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Kato–Ponce inequality with $$A_{\vec P}$$ weights Collect. Math. (IF 1.1) Pub Date : 2024-03-25 Sean Douglas
We prove the Kato–Ponce inequality (fractional normed Leibniz rule) for multiple factors in the setting of multiple weights (\(A_{\vec P}\) weights). This improves existing results to the product of m factors and extends the class of known weights for which the inequality holds.
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Maximal function characterization of Hardy spaces related to Laguerre polynomial expansions Collect. Math. (IF 1.1) Pub Date : 2024-03-19 Jorge J. Betancor, Estefanía Dalmasso, Pablo Quijano, Roberto Scotto
In this paper we introduce the atomic Hardy space \(\mathcal {H}^1((0,\infty ),\gamma _\alpha )\) associated with the non-doubling probability measure \(d\gamma _\alpha (x)=\frac{2x^{2\alpha +1}}{\Gamma (\alpha +1)}e^{-x^2}dx\) on \((0,\infty )\), for \({\alpha >-\frac{1}{2}}\). We obtain characterizations of \(\mathcal {H}^1((0,\infty ),\gamma _\alpha )\) by using two local maximal functions. We also
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Commuting Toeplitz and small Hankel operators on the Bergman space Collect. Math. (IF 1.1) Pub Date : 2024-03-14 Jiawei Wang, Jie Zhang, Xianfeng Zhao
This paper shows that on the Bergman space of the open unit disk, the Toeplitz operator \(T_{{\overline{p}}+\varphi }\) and the small Hankel operator \(\Gamma _\psi\) commute only in the obvious cases, where \(\varphi\) and \(\psi\) are both bounded analytic functions, and p is an analytic polynomial.
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Connecting ideals in evolution algebras with hereditary subsets of its associated graph Collect. Math. (IF 1.1) Pub Date : 2024-03-14 Yolanda Cabrera Casado, Dolores Martín Barquero, Cándido Martín González, Alicia Tocino
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Generalized Cesàro operators in weighted Banach spaces of analytic functions with sup-norms Collect. Math. (IF 1.1) Pub Date : 2024-03-12
Abstract An investigation is made of the generalized Cesàro operators \(C_t\) , for \(t\in [0,1]\) , when they act on the space \(H({{\mathbb {D}}})\) of holomorphic functions on the open unit disc \({{\mathbb {D}}}\) , on the Banach space \(H^\infty \) of bounded analytic functions and on the weighted Banach spaces \(H_v^\infty \) and \(H_v^0\) with their sup-norms. Of particular interest are the
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On reduction numbers and Castelnuovo–Mumford regularity of blowup rings and modules Collect. Math. (IF 1.1) Pub Date : 2024-03-07 Cleto B. Miranda-Neto, Douglas S. Queiroz
We prove new results on the interplay between reduction numbers and the Castelnuovo–Mumford regularity of blowup algebras and blowup modules, the key basic tool being the operation of Ratliff–Rush closure. First, we answer in two particular cases a question of M. E. Rossi, D. T. Trung, and N. V. Trung about Rees algebras of ideals in two-dimensional Buchsbaum local rings, and we even ask whether one
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New insights on slant submanifolds in almost Hermitian geometry Collect. Math. (IF 1.1) Pub Date : 2024-02-13 Adara M. Blaga
We provide the necessary and sufficient condition for a pointwise slant submanifold with respect to two anti-commuting almost Hermitian structures to be also pointwise slant with respect to a family of almost Hermitian structures generated by them. On the other hand, we show that the property of being pointwise slant is transitive on a class of proper pointwise slant immersed submanifolds of almost
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Identifiability and singular locus of secant varieties to Grassmannians Collect. Math. (IF 1.1) Pub Date : 2024-01-06 Vincenzo Galgano, Reynaldo Staffolani
Secant varieties are among the main protagonists in tensor decomposition, whose study involves both pure and applied mathematic areas. Grassmannians are the building blocks for skewsymmetric tensors. Although they are ubiquitous in the literature, the geometry of their secant varieties is not completely understood. In this work we determine the singular locus of the secant variety of lines to a Grassmannian
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On the depth of simplicial affine semigroup rings Collect. Math. (IF 1.1) Pub Date : 2024-01-02 Raheleh Jafari, Ignacio Ojeda
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Lorentzian connections with parallel twistor-free torsion Collect. Math. (IF 1.1) Pub Date : 2023-12-30 Igor Ernst, Anton S. Galaev
We describe Lorentzian manifolds that admit metric connections with parallel torsion having zero twistorial component and non-zero vectorial component. We also describe Lorentzian manifolds admitting metric connections with closed parallel skew-symmetric torsion.
