BUSCADOR RECOLECTA

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Periodic solutions of second-order differential inclusions systems with p-Laplacian

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Paşca, Daniel

Some existence results are obtained for periodic solutions of nonautonomous second-order differential inclusions systems with p-Laplacian



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The orthogonal subcategory problem in homotopy theory

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Casacuberta i Vergés, Carles, Chorny, Boris

It is known that, in a locally presentable category, localization exists with respect to every set of morphisms, while the statement that localization with respect to every (possibly proper) class of morphisms exists in locally presentable categories is equivalent to a large-cardinal axiom from set theory. One proves similarly, on one hand, that homotopy localization exists with respect to sets of maps in every cofibrantly generated, left proper, simplicial model category M whose underlying...



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Global eriodicity and complete integrability of discrete dynamical systems

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Cima, Anna, Gasull i Embid, Armengol, Mañosa, Víctor

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Embedding theorems of funcitional classes, III

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Simonov, Boris V., Tikhonov, Sergey Yu.

In this paper we obtain the necessary and sufficient conditions for embedding results of different function classes. The main result is a criterion for embedding theorems for the so-called generalized Weyl-Nikol'skii class and the generalized Lipschitz class. To define the Weyl-Nikol'skii class, we use the concept of a (λ,β)-derivative, which is a generalization of the derivative in the sense of Weyl. As corollaries, we give estimates of norms and moduli of smoothness of transformed...



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The unbounded dead-end depth propertie is not a group invariant

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Riley, Tim, Warshall, Andrew D.

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Examples of retracts in a free group that are not the fixed subgroup of any group of automorphisms

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Ciobanu, Laura, Dicks, Warren

Let F be a free group of rank at least three. We show that some retracts of F previously studied by Martino-Ventura are not equal to the fixed subgroup of any group of automorphisms of F. This shows that, in F, there exist subgroups that are equal to the fixed subgroup of some set of endomorphisms but are not equal to the fixed subgroup of any set of automorphisms. Moreover, we determine the Galois monoids of these retracts, where, by the Galois monoid of a subgroup H of F, we mean the monoid...



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On the set of subrings wich are directed unions of Artinian subrings

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Karim, Darioush, Zarzuela, Santiago

The paper contributes to the investigation of zero-dimensional rings which can be written as a directed union of Artinian subrings. We give conditions on DU(R) in order to be nonempty.



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Periodic orbits of the planar collision restricted 3-body problem

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Llibre i Saló, Jaume, Paşca, Daniel

Using the continuation method we prove that the circular and the elliptic symmetric periodic orbits of the planar rotating Kepler problem can be continued into periodic orbits of the planar collision restricted 3–body problem. Additionally, we also continue to this restricted problem the so called “comets orbits”.



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Some remarks on the class of continuous (Semi-) strictcly quasiconvex functions

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Daniilidis, Aris, García Ramos, Yboon

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In search of mathematical primitives for deriving universal projective hash families

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
González Vasco, Maria Isabel, Villar, Jorge L.

We provide some guidelines for deriving new projective hash families of cryptographic interest. Our main building blocks are so called group action systems; we explore what properties of this mathematical primitives may lead to the construction of cryptographically useful projective hash families. We point out different directions towards new constructions, deviating from known proposals arising from Cramer and Shoup's seminal work.



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The automorphism group of a free-by-cyclic group in rank 2

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Bogopolski, O., Martino, Armando, Ventura, Enric

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Linear stochastic differential algebraic equations with constant coefficients

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Alabert, Aureli, Ferrante, Marco

We consider linear stochastic differential-algebraic equations with constant coefficients and additive white noise. Due to the nature of this class of equations, the solution must be defined as a generalised process (in the sense of Dawson and Fernique). We provide sufficient conditions for the law of the variables of the solution process to be absolutely continuous with respect to Lebesgue measure.



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Clarke critical values of subanalytic Lipschitz continuous functions

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Bolte, Jerôme, Daniilidis, Aris, Lewis, Adrian S., Shiota, Masashiro

We prove that any subanalytic locally Lipschitz function has the Sard property. Such functions are typically nonsmooth and their lack of regularity necessitates the choice of some generalized notion of gradient and of critical point. In our framework these notions are defined in terms of the Clarke and of the convex-stable subdifferentials. The main result of this note asserts that for any subanalytic locally Lipschitz function the set of its Clarke critical values is locally finite. The proof...



