当前期刊: Geometriae Dedicata Go to current issue    加入关注   
显示样式:        排序: IF: - GO 导出
我的关注
我的收藏
您暂时未登录!
登录
  • Tilings from graph directed iterated function systems
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-08-09
    Michael Barnsley, Andrew Vince

    A new method for constructing self-referential tilings of Euclidean space from a graph directed iterated function system (GIFS), based on a combinatorial structure we call a pre-tree, is introduced. For each GIFS, a family of tilings is constructed indexed by a parameter. For what we call a commensurate GIFS, our method is used to define what we refer to as balanced tilings. Under mild conditions on

    更新日期:2020-08-09
  • Convex plumbings in closed hyperbolic 4-manifolds
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-08-07
    Bruno Martelli, Stefano Riolo, Leone Slavich

    We show that every plumbing of disc bundles over surfaces whose genera satisfy a simple inequality may be embedded as a convex submanifold in some closed hyperbolic four-manifold. In particular its interior has a geometrically finite hyperbolic structure that covers a closed hyperbolic four-manifold.

    更新日期:2020-08-08
  • Three new almost positively curved manifolds
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-08-07
    Jason DeVito

    A Riemannian manifold is called almost positively curved if the set of points for which all 2-planes have positive sectional curvature is open and dense. We find three new examples of almost positively curved manifolds: \(Sp(3)/Sp(1)^2\), and two circle quotients of \(Sp(3)/Sp(1)^2\). We also show the quasi-positively curved metric of Tapp (J Differ Geom 65:273–287, 2003) on \(Sp(n+1)/Sp(n-1) Sp(1)\)

    更新日期:2020-08-08
  • Linear-central filtrations and the image of the Burau representation
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-06-23
    Nick Salter

    The Burau representation is a fundamental bridge between the braid group and diverse other topics in mathematics. A 1974 question of Birman asks for a description of the image; in this paper we give an approximate answer. Since a 1984 paper of Squier it has been known that the Burau representation preserves a certain Hermitian form. We show that the Burau image is dense in this unitary group relative

    更新日期:2020-06-23
  • Double branched covers of tunnel number one knots
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-06-22
    Yeonhee Jang, Luisa Paoluzzi

    We provide criteria ensuring that a tunnel number one knot K is not determined by its double branched cover, in the sense that the double branched cover is also the double branched cover of a knot \(K'\) not equivalent to K.

    更新日期:2020-06-22
  • Secant planes of a general curve via degenerations
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-06-19
    Ethan Cotterill, Xiang He, Naizhen Zhang

    We study linear series on a general curve of genus g, whose images are exceptional with respect to their secant planes. Each such exceptional secant plane is algebraically encoded by an included linear series, whose number of base points computes the incidence degree of the corresponding secant plane. With enumerative applications in mind, we construct a moduli scheme of inclusions of limit linear

    更新日期:2020-06-22
  • Horizon saddle connections, quasi-Hopf surfaces and Veech groups of dilation surfaces
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-06-18
    Guillaume Tahar

    Dilation surfaces are generalizations of translation surfaces where the geometric structure is modelled on the complex plane up to affine maps whose linear part is real. They are the geometric framework to study suspensions of affine interval exchange maps. However, though the \(SL(2,\mathbb {R})\)-action is ergodic in connected components of strata of translation surfaces, there may be mutually disjoint

    更新日期:2020-06-19
  • Convergence of locally homogeneous spaces
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-06-08
    Francesco Pediconi

    We study three different topologies on the moduli space \(\mathcal {H}^\mathrm{loc}_m\) of equivariant local isometry classes of m-dimensional locally homogeneous Riemannian spaces. As an application, we provide the first examples of locally homogeneous spaces converging to a limit space in the pointed \(\mathcal {C}^{k,\alpha }\)-topology, for some \(k>1\), which do not admit any convergent subsequence

    更新日期:2020-06-08
  • Rigid isotopy classification of generic rational curves of degree 5 in the real projective plane
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-05-29
    Andrés Jaramillo Puentes

