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Matrix Completion Discriminants
Abstract
We introduce the matrix completion discriminant of a graph as the Zariski closure of the set of partial symmetric matrices whose completion fibers fail to meet a rank stratum transversely. A clique-sum formula for the matrix completion discriminant is established for arbitrary graphs, while explicit defining equations for cycles are obtained in terms of iterated resultants. Using these results together with the analysis of K4-minor-free graphs, we prove that for every cycle-completable graph, the discriminant factors into determinant factors from maximal cliques and resultant factors from chordless cycles.
Related
BibTeX
@misc{sekiguchi2026matrix,
title = {{Matrix Completion Discriminants}},
author = {Yoshiyuki Sekiguchi and Shin-ichi Tanigawa},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.21341},
eprint = {2610.21341},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.21341},
}
RIS
TY - UNPB
TI - Matrix Completion Discriminants
AU - Yoshiyuki Sekiguchi
AU - Shin-ichi Tanigawa
PY - 2026
DA - 2026/10/15
PB - arXiv
DO - 10.48550/arxiv.2610.21341
UR - https://arxiv.org/abs/2610.21341
AB - We introduce the matrix completion discriminant of a graph as the Zariski closure of the set of partial symmetric matrices whose completion fibers fail to meet a rank stratum transversely. A clique-sum formula for the matrix completion discriminant is established for arbitrary graphs, while explicit defining equations for cycles are obtained in terms of iterated resultants. Using these results together with the analysis of K_4-minor-free graphs, we prove that for every cycle-completable graph, the discriminant factors into determinant factors from maximal cliques and resultant factors from chordless cycles.
ER -