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Stability of standard Einstein metrics on homogeneous spaces of non-simple Lie groups Collect. Math. (IF 1.1) Pub Date : 2023-12-28 Valeria Gutiérrez, Jorge Lauret
The classification of compact homogeneous spaces of the form \(M=G/K\), where G is a non-simple Lie group, such that the standard metric is Einstein is still open. The only known examples are 4 infinite families and 3 isolated spaces found by Nikonorov and Rodionov in the 90 s. In this paper, we prove that most of these standard Einstein metrics are unstable as critical points of the scalar curvature
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A Grayson-type theorem for star-shaped curves Collect. Math. (IF 1.1) Pub Date : 2023-12-11 Jianbo Fang, Yunlong Yang, Fangwei Chen
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Cox rings of blow-ups of multiprojective spaces Collect. Math. (IF 1.1) Pub Date : 2023-12-07 Michele Bolognesi, Alex Massarenti, Elena Poma
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Fujita exponent on stratified Lie groups Collect. Math. (IF 1.1) Pub Date : 2023-12-01 Durvudkhan Suragan, Bharat Talwar
We prove that \(\frac{Q}{Q-2}\) is the Fujita exponent for a semilinear heat equation on an arbitrary stratified Lie group with homogeneous dimension Q. This covers the Euclidean case and gives new insight into proof techniques on nilpotent Lie groups. The equation we study has a forcing term which depends only upon the group elements and has positive integral. The stratified Lie group structure plays
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Infinitely many positive energy solutions for semilinear Neumann equations with critical Sobolev exponent and concave-convex nonlinearity Collect. Math. (IF 1.1) Pub Date : 2023-11-29 Rachid Echarghaoui, Rachid Sersif, Zakaria Zaimi
The authors of Cao and Yan (J Differ Equ 251:1389–1414, 2011) have considered the following semilinear critical Neumann problem $$\begin{aligned} \varvec{-\Delta u=\vert u\vert ^{2^{*}-2} u+g(u) \quad \text{ in } \Omega , \quad \frac{\partial u}{\partial \nu }=0 \quad \text{ on } \partial \Omega ,} \end{aligned}$$ where \(\varvec{\Omega }\) is a bounded domain in \(\varvec{\mathbb {R}^{N}}\) satisfying
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Maximal operators on hyperbolic triangles Collect. Math. (IF 1.1) Pub Date : 2023-11-25 Romain Branchereau, Samuel Bronstein, Anthony Gauvan
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Cofiniteness of local cohomology modules and subcategories of modules Collect. Math. (IF 1.1) Pub Date : 2023-11-21 Ryo Takahashi, Naoki Wakasugi
Let R be a commutative noetherian ring and I an ideal of R. Assume that for all integers i the local cohomology module \({\text {H}}_I^i(R)\) is I-cofinite. Suppose that \(R_\mathfrak {p}\) is a regular local ring for all prime ideals \(\mathfrak {p}\) that do not contain I. In this paper, we prove that if the I-cofinite modules form an abelian category, then for all finitely generated R-modules M
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On the interior Bernoulli free boundary problem for the fractional Laplacian on an interval Collect. Math. (IF 1.1) Pub Date : 2023-11-08 Tadeusz Kulczycki, Jacek Wszoła
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Skew derivations of incidence algebras Collect. Math. (IF 1.1) Pub Date : 2023-11-04 Érica Z. Fornaroli, Mykola Khrypchenko
In the first part of the paper we describe \(\varphi\)-derivations of the incidence algebra I(X, K) of a locally finite poset X over a field K, where \(\varphi\) is an arbitrary automorphism of I(X, K). We show that they admit decompositions similar to that of usual derivations of I(X, K). In particular, the quotient of the space of \(\varphi\)-derivations of I(X, K) by the subspace of inner \(\varphi\)-derivations
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Refined two weight estimates for the Bergman projection Collect. Math. (IF 1.1) Pub Date : 2023-11-01 Gianmarco Brocchi
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On the Lipschitz numerical index of Banach spaces Collect. Math. (IF 1.1) Pub Date : 2023-10-27 Geunsu Choi, Mingu Jung, Hyung-Joon Tag
