{"title":"Approximation of eigenvalues for unbounded Jacobi matrices using finite submatrices","authors":"A. B. D. Monvel, Lech Zielinski","doi":"10.2478/s11533-013-0348-z","DOIUrl":"https://doi.org/10.2478/s11533-013-0348-z","url":null,"abstract":"We consider an infinite Jacobi matrix with off-diagonal entries dominated by the diagonal entries going to infinity. The corresponding self-adjoint operator J has discrete spectrum and our purpose is to present results on the approximation of eigenvalues of J by eigenvalues of its finite submatrices.","PeriodicalId":50988,"journal":{"name":"Central European Journal of Mathematics","volume":"94 1","pages":"445-463"},"PeriodicalIF":0.0,"publicationDate":"2014-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74242792","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}
{"title":"Some problems on narrow operators on function spaces","authors":"M. Popov, E. Semenov, D. O. Vatsek","doi":"10.2478/s11533-013-0358-x","DOIUrl":"https://doi.org/10.2478/s11533-013-0358-x","url":null,"abstract":"It is known that if a rearrangement invariant (r.i.) space E on [0, 1] has an unconditional basis then every linear bounded operator on E is a sum of two narrow operators. On the other hand, for the classical space E = L1[0, 1] having no unconditional basis the sum of two narrow operators is a narrow operator. We show that a Köthe space on [0, 1] having “lots” of nonnarrow operators that are sum of two narrow operators need not have an unconditional basis. However, we do not know if such an r.i. space exists. Another result establishes sufficient conditions on an r.i. space E under which the orthogonal projection onto the closed linear span of the Rademacher system is a hereditarily narrow operator. This, in particular, answers a question of the first named author and Randrianantoanina (Problem 11.9 in [Popov M., Randrianantoanina B., Narrow Operators on Function Spaces and Vector Lattices, de Gruyter Stud. Math., 45, Walter de Gruyter, Berlin, 2013]).","PeriodicalId":50988,"journal":{"name":"Central European Journal of Mathematics","volume":"70 1","pages":"476-482"},"PeriodicalIF":0.0,"publicationDate":"2014-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81554294","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}
{"title":"Relation modules of infinite groups, II","authors":"M. J. Evans","doi":"10.2478/s11533-013-0355-0","DOIUrl":"https://doi.org/10.2478/s11533-013-0355-0","url":null,"abstract":"Let Fn denote the free group of rank n and d(G) the minimal number of generators of the finitely generated group G. Suppose that R ↪ Fm ↠ G and S ↪ Fm ↠ G are presentations of G and let $$bar R$$ and $$bar S$$ denote the associated relation modules of G. It is well known that $$bar R oplus (mathbb{Z}G)^{d(G)} cong bar S oplus (mathbb{Z}G)^{d(G)}$$ even though it is quite possible that . However, to the best of the author’s knowledge no examples have appeared in the literature with the property that . Our purpose here is to exhibit, for each integer k ≥ 1, a group G that has presentations as above such that . Our approach depends on the existence of nonfree stably free modules over certain commutative rings and, in particular, on the existence of certain Hurwitz-Radon systems of matrices with integer entries discovered by Geramita and Pullman. This approach was motivated by results of Adams concerning the number of orthonormal (continuous) vector fields on spheres.","PeriodicalId":50988,"journal":{"name":"Central European Journal of Mathematics","volume":"51 1","pages":"436-444"},"PeriodicalIF":0.0,"publicationDate":"2014-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90296384","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}
{"title":"Inverse problems on star-type graphs: differential operators of different orders on different edges","authors":"V. Yurko","doi":"10.2478/s11533-013-0352-3","DOIUrl":"https://doi.org/10.2478/s11533-013-0352-3","url":null,"abstract":"We study inverse spectral problems for ordinary differential equations on compact star-type graphs when differential equations have different orders on different edges. As the main spectral characteristics we introduce and study the so-called Weyl-type matrices which are generalizations of the Weyl function (m-function) for the classical Sturm-Liouville operator. We provide a procedure for constructing the solution of the inverse problem and prove its uniqueness.","PeriodicalId":50988,"journal":{"name":"Central European Journal of Mathematics","volume":"26 1","pages":"483-499"},"PeriodicalIF":0.0,"publicationDate":"2014-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87487360","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}
{"title":"A non-homogeneous, symmetric contact projective structure","authors":"Lenka Zalabová","doi":"10.2478/s11533-013-0383-9","DOIUrl":"https://doi.org/10.2478/s11533-013-0383-9","url":null,"abstract":"We construct a non-homogeneous contact projective structure which is symmetric from the point of view of parabolic geometries.","PeriodicalId":50988,"journal":{"name":"Central European Journal of Mathematics","volume":"362 1","pages":"879-886"},"PeriodicalIF":0.0,"publicationDate":"2014-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75094077","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}