    In this article we obtain the rigid isotopy classification of generic rational curves of degre 5 in \({\mathbb {R}}{\mathbb {P}}^{2}\). In order to study the rigid isotopy classes of nodal rational curves of degree 5 in \({\mathbb {R}}{\mathbb {P}}^{2}\), we associate to every real rational nodal quintic curve with a marked real nodal point a nodal trigonal curve in the Hirzebruch surface \(\Sigma

    更新日期:2020-05-29
  • Algebraic models of the line in the real affine plane
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-05-27
    Adrien Dubouloz, Frédéric Mangolte

    We study smooth rational closed embeddings of the real affine line into the real affine plane, that is algebraic rational maps from the real affine line to the real affine plane which induce smooth closed embeddings of the real euclidean line into the real euclidean plane. We consider these up to equivalence under the group of birational automorphisms of the real affine plane which are diffeomorphisms

    更新日期:2020-05-27
  • Automorphism group of a moduli space of framed bundles over a curve
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-05-25
    David Alfaya, Indranil Biswas

    Let X be a smooth complex projective curve, and let \(x\,\in \, X\) be a point. We compute the automorphism group of the moduli space of framed vector bundles on X of rank \(r\, \ge \, 2\) with a framing over x. It is shown that this automorphism group is generated by the following three: (1) pullbacks using automorphisms of the curve X that fix the marked point x, (2) tensorization with certain line

    更新日期:2020-05-25
  • Space of minimal discs and its compactification
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-05-25
    Paul Creutz

    We investigate the class of geodesic metric discs satisfying a uniform quadratic isoperimetric inequality and uniform bounds on the length of the boundary circle. We show that the closure of this class as a subset of Gromov-Hausdorff space is intimately related to the class of geodesic metric disc retracts satisfying comparable bounds. This kind of discs naturally come up in the context of the solution

    更新日期:2020-05-25
  • The maximal injectivity radius of hyperbolic surfaces with geodesic boundary
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-05-21
    Jason DeBlois, Kim Romanelli

    We give sharp upper bounds on the injectivity radii of complete hyperbolic surfaces of finite area with some geodesic boundary components. The given bounds are over all such surfaces with any fixed topology; in particular, boundary lengths are not fixed. This extends the first author’s earlier result to the with-boundary setting. In the second part of the paper we comment on another direction for extending

    更新日期:2020-05-21
  • Fano manifolds of coindex three admitting nef tangent bundle
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-05-19
    Kiwamu Watanabe

    We prove that any Fano manifold of coindex three admitting nef tangent bundle is homogeneous.

    更新日期:2020-05-19
  • Equidistribution of families of expanding horospheres on moduli spaces of hyperbolic surfaces
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-05-13
    Francisco Arana-Herrera

    Given a simple closed curve \(\gamma \) on a connected, oriented, closed surface S of negative Euler characteristic, Mirzakhani showed that the set of points in the moduli space of hyperbolic structures on S having a simple closed geodesic of length L of the same topological type as \(\gamma \) equidistributes with respect to a natural probability measure as \(L \rightarrow \infty \). We prove several

    更新日期:2020-05-13
  • On the quasi-isometric and bi-Lipschitz classification of 3D Riemannian Lie groups
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-04-28
    Katrin Fässler, Enrico Le Donne

    This note is concerned with the geometric classification of connected Lie groups of dimension three or less, endowed with left-invariant Riemannian metrics. On the one hand, assembling results from the literature, we give a review of the complete classification of such groups up to quasi-isometries and we compare the quasi-isometric classification with the bi-Lipschitz classification. On the other

    更新日期:2020-04-28
  • Mixed tête-à-tête twists as monodromies associated with holomorphic function germs
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-04-23
    Pablo Portilla Cuadrado, Baldur Sigurðsson

    Tête-à-tête graphs were introduced by N. A’Campo in 2010 with the goal of modeling the monodromy of isolated plane curves. Mixed tête-à-tête graphs provide a generalization which define mixed tête-à-tête twists, which are pseudo-periodic automorphisms on surfaces. We characterize the mixed tête-à-tête twists as those pseudo-periodic automorphisms that have a power which is a product of right-handed

