In this paper, we analyze the sum of squares hierarchy (SOS) on the ordering principle on n elements (which has N = Θ(n²) variables). We prove that degree O(√nlog(n)) SOS can prove the ordering principle. We then show that this upper bound is essentially tight by proving that for any ε > 0, SOS requires degree Ω(n^(1/2 - ε)) to prove the ordering principle.
@InProceedings{potechin:LIPIcs.CCC.2020.38, author = {Potechin, Aaron}, title = {{Sum of Squares Bounds for the Ordering Principle}}, booktitle = {35th Computational Complexity Conference (CCC 2020)}, pages = {38:1--38:37}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-156-6}, ISSN = {1868-8969}, year = {2020}, volume = {169}, editor = {Saraf, Shubhangi}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CCC.2020.38}, URN = {urn:nbn:de:0030-drops-125900}, doi = {10.4230/LIPIcs.CCC.2020.38}, annote = {Keywords: sum of squares hierarchy, proof complexity, ordering principle} }
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