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Mixed Hodge structures and vector bundles on the projective Plane I

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Penacchio, Olivier

We describe an equivalence of categories between the category of mixed Hodge structures and a category of vector bundles on the toric complex projective plane which verify some semistability condition. We then apply this correspondence to define an invariant which generalises the notion of R-split mixed Hodge structure and compute extensions in the category of mixed Hodge structures in terms of extensions of the corresponding vector bundles. We also give a relative version of this...



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Polynomial-time complexity for instances of the endomorphism problem in free groups

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Ciobanu, Laura

We say the endomorphism problem is solvable for an element W in a free group F if it can be decided effectively whether, given U in F, there is an endomorphism Φ of F sending W to U. This work analyzes an approach due to C. Edmunds and improved by C. Sims. Here we prove that the approach provides an efficient algorithm for solving the endomorphism problem when W is a two- generator word. We show that when W is a two-generator word this algorithm solves the problem in time polynomial in the...



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Distortion of surface groups in Cat (0) free-by-cyclic groups

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Barnard, Josh, Brady, Noel

Given a non-positively curved 2-complex with a circle-valued Morse function satisfying some extra combinatorial conditions, we describe how to locally isometrically embed this in a larger non- positively curved 2-complex with free-by-cyclic fundamental group. This embedding procedure is used to produce examples of CAT(0) free-by-cyclic groups that contain closed hyperbolic surface subgroups with polynomial distortion of arbitrary degree. We also produce examples of CAT(0) hyperbolic free-by-...



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On the number of limit cycles bifurcating from a non-global degenerated center

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Gasull i Embid, Armengol, Li, Chengzhi, Liu, Changjian

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Embedding theorems of function classes, IV

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Tikhonov, Sergey Yu.

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RECASTING THE ELLIOTT CONJECTURE

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Perera Domènech, Francesc, Toms, Andrew S.

Let A be a simple, unital, finite, and exact C*-algebra which absorbs the Jiang-Su algebra Z tensorially. We prove that the Cuntz semigroup of A admits a complete order embedding into an ordered semigroup which is obtained from the Elliott invariant in a functorial manner. We conjecture that this embedding is an isomor phism, and prove the conjecture in several cases. In these same cases - Z-stable algebras all - we prove that the Elliott conjecture in its strongest form is equivalent to a...



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Periodic solutions for nonautonomous second order differential inclusions systems with p- Laplacian

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Paşca, Daniel

Using the nonsmooth variant of minimax point theorems, some existence results are obtained for periodic solutions of nonautonomous second-order differential inclusions systems with p-Laplacian.



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Growth of positive words and lower bounds of the growth rate for Thompson's group (F)p

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Burillo Puig, Josep, Guba, Víctor S.

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Bounding right-arm rotation distances

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Cleary, Sean, Taback, Jennifer

Rotation distance quantifies the difference in shape between two rooted binary trees of the same size by counting the minimum number of elementary changes needed to transform one tree to the other. We describe several types of rotation distance, and provide upper bounds on distances between trees with a fixed number of nodes with respect to each type. These bounds are obtained by relating each restricted rotation distance to the word length of elements of Thompson's group F with respect to...



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Embedding theorems of function classes, II

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Tikhonov, Sergey Yu.

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Computational explorations in Thompson's group F

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Burillo Puig, Josep, Cleary, Sean, Wiest, Bertold

Here we describe the results of some computational explorations in Thompson's group F. We describe experiments to estimate the cogrowth of F with respect to its standard finite generating set, designed to address the subtle and difficult question whether or not Thompson's group is amenable. We also describe experiments to estimate the exponential growth rate of F and the rate of escape of symmetric random walks with respect to the standard generating set.



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A topological proof that surface relators are test words

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Turner, Edward C.

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On Hyperbolic once-punctured-torus bundles II. Fractal tessellations of the plane

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Cannon, James W., Dicks, Warren

We describe fractal tessellations of the complex plane that arise naturally from Cannon-Thurston maps associated to complete, hyperbolic, once-punctured-torus bundles. We determine the symmetry groups of these tessellations.