In this article, we investigate further on the Lipschitz numerical radius and index which were recently introduced. First, we provide some renorming results on Lipschitz numerical index and introduce a concept of Lipschitz numerical radius attaining maps. Namely, we observe that for any Banach space X, the set of Lipschitz numerical indices of Banach spaces which are isomorphic to X is an interval
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Attractor for minimal iterated function systems Collect. Math. (IF 1.1) Pub Date : 2023-10-24 Aliasghar Sarizadeh
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Disjoint hypercyclic and supercyclic composition operators on discrete weighted Banach spaces Collect. Math. (IF 1.1) Pub Date : 2023-10-21 Zhiyuan Xu, Ya Wang, Zehua Zhou
In this paper, we characterize the disjoint hypercyclic and disjoint supercyclic composition operators on the little weighted Banach space \(L^0_\mu (T)\) defined on an unbounded, locally finite metric space T with a distinguished element. We give an explanation of the conditions which are needed and list some examples simultaneously.
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Morelli-Włodarczyk cobordism and examples of rooftop flips Collect. Math. (IF 1.1) Pub Date : 2023-09-19 Lorenzo Barban, Alberto Franceschini
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On the Hilbert function of a finite scheme contained in a quadric surface Collect. Math. (IF 1.1) Pub Date : 2023-09-04 Mario Maican
Consider a finite scheme of length l contained in a smooth quadric surface over the complex numbers. We determine the number of linearly independent curves passing through the scheme, of degree at least \(l - 2\).
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Connected domination in graphs and v-numbers of binomial edge ideals Collect. Math. (IF 1.1) Pub Date : 2023-08-26 Delio Jaramillo-Velez, Lisa Seccia
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The adjoint of an operator on a Banach space Collect. Math. (IF 1.1) Pub Date : 2023-08-21 Francisco Javier García-Pacheco
Self-adjoint operators in smooth Banach spaces have been already defined in recent works. Here, we extend the concept of adjoint of an operator to the scope of (non-necessarily Hilbert) Banach spaces, obtaining in particular the notion of self-adjoint operator in the non-smooth case. As a consequence, we define the probability density operator on Banach spaces and verify most of its well-known properties
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Elliptic curves, ACM bundles and Ulrich bundles on prime Fano threefolds Collect. Math. (IF 1.1) Pub Date : 2023-08-21 Ciro Ciliberto, Flaminio Flamini, Andreas Leopold Knutsen
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A weak version of the Mond conjecture Collect. Math. (IF 1.1) Pub Date : 2023-08-08 R. Giménez Conejero, J. J. Nuño-Ballesteros
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The b-Gelfand–Phillips property for locally convex spaces Collect. Math. (IF 1.1) Pub Date : 2023-08-06 T. Banakh, S. Gabriyelyan
We extend the well-known Gelfand–Phillips property for Banach spaces to locally convex spaces, defining a locally convex space E to be b-Gelfand–Phillips if every limited set in E, which is bounded in the strong topology \(\beta (E,E')\) on E, is precompact in \(\beta (E,E').\) Several characterizations of b-Gelfand–Phillips spaces are given. The problem of preservation of the b-Gelfand–Phillips property
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The edge ideals of $${{\textbf{t}}}$$ -spread d-partite hypergraphs Collect. Math. (IF 1.1) Pub Date : 2023-08-01 Asli Musapaşaoğlu, Mehrdad Nasernejad, Ayesha Asloob Qureshi
Inspired by the definition of \({{\textbf{t}}}\)-spread monomial ideals, in this paper, we introduce \({{\textbf{t}}}\)-spread d-partite hypergraph \({\text {K}}^{{{\textbf{t}}}}_{{\text {V}}}\) and study its edge ideal \(I({\text {K}}^{{{\textbf{t}}}}_{{\text {V}}})\). We prove that \(I({\text {K}}^{{{\textbf{t}}}}_{{\text {V}}})\) has linear quotients, all powers of \(I({\text {K}}^{{{\textbf{t}}}}_{{\text
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Vertex decomposability, shellability and Cohen–Macaulayness of graphs upon graph operations Collect. Math. (IF 1.1) Pub Date : 2023-06-22 Fahimeh Khosh-Ahang Ghasr
Throughout this work, the vertex decomposability and shellability of graphs formed from other graphs by various operations are investigated. Also among the other things, by using some graph operations, new classes of Cohen–Macaulay graphs from previous ones are presented.
