Pedro F. dos Santos , Carlos Florentino , Javier Orts
{"title":"用Bredon上同调刻画极大变异","authors":"Pedro F. dos Santos , Carlos Florentino , Javier Orts","doi":"10.1016/j.topol.2025.109544","DOIUrl":null,"url":null,"abstract":"<div><div>We obtain a characterization of Maximal and Galois-Maximal <span><math><msub><mrow><mi>C</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>-spaces (including real algebraic varieties) in terms of <span><math><mrow><mi>RO</mi></mrow><mo>(</mo><msub><mrow><mi>C</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>)</mo></math></span>-graded cohomology with coefficients in the constant Mackey functor <span><math><msub><mrow><munder><mrow><mi>F</mi></mrow><mo>_</mo></munder></mrow><mrow><mn>2</mn></mrow></msub></math></span>, using the structure theorem of Clover May. Other known characterizations, for instance in terms of equivariant Borel cohomology, are also rederived from this. For the particular case of a smooth projective real variety <em>V</em>, equivariant Poincaré duality is used to deduce further symmetry restrictions for the decomposition of the <span><math><mrow><mi>RO</mi></mrow><mo>(</mo><msub><mrow><mi>C</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>)</mo></math></span>-graded cohomology of the complex locus <span><math><mi>V</mi><mo>(</mo><mi>C</mi><mo>)</mo></math></span> given by the same structure theorem. We illustrate this result with some computations, including the <span><math><mrow><mi>RO</mi></mrow><mo>(</mo><msub><mrow><mi>C</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>)</mo></math></span>-graded cohomology with <span><math><msub><mrow><munder><mrow><mi>F</mi></mrow><mo>_</mo></munder></mrow><mrow><mn>2</mn></mrow></msub></math></span> coefficients of real <em>K</em>3 surfaces.</div></div>","PeriodicalId":51201,"journal":{"name":"Topology and its Applications","volume":"375 ","pages":"Article 109544"},"PeriodicalIF":0.5000,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Characterizing maximal varieties via Bredon cohomology\",\"authors\":\"Pedro F. dos Santos , Carlos Florentino , Javier Orts\",\"doi\":\"10.1016/j.topol.2025.109544\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>We obtain a characterization of Maximal and Galois-Maximal <span><math><msub><mrow><mi>C</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>-spaces (including real algebraic varieties) in terms of <span><math><mrow><mi>RO</mi></mrow><mo>(</mo><msub><mrow><mi>C</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>)</mo></math></span>-graded cohomology with coefficients in the constant Mackey functor <span><math><msub><mrow><munder><mrow><mi>F</mi></mrow><mo>_</mo></munder></mrow><mrow><mn>2</mn></mrow></msub></math></span>, using the structure theorem of Clover May. Other known characterizations, for instance in terms of equivariant Borel cohomology, are also rederived from this. For the particular case of a smooth projective real variety <em>V</em>, equivariant Poincaré duality is used to deduce further symmetry restrictions for the decomposition of the <span><math><mrow><mi>RO</mi></mrow><mo>(</mo><msub><mrow><mi>C</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>)</mo></math></span>-graded cohomology of the complex locus <span><math><mi>V</mi><mo>(</mo><mi>C</mi><mo>)</mo></math></span> given by the same structure theorem. We illustrate this result with some computations, including the <span><math><mrow><mi>RO</mi></mrow><mo>(</mo><msub><mrow><mi>C</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>)</mo></math></span>-graded cohomology with <span><math><msub><mrow><munder><mrow><mi>F</mi></mrow><mo>_</mo></munder></mrow><mrow><mn>2</mn></mrow></msub></math></span> coefficients of real <em>K</em>3 surfaces.</div></div>\",\"PeriodicalId\":51201,\"journal\":{\"name\":\"Topology and its Applications\",\"volume\":\"375 \",\"pages\":\"Article 109544\"},\"PeriodicalIF\":0.5000,\"publicationDate\":\"2025-08-14\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Topology and its Applications\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0166864125003426\",\"RegionNum\":4,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Topology and its Applications","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0166864125003426","RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS","Score":null,"Total":0}
Characterizing maximal varieties via Bredon cohomology
We obtain a characterization of Maximal and Galois-Maximal -spaces (including real algebraic varieties) in terms of -graded cohomology with coefficients in the constant Mackey functor , using the structure theorem of Clover May. Other known characterizations, for instance in terms of equivariant Borel cohomology, are also rederived from this. For the particular case of a smooth projective real variety V, equivariant Poincaré duality is used to deduce further symmetry restrictions for the decomposition of the -graded cohomology of the complex locus given by the same structure theorem. We illustrate this result with some computations, including the -graded cohomology with coefficients of real K3 surfaces.
期刊介绍:
Topology and its Applications is primarily concerned with publishing original research papers of moderate length. However, a limited number of carefully selected survey or expository papers are also included. The mathematical focus of the journal is that suggested by the title: Research in Topology. It is felt that it is inadvisable to attempt a definitive description of topology as understood for this journal. Certainly the subject includes the algebraic, general, geometric, and set-theoretic facets of topology as well as areas of interactions between topology and other mathematical disciplines, e.g. topological algebra, topological dynamics, functional analysis, category theory. Since the roles of various aspects of topology continue to change, the non-specific delineation of topics serves to reflect the current state of research in topology.
At regular intervals, the journal publishes a section entitled Open Problems in Topology, edited by J. van Mill and G.M. Reed. This is a status report on the 1100 problems listed in the book of the same name published by North-Holland in 1990, edited by van Mill and Reed.