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Contractions in the 2-wasserstein lenght space and thermalization of granular media

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Carrillo, José A., McCann, Robert, J., Villani, Cédric

An algebraic decay rate is derived which bounds the time required for velocities to equilibrate in a spatially homogeneous flow-through model representing the continuum limit of a gas of particles interacting through slightly inelastic collisions. This rate is obtained by reformulating the dynamical problem as the gradient flow of a convex energy on an infinite-dimensional manifold. An abstract theory is developed for gradient flows in length spaces, which shows how degenerate convexity (or...



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Combinatorial and metric properties of Thompson's group T

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Burillo Puig, Josep, Cleary, Sean, Stein, Melanie, Taback, Jennifer

We discuss metric and combinatorial properties of Thompson's group T, such as the normal forms for elements and uniqueness of tree pair diagrams. We relate these properties to those of Thompson's group F when possible, and highlight combinatorial differences between the two groups. We define a set of unique normal forms for elements of T arising from minimal factorizations of elements into convenient pieces. We show that the number of carets in a reduced representative of T estimates...



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A proof that all Seifert 3-manifold groups and all virtual surface groups are conjugacy separable

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Martino, Armando

We prove that the fundamental group of any Seifert 3-manifold is conjugacy separable. That is, conjugates may be distinguished infinite quotients or, equivalently, conjugacy classes are closed in the pro-finite topology.



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The Zariski-Lefschetz principle for higher homotopy groups of nongeneric pencils

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Tibăr, Mihai

We prove a general Zariski-van Kampen-Lefschetz type theorem for higher homotopy groups of generic and nongeneric pencils on singular open complex spaces.



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Intermediate asymptotics beyond homogeneity and self-similarity: long time behavior for [formula]

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Carrillo, José A., Di Francesco, Marco, Gualdani, Maria P.

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Contractive metrics for a Boltzmann equation for granular gases: diffusive equilibriaThe Patterson-Sullivan embedding and minimal volume entropy for outer space

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Bisi, M., Carrillo, José A., Toscani, Giuseppe

We quantify the long-time behavior of a system of (partially) inelastic particles in a stochastic thermostat by means of the contractivity of a suitable metric in the set of probability measures. Existence, uniqueness, boundedness of moments and regularity of a steady state are derived from this basic property. The solutions of the kinetic model are proved to converge exponentially as t→ ∞ to this diffusive equilibrium in this distance metrizing the weak convergence of measures. Then, we prove...



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The Patterson-Sullivan embedding and minimal volume entropy for outer space

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Kapovich, Ilya, Smirnova-Nagnibeda, Tatian

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Periodic orbits near a heteroclinic loop formed by one dimensional orbit and a 2-dimensional manifold: application to the charged collinear 3-body problem

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Llibre i Saló, Jaume, Paşca, Daniel

The paper is devoted to the study of a type of differential systems which appear usually in the study of some Hamiltonian systems with 2 degrees of freedom. We prove the existence of infinitely many periodic orbits on each negative energy level. All these periodic orbits pass near the total collision. Finally we apply these results to study the existence of periodic orbits in the charged collinear 3–body problem.



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Free and fragmenting filling length

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Bridson, Martin, R., Riley, Tim

The filling length of an edge-circuit η in the Cayley 2-complex of a finite presentation of a group is the minimal integer length L such that there is a combinatorial null-homotopy of η down to a base point through loops of length at most L. We introduce similar notions in which the full-homotopy is not required to fix a base point, and in which the contracting loop is allowed to bifurcate. We exhibit a group in which the resulting filling invariants exhibit dramatically different behaviour to...



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The period function of the generalized Lotka-Volterra centers

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Villadelprat Yagüe, Jordi

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Embedding theorems of function classes, I

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Simonov, Boris V., Tikhonov, Sergey Yu.

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The complexity of random ordered structures

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Spencer, Joel, H., St. John, Katherine

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Stability and asymptotic analysis of a fluid-particle interaction model

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Carrillo, José A., Goudon, Thierry

We are interested in coupled microscopic/macroscopic models describing the evolution of particles dispersed in a fluid. The system consists in a Vlasov-Fokker-Planck equation to describe the microscopic motion of the particles coupled to the Euler equations for a compressible fluid. We investigate dissipative quantities, equilibria and their stability properties and the role of external forces. We also study some asymptotic problems, their equilibria and stability and the derivation of...



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Metrics on diagram groups and uniform embeddings in a Hilbert space

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Arzhantseva, Goulnara N., Guba, Víctor S., Sapir, Mark V.