    更新日期:2020-04-23
  • Presentations for the Euclidean Picard modular groups
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-04-22
    David Polletta

    Mark and Paupert devised a general method for obtaining presentations for arithmetic non-cocompact lattices, \(\Gamma \), in isometry groups of negatively curved symmetric spaces. The method involves a classical theorem of Macbeath applied to a \(\Gamma \)-invariant covering by horoballs of the negatively curved symmetric space upon which \(\Gamma \) acts. In this paper, we will discuss the application

    更新日期:2020-04-22
  • Linear representations of $$\text {Aut}(F_r)$$Aut(Fr) on the homology of representation varieties
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-04-16
    Yael Algom-Kfir, Asaf Hadari

    Let G be a compact semisimple linear Lie group. We study the action of \(\text {Aut}(F_r)\) on the space \(H_*(G^r; {\mathbb {Q}})\). We compute the image of this representation and prove that it only depends on the rank of \({\mathfrak {g}}\). We show that the kernel of this representation is always the Torrelli subgroup \(\text {IA}_r\) of \(\text {Aut}(F_r)\).

    更新日期:2020-04-16
  • Flag structures on real 3-manifolds
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-04-15
    E. Falbel, J. M. Veloso

    We define flag structures on a real three manifold M as the choice of two complex lines on the complexified tangent space at each point of M. We suppose that the plane field defined by the complex lines is a contact plane and construct an adapted connection on an appropriate principal bundle. This includes path geometries and CR structures as special cases. We prove that the null curvature models are

    更新日期:2020-04-15
  • Connection blocking in $$\text {SL}(n,\mathbb {R})$$SL(n,R) quotients
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-04-11
    Mohammadreza Bidar

    Let G be a connected Lie group and \(\varGamma \subset G\) a lattice. Connection curves of the homogeneous space \(M=G/\varGamma \) are the orbits of one parameter subgroups of G. To block a pair of points \(m_1,m_2 \in M\) is to find a finite set \(B \subset M{\setminus } \{m_1, m_2 \}\) such that every connecting curve joining \(m_1\) and \(m_2\) intersects B. The homogeneous space M is blockable

    更新日期:2020-04-11
  • Higher symmetries of symplectic Dirac operator
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-04-09
    Petr Somberg, Josef Šilhan

    We construct in projective differential geometry of the real dimension 2 higher symmetry algebra of the symplectic Dirac operator acting on symplectic spinors. The higher symmetry differential operators correspond to the solution space of a class of projectively invariant overdetermined operators of arbitrarily high order acting on symmetric tensors. The higher symmetry algebra structure corresponds

    更新日期:2020-04-09
  • Finite quotients of braid groups
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-02-14
    Alice Chudnovsky, Kevin Kordek, Qiao Li, Caleb Partin

    We derive a lower bound on the size of finite non-cyclic quotients of the braid group that is superexponential in the number of strands. We also derive a similar lower bound for nontrivial finite quotients of the commutator subgroup of the braid group.

    更新日期:2020-02-14
  • Automorphisms of the Hilbert schemes of n points of a rational surface and the anticanonical Iitaka dimension
    Geom. Dedicata. (IF 0.584) Pub Date : 2020-01-08
    Taro Hayashi

    The purpose of this paper is to investigate relationship between the automorphism group of a rational surface and that of its Hilbert scheme of n points.

    更新日期:2020-01-08
  • The action dimension of Artin groups
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-12-23
    Giang Le

    The action dimension of a discrete group G is the minimum dimension of a contractible manifold, which admits a proper G-action. In this paper, we study the action dimension of general Artin groups. The main result is that if an Artin group with the nerve L of dimension n for \(n \ne 2\) satisfies the \(K(\pi , 1)\)-Conjecture and the top cohomology group of L with \({\mathbb {Z}}\)-coefficients is

    更新日期:2019-12-23
  • Embedding non-projective Mori dream space
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-12-13
    Michele Rossi

