Tirthankar Bhattacharyya, Mainak Bhowmik, Haripada Sau
Consider a bounded symmetric domain $Omega$ with a finite pseudo-reflection group acting on it as a subgroup of the group of automorphisms. This gives rise to quotient domains by means of basic polynomials $theta$ which by virtue of being proper maps map the v Silov boundary of $Omega$ to the v Silov boundary of $theta(Omega)$. Thus, the natural measure on the v Silov boundary of $Omega$ can be pushed forward. This gives rise to Hardy spaces on the quotient domain. The study of Hankel operators on the Hardy spaces of the quotient domains is introduced. The use of the weak product space shows that an analogue of Hartman's theorem holds for the small Hankel operator. Nehari's theorem fails for the big Hankel operator and this has the consequence that when the domain $Omega$ is the polydisc $mathbb D^d$, the {em Hardy space} is not a projective object in the category of all Hilbert modules over the algebra $mathcal A (theta(mathbb D^d))$ of functions which are holomorphic in the quotient domain and continuous on the closure $overline {theta(mathbb D^d)}$. It is not a projective object in the category of cramped Hilbert modules either. Indeed, no projective object is known in these two categories. On the other hand, every normal Hilbert module over the algebra of continuous functions on the v Silov boundary, treated as a Hilbert module over the algebra $mathcal A (theta(mathbb D^d))$, is projective.
考虑一个有界对称域$Omega$,其上有一个有限伪反射群作为自变群的一个子群。这就通过基本多项式$theta$产生了商域,而基本多项式$theta$由于是适当的映射,可以把$Omega$的v Silov边界映射到$theta(Omega)$的v Silov边界。因此,$Omega$的v Silov边界上的自然度量可以向前推进。这就产生了商域上的哈代空间。介绍了商域哈代空间上汉克尔算子的研究。弱积空间的使用表明,哈曼定理的类似物对小汉克尔算子成立。对于大汉克尔算子,奈哈里定理失效了,其结果是,当域$Omega$是多圆盘$mathbb D^d$、在代数$mathcal A (theta(mathbb D^d))$上的所有希尔伯特模块的范畴中,{em Hardy space}并不是一个投影对象,而这些函数在引域中是全态的,并且在闭合$overline {theta(mathbbD^d)}$ 上是连续的。它也不是 cramped Hilbertmodules 范畴中的投影对象。事实上,在这两个范畴中没有已知的投影对象。另一方面,在 v Silov 边界上连续函数代数上的每一个正常希尔伯特模块,作为代数 $mathcal A (theta(mathbb D^d))$ 上的希尔伯特模块,都是投影的。
{"title":"Hankel operators and Projective Hilbert modules on quotients of bounded symmetric domains","authors":"Tirthankar Bhattacharyya, Mainak Bhowmik, Haripada Sau","doi":"arxiv-2409.04582","DOIUrl":"https://doi.org/arxiv-2409.04582","url":null,"abstract":"Consider a bounded symmetric domain $Omega$ with a finite pseudo-reflection\u0000group acting on it as a subgroup of the group of automorphisms. This gives rise\u0000to quotient domains by means of basic polynomials $theta$ which by virtue of\u0000being proper maps map the v Silov boundary of $Omega$ to the v Silov\u0000boundary of $theta(Omega)$. Thus, the natural measure on the v Silov\u0000boundary of $Omega$ can be pushed forward. This gives rise to Hardy spaces on\u0000the quotient domain. The study of Hankel operators on the Hardy spaces of the quotient domains is\u0000introduced. The use of the weak product space shows that an analogue of\u0000Hartman's theorem holds for the small Hankel operator. Nehari's theorem fails\u0000for the big Hankel operator and this has the consequence that when the domain\u0000$Omega$ is the polydisc $mathbb D^d$, the {em Hardy space} is not a\u0000projective object in the category of all Hilbert modules over the algebra\u0000$mathcal A (theta(mathbb D^d))$ of functions which are holomorphic in the\u0000quotient domain and continuous on the closure $overline {theta(mathbb\u0000D^d)}$. It is not a projective object in the category of cramped Hilbert\u0000modules either. Indeed, no projective object is known in these two categories.\u0000On the other hand, every normal Hilbert module over the algebra of continuous\u0000functions on the v Silov boundary, treated as a Hilbert module over the\u0000algebra $mathcal A (theta(mathbb D^d))$, is projective.","PeriodicalId":501036,"journal":{"name":"arXiv - MATH - Functional Analysis","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}