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Semidiscretization and long-time asymptotics of nonlinear diffusion equations

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Carrillo, José A., Di Francesco, Marco, Gualdani, Maria P.

We review several results concerning the long time asymptotics of nonlinear diffusion models based on entropy and mass transport methods. Semidiscretization of these nonlinear diffusion models are proposed and their numerical properties analysed. We demonstrate the long time asymptotic results by numerical simulation and we discuss several open problems based on these numerical results. We show that for general nonlinear diffusion equations the long-time asymptotics can be characterized in...



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Testing Cayley graph densities

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Arzhantseva, Goulnara N., Guba, Víctor S., Lustig, Martin, Préaux, Jean-Philippe

We present a computer-assisted analysis of combinatorial properties of the Cayley graphs of certain finitely generated groups: Given a group with a finite set of generators, we study the density of the corresponding Cayley graph, that is, the least upper bound for the average vertex degree (= number of adjacent edges) of any finite subgraph. It is known that an m-generated group is amenable if and only if the density of the corresponding Cayley graph equals to 2m. We test amenable and non-...



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Generalized property R and the Schoenflies Conjecture

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Scharlemann, Martin

There is a relation between the generalized Property R Conjecture and the Schoenflies Conjecture that suggests a new line of attack on the latter. The new approach gives a quick proof of the genus 2 Schoenflies Conjecture and suffices to prove the genus 3 case, even in the absence of new progress on the generalized Property R Conjecture.



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Pure braid subgroups of braided Thompson's groups

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Brady, Thomas, Burillo Puig, Josep, Cleary, Sean, Stein, Melanie

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Absolute type shaft encoding using LFSR

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Ventura, Enric, Fuertes i Armengol, Josep M., Balle, Borja

Maximal-length binary sequences have been known for a long time. They have many interesting properties, one of them is that when taken in blocks of n consecutive positions they form 2ⁿ-1 different codes in a closed circular sequence. This property can be used for measuring absolute angular positions as the circle can be divided in as many parts as different codes can be retrieved. This paper describes how can a closed binary sequence with arbitrary length be effectively designed with the...



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Approximating subtree distances between Phylogenies

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Bonet Carbonell, Maria Luisa, St. John, Katherine, Mahindru, Ruchi, Amenta, Nina

We give a 5-approximation algorithm to the rooted Subtree-Prune-and-Regraft (rSPR) distance between two phylogenies, which was recently shown to be NP-complete by Bordewich and Semple [5]. This paper presents the first approximation result for this important tree distance. The algorithm follows a standard format for tree distances such as Rodrigues et al. [24] and Hein et al. [13]. The novel ideas are in the analysis. In the analysis, the cost of the algorithm uses a \cascading" scheme...



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Generalized backward doubly stochastic differential equations and SPDEs with nonlinear Neumann boundary conditions

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Boufoussi, Brahim, Van Casteren, Jan, Mrhardy, Naoual

In this paper, a new class of generalized backward doubly stochastic differential equations is investigated. This class involves an integral with respect to an adapted continuous increasing process. A probabilistic representation for viscosity solutions of semi-linear stochastic partial differential equations with a Neumann boundary condition is given.



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Quasi-Potency and Cyclic subgroup separability

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Burillo Puig, Josep, Martino, Armando

We study the profinite topology on discrete groups and in particular the property of cyclic subgroup separability. We investigate the class of quasi-potent, cyclic subgroup separable groups, producing many examples and showing how it behaves with respect to certain group constructions.



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Distortion of wreath products in some finitely presented groups

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Cleary, Sean

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Infinite index subgroups and finiteness properties of intersections of geometrically finite groups

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Apanasov, Boris N.

We explore which types of finiteness properties are possible for intersections of geometrically finite groups of isometries in negatively curved symmetric rank one spaces. Our main tool is a twist construction which takes as input a geometrically finite group containing a normal subgroup of infinite index with given finiteness properties and infinite Abelian quotient, and produces a pair of geometrically finite groups whose intersection is isomorphic to the normal subgroup.



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Weak systems of Gandy, Jensen and Devlin

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Mathias, A.R.D.