    This paper is devoted to extend some Hu–Keel results on Mori dream spaces (MDS) beyond the projective setup. Namely, \(\mathbb {Q}\)-factorial algebraic varieties with finitely generated class group and Cox ring, here called weak Mori dream spaces (wMDS), are considered. Conditions guaranteeing the existence of a neat embedding of a (completion of a) wMDS into a complete toric variety are studied,

    更新日期:2019-12-13
  • Group Actions on cyclic covers of the projective line
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-12-07
    Aristides Kontogeorgis, Panagiotis Paramantzoglou

    We use tools from combinatorial group theory in order to study actions of three types on groups acting on a curve, namely the automorphism group of a compact Riemann surface, the mapping class group acting on a surface (which now is allowed to have some points removed) and the absolute Galois group \(\mathrm {Gal}({\bar{{\mathbb {Q}}}}/{\mathbb {Q}})\) in the case of cyclic covers of the projective

    更新日期:2019-12-07
  • Quasi-morphisms on contactomorphism groups and Grassmannians of 2-planes
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-12-02
    Frol Zapolsky

    We construct a natural prequantization space over a monotone product of a toric manifold and an arbitrary number of complex Grassmannians of 2-planes in even-dimensional complex spaces, and prove that the universal cover of the identity component of the contactomorphism group of its total space carries a nonzero homogeneous quasi-morphism. The construction uses Givental’s nonlinear Maslov index and

    更新日期:2019-12-02
  • The horofunction boundary of the infinite dimensional hyperbolic space
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-11-27
    Floris Claassens

    In this paper we give a complete description of the horofunction boundary of the infinite dimensional real hyperbolic space, and characterise its Busemann points.

    更新日期:2019-11-27
  • New construction of ruled real hypersurfaces in a complex hyperbolic space and its applications
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-11-22
    Makoto Kimura, Sadahiro Maeda, Hiromasa Tanabe

    A ruled real hypersurface in a complex space form is a real hypersurface having a codimension one foliation by totally geodesic complex hyperplanes of the ambient space. Our main purpose of this paper is to introduce a new viewpoint to investigate such hypersurfaces in complex hyperbolic space \(\mathbb {CH}^n\). As an application, we study minimal ruled real hypersurfaces in \(\mathbb {CH}^n\) and

    更新日期:2019-11-22
  • Primary singularities of vector fields on surfaces
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-11-22
    M. W. Hirsch, F. J. Turiel

    Unless another thing is stated one works in the \(C^\infty \) category and manifolds have empty boundary. Let X and Y be vector fields on a manifold M. We say that Y tracks X if \([Y,X]=fX\) for some continuous function \(f:M\rightarrow \mathbb {R}\). A subset K of the zero set \({\mathsf {Z}} (X)\) is an essential block for X if it is non-empty, compact, open in \({\mathsf {Z}}(X)\) and its Poincaré-Hopf

    更新日期:2019-11-22
  • Existence of two-parameter crossings, with applications
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-11-21
    Jonathan D. Williams

    A Morse 2-function is a generic smooth map f from a manifold M of arbitrary finite dimension to a surface B. Its critical set maps to an immersed collection of cusped arcs in B. The aim of this paper is to explain exactly when it is possible to move these arcs around in B by a homotopy of f and to give a library of examples when M is a closed 4-manifold. The last two sections give applications to the

    更新日期:2019-11-21
  • Four-manifolds with harmonic 2-forms of constant length
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-11-09
    Inyoung Kim

    It was shown by Seaman that if a compact, connected, oriented, riemannian 4-manifold (M, g) of positive sectional curvature admits a harmonic 2-form of constant length, then M has definite intersection form and such a harmonic form is unique up to constant multiples. In this paper, we show that such a manifold is diffeomorphic to \(\mathbb {CP}_{2}\) with a slightly weaker curvature hypothesis and

    更新日期:2019-11-09
  • Isometry groups of closed Lorentz 4-manifolds are Jordan
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-11-01
    Ignasi Mundet i Riera

    We prove that for any closed Lorentz 4-manifold (M, g) the isometry group \({\text {Isom}}(M,g)\) is Jordan. Namely, there exists a constant C (depending on M and g) such that any finite subgroup \(\Gamma \le {\text {Isom}}(M,g)\) has an abelian subgroup \(A\le \Gamma \) satisfying \([\Gamma :A]\le C\).