{"title":"Orbit algebras that are invariant under stable equivalences of Morita type","authors":"Z. Pogorzały","doi":"10.2478/s11533-013-0385-7","DOIUrl":"https://doi.org/10.2478/s11533-013-0385-7","url":null,"abstract":"In this note we show that there are a lot of orbit algebras that are invariant under stable equivalences of Morita type between self-injective algebras. There are also indicated some links between Auslander-Reiten periodicity of bimodules and noetherianity of their orbit algebras.","PeriodicalId":50988,"journal":{"name":"Central European Journal of Mathematics","volume":"217 1","pages":"813-823"},"PeriodicalIF":0.0,"publicationDate":"2014-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75778512","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}
{"title":"The cone of nonnegative polynomials with nonnegative coefficients and linear operators preserving this cone","authors":"O. Katkova, A. Vishnyakova","doi":"10.2478/s11533-013-0380-z","DOIUrl":"https://doi.org/10.2478/s11533-013-0380-z","url":null,"abstract":"Let be the cone of real univariate polynomials of degree ≤ 2n which are nonnegative on the real axis and have nonnegative coefficients. We describe the extremal rays of this convex cone and the class of linear operators, acting diagonally in the standard monomial basis, preserving this cone.","PeriodicalId":50988,"journal":{"name":"Central European Journal of Mathematics","volume":"11 1","pages":"752-760"},"PeriodicalIF":0.0,"publicationDate":"2014-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89533470","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}
{"title":"On the asymptotic form of convex hulls of Gaussian random fields","authors":"Y. Davydov, V. Paulauskas","doi":"10.2478/s11533-013-0375-9","DOIUrl":"https://doi.org/10.2478/s11533-013-0375-9","url":null,"abstract":"We consider a centered Gaussian random field X = {Xt : t ∈ T} with values in a Banach space $$mathbb{B}$$ defined on a parametric set T equal to ℝm or ℤm. It is supposed that the distribution of Xt is independent of t. We consider the asymptotic behavior of closed convex hulls Wn = conv{Xt : t ∈ Tn}, where (Tn) is an increasing sequence of subsets of T. We show that under some conditions of weak dependence for the random field under consideration and some sequence (bn)n≥1 with probability 1, (in the sense of Hausdorff distance), where the limit set is the concentration ellipsoid of . The asymptotic behavior of the mathematical expectations Ef(Wn), where f is some function, is also studied.","PeriodicalId":50988,"journal":{"name":"Central European Journal of Mathematics","volume":"20 1","pages":"711-720"},"PeriodicalIF":0.0,"publicationDate":"2014-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81165868","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}
{"title":"Boundary vs. interior conditions associated with weighted composition operators","authors":"K. Izuchi, Y. Izuchi, S. Ohno","doi":"10.2478/s11533-013-0377-7","DOIUrl":"https://doi.org/10.2478/s11533-013-0377-7","url":null,"abstract":"Associated with some properties of weighted composition operators on the spaces of bounded harmonic and analytic functions on the open unit disk $$mathbb{D}$$, we obtain conditions in terms of behavior of weight functions and analytic self-maps on the interior $$mathbb{D}$$ and on the boundary $$partial mathbb{D}$$ respectively. We give direct proofs of the equivalence of these interior and boundary conditions. Furthermore we give another proof of the estimate for the essential norm of the difference of weighted composition operators.","PeriodicalId":50988,"journal":{"name":"Central European Journal of Mathematics","volume":"46 1","pages":"761-777"},"PeriodicalIF":0.0,"publicationDate":"2014-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80463874","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}
{"title":"On the nonlocal Cauchy problem for semilinear fractional order evolution equations","authors":"Jinrong Wang, Yong Zhou, Michal Feckan","doi":"10.2478/s11533-013-0381-y","DOIUrl":"https://doi.org/10.2478/s11533-013-0381-y","url":null,"abstract":"In this paper, we develop the approach and techniques of [Boucherif A., Precup R., Semilinear evolution equations with nonlocal initial conditions, Dynam. Systems Appl., 2007, 16(3), 507–516], [Zhou Y., Jiao F., Nonlocal Cauchy problem for fractional evolution equations, Nonlinar Anal. Real World Appl., 2010, 11(5), 4465–4475] to deal with nonlocal Cauchy problem for semilinear fractional order evolution equations. We present two new sufficient conditions on existence of mild solutions. The first result relies on a growth condition on the whole time interval via Schaefer fixed point theorem. The second result relies on a growth condition splitted into two parts, one for the subinterval containing the points associated with the nonlocal conditions, and the other for the rest of the interval via O’Regan fixed point theorem.","PeriodicalId":50988,"journal":{"name":"Central European Journal of Mathematics","volume":"21 1","pages":"911-922"},"PeriodicalIF":0.0,"publicationDate":"2014-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82543820","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}