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Intersection graph of idealizations Collect. Math. (IF 1.1) Pub Date : 2023-06-13 Akram Mahmoodi, Alireza Vahidi, Raufeh Manaviyat, Roghaieh Alipour
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Continuity of the Perron–Bremermann envelope of plurisubharmonic functions Collect. Math. (IF 1.1) Pub Date : 2023-06-11 Tang Van Long, Nguyen Xuan Hong, Pham Thi Lieu
In this paper we are interested in studying the Perron–Bremermann envelope of plurisubharmonic functions. We give a sufficient condition for the envelope to be Hölder continuous.
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Indecomposability of derived categories for arbitrary schemes Collect. Math. (IF 1.1) Pub Date : 2023-05-18 Ana Cristina López Martín, Fernando Sancho de Salas
We extend the criterion of Kawatani and Okawa for indecomposability of the derived category of a smooth projective variety to arbitrary schemes. For relative schemes, we also give a criterion for the nonexistence of semiorthogonal decompositions that are linear over the base. These criteria are based on the base loci of the global or relative dualizing complexes.
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The enumerative geometry of cubic hypersurfaces: point and line conditions Collect. Math. (IF 1.1) Pub Date : 2023-05-03 Mara Belotti, Alessandro Danelon, Claudia Fevola, Andreas Kretschmer
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Nash blowups of toric varieties in prime characteristic Collect. Math. (IF 1.1) Pub Date : 2023-04-28 Daniel Duarte, Jack Jeffries, Luis Núñez-Betancourt
We initiate the study of the resolution of singularities properties of Nash blowups over fields of prime characteristic. We prove that the iteration of normalized Nash blowups desingularizes normal toric surfaces. We also introduce a prime characteristic version of the logarithmic Jacobian ideal of a toric variety and prove that its blowup coincides with the Nash blowup of the variety. As a consequence
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Bilinear pseudodifferential operators with symbol in $$BS_{1,1}^m$$ on Triebel–Lizorkin spaces with critical Sobolev index Collect. Math. (IF 1.1) Pub Date : 2023-03-19 Sergi Arias, Salvador Rodríguez-López
In this paper we obtain new estimates for bilinear pseudodifferential operators with symbol in the class \(BS_{1,1}^m\), when both arguments belong to Triebel-Lizorkin spaces of the type \(F_{p,q}^{n/p}({\mathbb {R}}^n)\). The inequalities are obtained as a consequence of a refinement of the classical Sobolev embedding \(F^{n/p}_{p,q}({\mathbb {R}}^n)\hookrightarrow \textrm{bmo}({\mathbb {R}}^n)\)
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Restricted secant varieties of Grassmannians Collect. Math. (IF 1.1) Pub Date : 2023-03-10 Dalton Bidleman, Luke Oeding
Restricted secant varieties of Grassmannians are constructed from sums of points corresponding to k-planes with the restriction that their intersection has a prescribed dimension. We study dimensions of restricted secant of Grassmannians and relate them to the analogous question for secants of Grassmannians via an incidence variety construction. We define a notion of expected dimension and give a formula
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Lower bounds for the depth of the second power of edge ideals Collect. Math. (IF 1.1) Pub Date : 2023-03-07 S. A. Seyed Fakhari
Assume that G is a graph with edge ideal I(G). We provide sharp lower bounds for the depth of \(I(G)^2\) in terms of the star packing number of G.