    更新日期:2019-11-01
  • Distance difference representations of Riemannian manifolds
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-10-30
    Sergei Ivanov

    Let M be a complete Riemannian manifold and \(F\subset M\) a set with a nonempty interior. For every \(x\in M\), let \(D_x\) denote the function on \(F\times F\) defined by \(D_x(y,z)=d(x,y)-d(x,z)\) where d is the geodesic distance in M. The map \(x\mapsto D_x\) from M to the space of continuous functions on \(F\times F\), denoted by \({\mathcal {D}}_F\), is called a distance difference representation

    更新日期:2019-10-30
  • Foliations on $$\mathbb {CP}^2$$ CP 2 with a unique singular point without invariant algebraic curves
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-10-29
    Claudia R. Alcántara, Rubí Pantaleón-Mondragón

    We prove that a foliation on \(\mathbb {CP}^2\) of degree d with a singular point of type saddle-node with Milnor number \(d^2+d+1\) does not have invariant algebraic curves. We give a family of this kind of foliations. We also present a family of foliations of degree d with a unique nilpotent singularity without invariant algebraic curves for d odd greater than 1. Finally we prove that the space of

    更新日期:2019-10-29
  • Configurations of flags in orbits of real forms
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-10-24
    Elisha Falbel, Marco Maculan, Giulia Sarfatti

    In this paper we start the study of configurations of flags in closed orbits of real forms using mainly tools of GIT. As an application, using cross ratio coordinates for generic configurations, we identify boundary unipotent representations of the fundamental group of the figure eight knot complement into real forms of \({{\,\mathrm{PGL}\,}}(4,{\mathbb {C}})\).

    更新日期:2019-10-24
  • Ricci flow on surfaces of revolution: an extrinsic view
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-10-24
    Vincent E. Coll, Jeff Dodd, David L. Johnson

    A Ricci flow (M, g(t)) on an n-dimensional Riemannian manifold M is an intrinsic geometric flow. A family of smoothly embedded submanifolds \((S(t), g_E)\) of a fixed Euclidean space \(E = \mathbb {R}^{n+k}\) is called an extrinsic representation in \(\mathbb {R}^{n+k}\) of (M, g(t)) if there exists a smooth one-parameter family of isometries \((S(t), g_E) \rightarrow (M, g(t))\). When does such a

    更新日期:2019-10-24
  • Failure of the $$L^1$$ L 1 pointwise ergodic theorem for $$\mathrm {PSL}_2(\mathbb {R})$$ PSL 2 ( R )
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-10-19
    Lewis Bowen, Peter Burton

    Amos Nevo established the pointwise ergodic theorem in \(L^p\) for measure-preserving actions of \(\mathrm {PSL}_2(\mathbb {R})\) on probability spaces with respect to ball averages and every \(p>1\). This paper shows by explicit example that Nevo’s Theorem cannot be extended to \(p=1\).

    更新日期:2019-10-19
  • On hyperbolicity and virtual freeness of automorphism groups
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-10-16
    Olga Varghese

    We show that word hyperbolicity of automorphism groups of graph products \(G_\Gamma \) and of Coxeter groups \(W_\Gamma \) depends strongly on the shape of the defining graph \(\Gamma \). We also characterize those \(\mathrm{Aut}(G_\Gamma )\) and \(\mathrm{Aut}(W_\Gamma )\) in terms of \(\Gamma \) that are virtually free.

