,
Surabhi Chakrabartty
,
Ranveer Singh
Creative Commons Attribution 4.0 International license
The rank of an n × n matrix A is equal to the maximum order of a square submatrix with a nonzero determinant; it can be computed in O(n^{2.37}) time. Analogously, the maximum order of a square submatrix with nonzero permanent is defined as the permanental rank ρ_{per}(A). Computing the permanent or the coefficients of the permanental polynomial per(xI-A) is #P-complete. The permanental nullity η_{per}(A) is defined as the multiplicity of zero as a root of the permanental polynomial. We establish a permanental analog of the rank–nullity theorem, ρ_{per}(A) + η_{per}(A) = n for symmetric nonnegative matrices, positive semidefinite matrices, and adjacency matrices of balanced signed graphs. Using this theorem, we can compute the permanental nullity for these classes in polynomial time. For {0,± 1}-matrices, we also provide a complete characterization of when the permanental rank-nullity identity holds.
@InProceedings{pant_et_al:LIPIcs.STACS.2026.70,
author = {Pant, Priyanshu and Chakrabartty, Surabhi and Singh, Ranveer},
title = {{A Permanental Analog of the Rank-Nullity Theorem for Symmetric Matrices}},
booktitle = {43rd International Symposium on Theoretical Aspects of Computer Science (STACS 2026)},
pages = {70:1--70:12},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-412-3},
ISSN = {1868-8969},
year = {2026},
volume = {364},
editor = {Mahajan, Meena and Manea, Florin and McIver, Annabelle and Thắng, Nguy\~{ê}n Kim},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.STACS.2026.70},
URN = {urn:nbn:de:0030-drops-255590},
doi = {10.4230/LIPIcs.STACS.2026.70},
annote = {Keywords: permanent, matrix rank, #P-completeness, graph algorithms, permanental polynomial, spectral graph theory}
}