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Massey products and Fujita decomposition over higher dimensional base Collect. Math. (IF 1.1) Pub Date : 2023-02-25 Luca Rizzi
Let \(f:X\rightarrow Y\) be a semistable fibration between smooth complex varieties of dimension n and m. This paper contains an analysis of the local systems of de Rham closed relative one forms and top forms on the fibers. In particular the latter recovers the local system of the second Fujita decomposition of \(f_*\omega _{X/Y}\) over higher dimensional base. The so called theory of Massey products
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Positive Ricci curvature through Cheeger deformations Collect. Math. (IF 1.1) Pub Date : 2023-02-16 Leonardo F. Cavenaghi, Renato J. M. e Silva, Llohann D. Sperança
This paper is devoted to a deep analysis of the process known as Cheeger deformation, applied to manifolds with isometric group actions. Here, we provide new curvature estimates near singular orbits and present several applications. As the main result, we answer a question raised by a seminal result of Searle–Wilhelm about lifting positive Ricci curvature from the quotient of an isometric action. To
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Examples of twice differentiable functions with continuous Laplacian and unbounded Hessian Collect. Math. (IF 1.1) Pub Date : 2023-02-12 Yifei Pan, Yu Yan
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Stable trace ideals and applications Collect. Math. (IF 1.1) Pub Date : 2023-02-08 Hailong Dao, Haydee Lindo
We study stable trace ideals in one dimensional local Cohen–Macaulay rings and give numerous applications.
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Halfspace type theorems for self-shrinkers in arbitrary codimension Collect. Math. (IF 1.1) Pub Date : 2023-01-30 Hieu T. Doan, Duyen T. M. Nguyen
In this paper, we generalize some halfspace type theorems for self-shrinkers of codimension 1 to the case of arbitrary codimension.
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Banach spaces which always produce octahedral spaces of operators Collect. Math. (IF 1.1) Pub Date : 2023-01-27 Abraham Rueda Zoca
We characterise those Banach spaces X which satisfy that L(Y, X) is octahedral for every non-zero Banach space Y. They are those satisfying that, for every finite dimensional subspace Z, \(\ell _\infty \) can be finitely-representable in a part of X kind of \(\ell _1\)-orthogonal to Z. We also prove that L(Y, X) is octahedral for every Y if, and only if, \(L(\ell _p^n,X)\) is octahedral for every \(n\in
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The normalized depth function of squarefree powers Collect. Math. (IF 1.1) Pub Date : 2023-01-26 Nursel Erey, Jürgen Herzog, Takayuki Hibi, Sara Saeedi Madani
The depth of squarefree powers of a squarefree monomial ideal is introduced. Let I be a squarefree monomial ideal of the polynomial ring \(S=K[x_1,\ldots ,x_n]\). The k-th squarefree power \(I^{[k]}\) of I is the ideal of S generated by those squarefree monomials \(u_1\cdots u_k\) with each \(u_i\in G(I)\), where G(I) is the unique minimal system of monomial generators of I. Let \(d_k\) denote the
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Weighted estimates for the multilinear maximal operator Collect. Math. (IF 1.1) Pub Date : 2023-01-07 Adam Osękowski
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Extensions of modulation-dilation Bessel Systems in $$L^2({\mathbb R}_+)$$ Collect. Math. (IF 1.1) Pub Date : 2022-12-29 Ya-Nan Li, Yun-Zhang Li
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Hardy spaces associated to self-adjoint operators on general domains Collect. Math. (IF 1.1) Pub Date : 2022-12-22 Xuan Thinh Duong, Ming-Yi Lee, Ji Li, Chin-Cheng Lin
Let \((X,d,\mu )\) be the space of homogeneous type and \(\Omega \) be a measurable subset of X which may not satisfy the doubling condition. Let L denote a nonnegative self-adjoint operator on \(L^2(\Omega )\) which has a Gaussian upper bound on its heat kernel. The aim of this paper is to introduce a Hardy space \(H^1_L(\Omega )\) associated to L on \(\Omega \) which provides an appropriate setting
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Homotopy theory of monoid actions via group actions and an Elmendorf style theorem Collect. Math. (IF 1.1) Pub Date : 2022-12-21 Mehmet Akif Erdal