    更新日期:2019-10-16
  • Plane curves with three syzygies, minimal Tjurina curves, and nearly cuspidal curves
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-10-09
    Alexandru Dimca, Gabriel Sticlaru

    We start the study of reduced complex projective plane curves, whose Jacobian syzygy module has 3 generators. Among these curves one finds the nearly free curves introduced by the authors, and the plus-one generated line arrangements introduced by Takuro Abe. All the Thom–Sebastiani type plane curves, and more generally, any curve whose global Tjurina number is equal to a lower bound given by A. du

    更新日期:2019-10-09
  • On 2-knots and connected sums with projective planes
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-09-25
    Vincent Longo

    In this paper, we generalize a result of Satoh to show that for any odd natural n, the connected sum of the n-twist spun sphere of a knot K and an unknotted projective plane in the 4-sphere is equivalent to the same unknotted projective plane. We additionally provide a fix to a small error in Satoh’s proof of the case that K is a 2-bridge knot.

    更新日期:2019-09-25
  • Finding simple curves in surface covers is undecidable
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-09-17
    Ingrid Irmer

    It is shown that various questions about the existence of simple closed curves in normal subgroups of surface groups are undecidable.

    更新日期:2019-09-17
  • Collapsibility of CAT(0) spaces
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-09-10
    Karim Adiprasito, Bruno Benedetti

    Collapsibility is a combinatorial strengthening of contractibility. We relate this property to metric geometry by proving the collapsibility of any complex that is \(\mathrm {CAT}(0)\) with a metric for which all vertex stars are convex. This strengthens and generalizes a result by Crowley. Further consequences of our work are: (1) All \(\mathrm {CAT}(0)\) cube complexes are collapsible. (2) Any triangulated

    更新日期:2019-09-10
  • Ideal polyhedral surfaces in Fuchsian manifolds
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-09-07
    Roman Prosanov

    Let \(S_{g,n}\) be a surface of genus \(g > 1\) with \(n>0\) punctures equipped with a complete hyperbolic cusp metric. Then it can be uniquely realized as the boundary metric of an ideal Fuchsian polyhedron. In the present paper we give a new variational proof of this result. We also give an alternative proof of the existence and uniqueness of a hyperbolic polyhedral metric with prescribed curvature

    更新日期:2019-09-07
  • Cohomogeneity one actions on the three-dimensional Einstein universe
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-09-01
    M. Hassani, P. Ahmadi

    The aim of this paper is to classify the cohomogeneity one conformal actions on the 3-dimensional Einstein universe \(\mathbb {E}{\mathrm {in}}^{1,2}\), up to orbit equivalence. In a recent paper (Hassani in C R Acad Sci Paris Ser I 355:1133–1137, 2017. https://doi.org/10.1016/j.crma.2017.10.003), we studied the unique (up to conjugacy) irreducible action of \({\mathrm {PSL}}(2,\mathbb {R})\) on \(\mathbb

    更新日期:2019-09-01
  • Construction of Milnorian representations
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-08-30
    Ilia Smilga

    We prove a partial converse to the main theorem of the author’s previous paper Proper affine actions: a sufficient criterion (submitted; available at arXiv:1612.08942). More precisely, let G be a semisimple real Lie group with a representation \(\rho \) on a finite-dimensional real vector space V, that does not satisfy the criterion from the previous paper. Assuming that \(\rho \) is irreducible and

    更新日期:2019-08-30
  • Finite rigid sets in curve complexes of nonorientable surfaces
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-08-29
    Sabahattin Ilbira, Mustafa Korkmaz

    A rigid set in a curve complex of a surface is a subcomplex such that every locally injective simplicial map from the set into the curve complex is induced by a homeomorphism of the surface. In this paper, we find finite rigid sets in the curve complexes of connected nonorientable surfaces of genus g with n holes for \(g+n \ne 4\).

