Alternating sign matrix: Difference between revisions

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In [[mathematics]], an '''alternating sign matrix''' is a [[square matrix]] of 0s, 1s, and −1s such that the sum of each row and column is 1 and the nonzero entries in each row and column alternate in sign. These matrices generalize [[Permutation matrix|permutation matrices]] and arise naturally when using [[Dodgson condensation]] to compute a determinant.<ref>{{cn|reason=This is not described in the linked article|date=April 2021}} They are also closely related to the [[six-vertex model]] with ___domain wall boundary conditions from [[statistical mechanics]]. They were first defined by William Mills, [[David P. Robbins|David Robbins]], and Howard Rumsey in the former context.citation

| last = Hone | first = Andrew N. W.

| doi = 10.1098/rsta.2006.1887

| issue = 1849

| journal = Philosophical Transactions of the Royal Society of London

| mr = 2317901

| pages = 3183–3198

| title = Dodgson condensation, alternating signs and square ice

| volume = 364

| year = 2006| bibcode = 2006RSPTA.364.3183H

}}</ref> They are also closely related to the [[six-vertex model]] with ___domain wall boundary conditions from [[statistical mechanics]]. They were first defined by William Mills, [[David P. Robbins|David Robbins]], and Howard Rumsey in the former context.

==Examples==

A [[permutation matrix]] is an alternating sign matrix, and an alternating sign matrix is a permutation matrix if and only if no entry equals {{math|−1}}.

An example of an alternating sign matrix that is not a permutation matrix is

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:1, 1, 2, 7, 42, 429, 7436, 218348, … {{OEIS|id=A005130}}.

This theorem was first proved by [[Doron Zeilberger]] in 1992.<ref>Zeilberger, Doron, [http://www.combinatorics.org/Volume_3/Abstracts/v3i2r13.html "Proof of the alternating sign matrix conjecture"], ''[http://www.combinatorics.org/ Electronic Journal of Combinatorics]'' 3 (1996), R13.</ref> In 1995, [[Greg Kuperberg]] gave a short proof<ref>[[Greg Kuperberg|Kuperberg, Greg]], [http://frontarxiv.math.ucdavis.eduorg/abs/math.CO/9712207 "Another proof of the alternating sign matrix conjecture"], ''International Mathematics Research Notes'' (1996), 139-150.</ref> based on the [[Yang–Baxter equation]] for the six-vertex model with ___domain-wall boundary conditions, that uses a determinant calculation due to Anatoli Izergin.<ref>"Determinant formula for the six-vertex model", A. G. Izergin et al. 1992 ''J. Phys. A'': Math. Gen. 25 4315.</ref> In 2005, a third proof was given by [[Ilse Fischer]] using what is called the ''operator method''.<ref>{{Cite journal|last=Fischer|first=Ilse|title=A new proof of the refined alternating sign matrix theorem|journal=Journal of Combinatorial Theory, Series A|year=2005|volume=114|issue=2|pages=253–264|doi=10.1016/j.jcta.2006.04.004|arxiv=math/0507270|bibcode=2005math......7270F}}</ref>

==Razumov–Stroganov problem==

In 2001, A. Razumov and Y. Stroganov conjectured a connection between O(1) loop model, fully packed loop model (FPL) and ASMs.<ref>Razumov, A.V., Stroganov Yu.G., [https://arxiv.org/abs/cond-mat/0012141 Spin chains and combinatorics], ''Journal of Physics A'', '''34''' (2001), [tel:[phone]-3190].</ref>

This conjecture was proved in 2010 by Cantini and Sportiello.<ref>L. Cantini and A. Sportiello, [https://arxiv.org/abs/1003.3376 Proof of the Razumov-Stroganov conjecture]''Journal of Combinatorial Theory, Series A'', '''118 (5)''', [tel:(2011)&#x20;1549–1574 (2011) 1549–1574],</ref>

==References==

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==Further reading==

* [[David Bressoud|Bressoud, David M.]], ''Proofs and Confirmations: The Story of the Alternating Sign Matrix Conjecture'', MAA Spectrum, Mathematical Associations of America, Washington, D.C., 1999.{{ISBN|978-0521666466}}

* [[David Bressoud|Bressoud, David M.]] and Propp, James, [https://www.ams.org/notices/199906/fea-bressoud.pdf How the alternating sign matrix conjecture was solved], ''Notices of the American Mathematical Society'', 46 (1999), 637–646.

* Mills, William H., [[David P. Robbins|Robbins, David P.]], and Rumsey, Howard Jr., Proof of the Macdonald conjecture, ''Inventiones Mathematicae'', 66 (1982), 73–87.

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{{Matrix classes}}

[[Category:Matrices (mathematics)]]

[[Category:Enumerative combinatorics]]