In Part I, we formulate and examine some systems that have arisen in the study of the constructible hierarchy; we find numerous transitive models for them, among which are supertransitive models containing all ordinals that show that Devlin's system BS lies strictly between Gandy's systems PZ and BST'; and we use our models to show that BS fails to handle even the simplest rudimentary functions, and is thus inadequate for the use intended for it in Devlin's treatise. In Part...



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On moduli of smoothness of fractional order

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Tikhonov, Sergey Yu.

In this paper we consider the properties of moduli of smoothness of fractional order. The main result of the paper describes the equivalence of the modulus of smoothness and a function from some class.



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Cat(0) and Cat (-1) dimensions of torsion free

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Brady, Noel, Crisp, John

We show that a particular free-by-cyclic group has CAT(0) dimension equal to 2, but CAT(-1) dimension equal to 3. We also classify the minimal proper 2-dimensional CAT(0) actions of this group; they correspond, up to scaling, to a 1-parameter family of locally CAT(0) piecewise Euclidean metrics on a fixed presentation complex for the group. This information is used to produce an infinite family of 2-dimensional hyperbolic groups, which do not act properly by isometries on any proper CAT(0)...



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On Boas-Type Problem

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Tikhonov, Sergey Yu.

R.P. Boas has found necessary and sufficient conditions of belonging of function to Lipschitz class. From his findings it turned out, that the conditions on sine and cosine coefficients for belonging of function to Lip α(0 & α & 1) are the same, but for Lip 1 are different. Later his results were generalized by many authors in the viewpoint of generalization of condition on the majorant of modulus of continuity. The aim of this paper is to obtain Boas-type theorems for generalized...



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Reduction, Linearization and stability of relative equilibria for mechanical systems on riemannian manifolds

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Bullo, Francesco, Lewis, Andrew D.

Consider a Riemannian manifold equipped with an infinitesimal isometry. For this setup, a unified treatment is provided, solely in the language of Riemannian geometry, of techniques in reduction, linearization, and stability of relative equilibria. In particular, for mechanical control systems, an explicit characterization is given for the manner in which reduction by an infinitesimal isometry, and linearization along a controlled trajectory "commute." As part of the development,...



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Shellability of noncrossing partition lattices

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Athanasiadis, Christos A., Brady, Thomas, Watt, Colum

We give a case-free proof that the lattice of noncrossing partitions associated to any finite real reflection group is EL-shellable. Shellability of these lattices was open for the groups of type Dn and those of exceptional type and rank at least three.



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Minimal truncations of supersingular p-divisible groups

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Nicole, Marc-Hubert, Vasiu, Adrian

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Lower bounds for the number of limit cycles of trigonometric Abel equations

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Álvarez Torres, María Jesús, Gasull i Embid, Armengol, Yu, Jiang

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Artículo científico antes de ser publicado, versión del autor (preprint)

Refilling meridians in a genus 2 handlebody complement

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Scharlemann, Martin

Suppose a genus two handlebody is removed from a 3-manifold M and then a single meridian of the handlebody is restored. The result is a knot or link complement in M and it is natural to ask whether geometric properties of the link complement say something about the meridian that was restored. Here we consider what the relation must be between two not necessarily disjoint meridians so that restoring each of them gives a trivial knot or a split link.



Artículo científico antes de ser publicado, versión del autor (preprint)

Intersection Pairing and intersection motive of surfaces

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Wildeshaus, Jörg

We construct the Chow motive modelling intersection co-homology of a proper surface. We then study its functoriality properties. Using Murre's decompositions of the motive of a desingularization into KÄunneth components [Mr1], we show that such decompositions exist also for the intersection motive.



Artículo científico antes de ser publicado, versión del autor (preprint)

Limit Cycles for a class of three dimensional polynomial differential systems

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Llibre i Saló, Jaume, Yu, Jiang

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On the upper bound of the number of limit cycles obtained by the second order averaging method II

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Llibre i Saló, Jaume, Yu, Jiang

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Artículo científico antes de ser publicado, versión del autor (preprint)

On the upper bound of the number of limit cycles obtained by the second order averaging method I

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Llibre i Saló, Jaume, Yu, Jiang

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Artículo científico antes de ser publicado, versión del autor (preprint)

Limit cycles for cubic systems with a symmetry of order 4 and without in nite critical points

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Álvarez Torres, María Jesús, Gasull i Embid, Armengol, Prohens i Sastre, Rafel, J.

