrices via Pfaffians. We then show that this affine patch is isomorphic to a determinantal variety and give an explicit Gr{ö}bner basis for the associated ideal, which involves only $\binom{n}{2}$ coordinates rather than $2^{n}$. Lastly, we show that sunlet networks with at least 6 leaves are identifiable using only these polynomials and run extensive simulations, which show that these polynomials can be used to accurately infer the correct network from DNA sequence data.
title The Pfaffian Structure of CFN Phylogenetic Networks
topic Algebraic Geometry
Populations and Evolution
92B10, 62R01, 13P25
url https://arxiv.org/abs/2312.07450