{"title":"Amitsur-Small环","authors":"Adam Chapman , Elad Paran","doi":"10.1016/j.jalgebra.2025.04.049","DOIUrl":null,"url":null,"abstract":"<div><div>Let <span><math><msub><mrow><mi>R</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>=</mo><mi>D</mi><mo>[</mo><msub><mrow><mi>x</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>x</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>]</mo></math></span> denote the ring of polynomials in <em>n</em> central variables over a division ring <em>D</em>. We say that <em>D</em> is an <em>Amitsur-Small ring</em> if for any maximal left ideal in <span><math><msub><mrow><mi>R</mi></mrow><mrow><mi>n</mi></mrow></msub></math></span>, <span><math><mi>M</mi><mo>∩</mo><msub><mrow><mi>R</mi></mrow><mrow><mi>k</mi></mrow></msub></math></span> is a maximal left ideal in <span><math><msub><mrow><mi>R</mi></mrow><mrow><mi>k</mi></mrow></msub></math></span>, for all <span><math><mi>n</mi><mo>∈</mo><mi>N</mi></math></span> and <span><math><mn>1</mn><mo>≤</mo><mi>k</mi><mo>≤</mo><mi>n</mi></math></span>. We demonstrate the existence of non Amitsur-Small division rings, providing a negative answer to a question of Amitsur and Small from 1978. We show that Hamilton's real quaternion algebra <span><math><mi>H</mi><mo>=</mo><msub><mrow><mo>(</mo><mo>−</mo><mn>1</mn><mo>,</mo><mo>−</mo><mn>1</mn><mo>)</mo></mrow><mrow><mn>2</mn><mo>,</mo><mi>R</mi></mrow></msub></math></span> is an Amitsur-Small ring, division rings of degree 3 over their center <em>F</em> are never Amitsur-Small, and division rings of degree 2 are not Amitsur-Small if they are not quaternion algebras <span><math><msub><mrow><mo>(</mo><mo>−</mo><mn>1</mn><mo>,</mo><mo>−</mo><mn>1</mn><mo>)</mo></mrow><mrow><mn>2</mn><mo>,</mo><mi>F</mi></mrow></msub></math></span> over a Pythagorean field <em>F</em>.</div></div>","PeriodicalId":14888,"journal":{"name":"Journal of Algebra","volume":"679 ","pages":"Pages 86-95"},"PeriodicalIF":0.8000,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Amitsur-Small rings\",\"authors\":\"Adam Chapman , Elad Paran\",\"doi\":\"10.1016/j.jalgebra.2025.04.049\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Let <span><math><msub><mrow><mi>R</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>=</mo><mi>D</mi><mo>[</mo><msub><mrow><mi>x</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>x</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>]</mo></math></span> denote the ring of polynomials in <em>n</em> central variables over a division ring <em>D</em>. We say that <em>D</em> is an <em>Amitsur-Small ring</em> if for any maximal left ideal in <span><math><msub><mrow><mi>R</mi></mrow><mrow><mi>n</mi></mrow></msub></math></span>, <span><math><mi>M</mi><mo>∩</mo><msub><mrow><mi>R</mi></mrow><mrow><mi>k</mi></mrow></msub></math></span> is a maximal left ideal in <span><math><msub><mrow><mi>R</mi></mrow><mrow><mi>k</mi></mrow></msub></math></span>, for all <span><math><mi>n</mi><mo>∈</mo><mi>N</mi></math></span> and <span><math><mn>1</mn><mo>≤</mo><mi>k</mi><mo>≤</mo><mi>n</mi></math></span>. We demonstrate the existence of non Amitsur-Small division rings, providing a negative answer to a question of Amitsur and Small from 1978. We show that Hamilton's real quaternion algebra <span><math><mi>H</mi><mo>=</mo><msub><mrow><mo>(</mo><mo>−</mo><mn>1</mn><mo>,</mo><mo>−</mo><mn>1</mn><mo>)</mo></mrow><mrow><mn>2</mn><mo>,</mo><mi>R</mi></mrow></msub></math></span> is an Amitsur-Small ring, division rings of degree 3 over their center <em>F</em> are never Amitsur-Small, and division rings of degree 2 are not Amitsur-Small if they are not quaternion algebras <span><math><msub><mrow><mo>(</mo><mo>−</mo><mn>1</mn><mo>,</mo><mo>−</mo><mn>1</mn><mo>)</mo></mrow><mrow><mn>2</mn><mo>,</mo><mi>F</mi></mrow></msub></math></span> over a Pythagorean field <em>F</em>.</div></div>\",\"PeriodicalId\":14888,\"journal\":{\"name\":\"Journal of Algebra\",\"volume\":\"679 \",\"pages\":\"Pages 86-95\"},\"PeriodicalIF\":0.8000,\"publicationDate\":\"2025-05-23\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Algebra\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0021869325002844\",\"RegionNum\":2,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Algebra","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0021869325002844","RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
Let denote the ring of polynomials in n central variables over a division ring D. We say that D is an Amitsur-Small ring if for any maximal left ideal in , is a maximal left ideal in , for all and . We demonstrate the existence of non Amitsur-Small division rings, providing a negative answer to a question of Amitsur and Small from 1978. We show that Hamilton's real quaternion algebra is an Amitsur-Small ring, division rings of degree 3 over their center F are never Amitsur-Small, and division rings of degree 2 are not Amitsur-Small if they are not quaternion algebras over a Pythagorean field F.
期刊介绍:
The Journal of Algebra is a leading international journal and publishes papers that demonstrate high quality research results in algebra and related computational aspects. Only the very best and most interesting papers are to be considered for publication in the journal. With this in mind, it is important that the contribution offer a substantial result that will have a lasting effect upon the field. The journal also seeks work that presents innovative techniques that offer promising results for future research.