Let M be a monoid and \(G:\mathbf {Mon} \rightarrow \mathbf {Grp}\) be the group completion functor from monoids to groups. Given a collection \(\mathcal {X}\) of submonoids of M and for each \(N\in \mathcal {X}\) a collection \(\mathcal {Y}_N\) of subgroups of G(N), we construct a model structure on the category of M-spaces and M-equivariant maps, called the \((\mathcal {X},\mathcal {Y})\)-model structure
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Multi-Rees algebras of strongly stable ideals Collect. Math. (IF 1.1) Pub Date : 2022-11-22 Selvi Kara, Kuei-Nuan Lin, Gabriel Sosa Castillo
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Disjoint strong transitivity of composition operators Collect. Math. (IF 1.1) Pub Date : 2022-11-23 Noureddine Karim, Otmane Benchiheb, Mohamed Amouch
A Furstenberg family \(\mathcal {F}\) is a collection of infinite subsets of the set of positive integers such that if \(A\subset B\) and \(A\in \mathcal {F}\), then \(B\in \mathcal {F}\). For a Furstenberg family \(\mathcal {F}\), finitely many operators \(T_1,...,T_N\) acting on a common topological vector space X are said to be disjoint \(\mathcal {F}\)-transitive if for every non-empty open subsets
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Lefschetz properties for jacobian rings of cubic fourfolds and other Artinian algebras Collect. Math. (IF 1.1) Pub Date : 2022-11-19 Davide Bricalli, Filippo Francesco Favale
In this paper, we exploit some geometric-differential techniques to prove the strong Lefschetz property in degree 1 for a complete intersection standard Artinian Gorenstein algebra of codimension 6 presented by quadrics. We prove also some strong Lefschetz properties for the same kind of Artinian algebras in higher codimensions. Moreover, we analyze some loci that come naturally into the picture of
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The moduli space of quasistable spin curves Collect. Math. (IF 1.1) Pub Date : 2022-11-18 Alex Abreu, Marco Pacini, Danny Taboada
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Spacelike mean curvature flow solitons, polynomial volume growth and stochastic completeness of spacelike hypersurfaces immersed into pp-vave spacetimes Collect. Math. (IF 1.1) Pub Date : 2022-11-15 Marco A. L. Velásquez, Henrique F. de Lima, José H. H. de Lacerda
Our purpose in this paper is to study some geometric properties of spacelike hypersurfaces immersed into a pp-wave spacetime, namely, a connected Lorentzian manifold admitting a parallel lightlike vector field. Initially, by applying a new form of maximum principle for smooth functions on a complete noncompact Riemannian manifold, we obtain sufficient conditions which guarantee that a complete noncompact
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On weighted compactness of commutators of square function and semi-group maximal function associated to Schrödinger operators Collect. Math. (IF 1.1) Pub Date : 2022-11-01 Shifen Wang, Qingying Xue, Chunmei Zhang
Let \(\Delta\) be the Laplacian operator on \({\mathbb{R}}^n\) and V be a nonnegative potential satisfying an appropriate reverse Hölder inequality. The Littlewood–Paley square function g associated with the Schrödinger operator \(L=-\Delta +V\) is defined by: $$\begin{aligned} g(f)(x)=\Big (\int _{0}^{\infty }\Big |\frac{d}{dt}e^{-tL}(f)(x)\Big |^2tdt\Big )^{1/2}. \end{aligned}$$ In this paper, we
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The symmetrization map and $$\Gamma$$ -contractions Collect. Math. (IF 1.1) Pub Date : 2022-10-25 Sourav Pal
The symmetrization map \(\pi :{\mathbb{C}}^2\rightarrow {\mathbb{C}}^2\) is defined by \(\pi (z_1,z_2)=(z_1+z_2,z_1z_2).\) The closed symmetrized bidisc \(\Gamma\) is the symmetrization of the closed unit bidisc \(\overline{{\mathbb{D}}^2}\), that is, $$\begin{aligned} \Gamma = \pi (\overline{{\mathbb{D}}^2})=\{ (z_1+z_2,z_1z_2)\,:\, |z_i|\le 1, i=1,2 \}. \end{aligned}$$ A pair of commuting Hilbert
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Morse index bounds for minimal submanifolds Collect. Math. (IF 1.1) Pub Date : 2022-10-21 Diego Adauto, Márcio Batista
In this paper, we study the Morse index of closed minimal submanifolds immersed into general Riemannian manifolds. Using the strategy developed by Ambrozio et al. (J Differ Geom 108(3):379–410, 2018) and under a suitable constrain on the submanifold, we obtain that the Morse index of the submanifold is bounded from below by a linear function of its first Betti’s number, as conjectured by Schoen and