    更新日期:2019-08-29
  • A note on invariant constant curvature immersions in Minkowski space
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-08-28
    François Fillastre, Graham Smith

    Let S be a compact, orientable surface of hyperbolic type. Let \((k_+,k_-)\) be a pair of negative numbers and let \((g_+, g_-)\) be a pair of marked metrics over S of constant curvature equal to \(k_+\) and \(k_-\) respectively. Using a functional introduced by Bonsante, Mondello and Schlenker, we show that there exists a unique affine deformation \(\Gamma :=(\rho ,\tau )\) of a Fuchsian group such

    更新日期:2019-08-28
  • A surface with discontinuous isoperimetric profile and expander manifolds
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-08-03
    Panos Papasoglu, Eric Swenson

    We construct sequences of ‘expander manifolds’ and we use them to show that there is a complete connected 2-dimensional Riemannian manifold with discontinuous isoperimetric profile, answering a question of Nardulli and Pansu. Using expander manifolds in dimension 3 we show that for any \(\epsilon , M>0\) there is a Riemannian 3-sphere S of volume 1, such that any (not necessarily connected) surface

    更新日期:2019-08-03
  • Cusp shapes of Hilbert–Blumenthal surfaces
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-07-29
    Joseph Quinn, Alberto Verjovsky

    We introduce a new fundamental domain \(\mathscr {R}_n\) for a cusp stabilizer of a Hilbert modular group \(\Gamma \) over a real quadratic field \(K=\mathbb {Q}(\sqrt{n})\). This is constructed as the union of Dirichlet domains for the maximal unipotent group, over the leaves in a foliation of \(\mathcal {H}^2\times \mathcal {H}^2\). The region \(\mathscr {R}_n\) is the product of \(\mathbb {R}^+\)

    更新日期:2019-07-29
  • New horoball packing density lower bound in hyperbolic 5-space
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-07-20
    Robert Thijs Kozma, Jenő Szirmai

    We determine the optimal horoball packings of the asymptotic or Koszul-type Coxeter simplex tilings of hyperbolic 5-space, where the symmetries of the packings are derived from Coxeter groups. The packing density \(\varTheta = \frac{5}{7 \zeta (3)} \approx 0.5942196502\ldots \) is optimal and realized in eleven cases in a commensurability class of arithmetic Coxeter tilings. For the optimal packing

    更新日期:2019-07-20
  • On local isometric embeddings of three-dimensional Lie groups
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-07-17
    Yoshio Agaoka, Takahiro Hashinaga

    Due to Janet–Cartan’s theorem, any analytic Riemannian manifolds can be locally isometrically embedded into a sufficiently high dimensional Euclidean space. However, for an individual Riemannian manifold (M, g), it is in general hard to determine the least dimensional Euclidean space into which (M, g) can be locally isometrically embedded, even in the case where (M, g) is homogeneous. In this paper

    更新日期:2019-07-17
  • The least-area tetrahedral tile of space
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-07-10
    Eliot Bongiovanni, Alejandro Diaz, Arjun Kakkar, Nat Sothanaphan

    We determine the least-area unit-volume tetrahedral tile of Euclidean space, without the constraint of Gallagher et al. that the tiling uses only orientation-preserving images of the tile. The winner remains Sommerville’s type 4v.

    更新日期:2019-07-10
  • Generalized vector cross products and Killing forms on negatively curved manifolds
    Geom. Dedicata. (IF 0.584) Pub Date : 2019-07-08
    María Laura Barberis, Andrei Moroianu, Uwe Semmelmann

    Motivated by the study of Killing forms on compact Riemannian manifolds of negative sectional curvature, we introduce the notion of generalized vector cross products on \({\mathbb {R}}^n\) and give their classification. Using previous results about Killing tensors on negatively curved manifolds and a new characterization of \(\mathrm {SU}(3)\)-structures in dimension 6 whose associated 3-form is Killing

    更新日期:2019-07-08
Contents have been reproduced by permission of the publishers.
导出
全部期刊列表>>
欢迎访问IOP中国网站
自然职场线上招聘会
GIANT
产业、创新与基础设施
自然科研线上培训服务
材料学研究精选
胸腔和胸部成像专题
屿渡论文,编辑服务
何川
苏昭铭
陈刚
姜涛
李闯创
李刚
北大
隐藏1h前已浏览文章
课题组网站
新版X-MOL期刊搜索和高级搜索功能介绍
ACS材料视界
天合科研
x-mol收录
上海纽约大学
陈芬儿
厦门大学
何振宇
史大永
吉林大学
卓春祥
张昊
杨中悦
试剂库存
down
wechat
bug