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Inverse Problems for multiple invariant curves

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Cristopher, Colin, Llibre i Saló, Jaume, Pantazi, Chara, Walcher, Sebastian

Planar polynomial vector fields which admit invariant algebraic curves, Darboux integrating factors or Darboux first integrals are of special interest. In the present paper we solve the inverse problem for invariant algebraic curves with a given multiplicity and for integrating factors, under generic assumptions regarding the (multiple) invariant algebraic curves involved. In particular we prove, in this generic scenario, that the existence of a Darboux integrating factor implies Darboux...



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Geometric tools to determine the hyperbolicity of limit cycles

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Guillamon i Grabolosa, Antoni, Sabatini, Marco

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Algebraic extensions in free groups

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Myasnikov, Alexei, Ventura, Enric, Weil, Pascal

The aim of this paper is to unify the points of view of three recent and independent papers (Ventura 1997, Margolis, Sapir and Weil 2001 and Kapovich and Miasnikov 2002), where similar modern versions of a 1951 theorem of Takahasi were given. We develop a theory of algebraic extensions for free groups, highlighting the analogies and differences with respect to the corresponding classical fieldt heoretic notions, and we discuss in detail the notion of algebraic closure. We apply that theory to...



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Lp-solutions to BSDEs with super-linear growth coefficient. Application to degenerate semilinear PDEs.

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Bahlali, K., Essaky, E.H., Hassani, M., Pardoux, E.

We consider multidimensional backward stochastic differential equations (BSDEs). We prove the existence and uniqueness of solutions when the coefficient grow super-linearly, and moreover, can be neither locally Lipschitz in the variable y nor in the variable z. This is done with super-linear growth coefficient and a p-integrable terminal condition (p & 1). As application, we establish the existence and uniqueness of solutions to degenerate semilinear PDEs with superlinear growth generator...



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Reflected Backward Stochastic Differential Equation with Jumps and RCLL Obstacle

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Essaky, E.H.

In this paper we study one-dimensional reflected backward stochastic differential equation when the noise is driven by a Brownian motion and an independent Poisson point process when the solution is forced to stay above a right continuous left-hand limited obstacle. We prove existence and uniqueness of the solution by using a penalization method combined with a monotonic limit theorem.



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Normal forms for rational difference equations with applications to the global periodicity problem

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Mañosa, Víctor, Rubió Massegú, Josep

We propose a classification and derive the associated normal forms for rational difference equations with complex coefficients. As an application, we study the global periodicity problem for second order rational difference equations with complex coefficients. We find new necessary conditions as well as some new examples of globally periodic equations.



Artículo científico antes de ser publicado, versión del autor (preprint)

The density of injective endomorphisms of a free group

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Martino, Armando, Turner, Edward C., Ventura, Enric

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Periodic orbits in complex Abel equation

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Cima, Anna, Gasull i Embid, Armengol, Mañosas Capellades, Francesc

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Restricted walks in regular trees

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Ciobanu, Laura, Radomirovic, S.

Let T be the Cayley graph of a finitely generated free group F. Given two vertices in T consider all the walks of a given length between these vertices that at a certain time must follow a number of predetermined steps. We give formulas for the number of such walks by expressing the problem in terms of equations in F and solving the corresponding equations.



Artículo científico antes de ser publicado, versión del autor (preprint)

The third order Melnikov function of a quadratic center under quadratic perturbation

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Buica, A., Gasull i Embid, Armengol

We study quadratic perturbations of the integrable system (1+x)dH; where H =(x²+y²)=2: We prove that the first three Melnikov functions associated to the perturbed system give rise at most to three limit cycles.



Artículo científico antes de ser publicado, versión del autor (preprint)

Asymptotics of orthogonal polynomials via the Koosis theorem

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Nazarov, F., Volberg, A., Yuditskii, P.

The main aim of this short paper is to advertize the Koosis theorem in the mathematical community, especially among those who study orthogonal polynomials. We (try to) do this by proving a new theorem about asymptotics of orthogonal polynomi- als for which the Koosis theorem seems to be the most natural tool. Namely, we consider the case when a SzegÄo measure on the unit circumference is perturbed by an arbitrary measure inside the unit disk and an arbitrary Blaschke sequence of point masses...



Artículo científico antes de ser publicado, versión del autor (preprint)

A rotation method which gives linear Lp-Estimates for powers of the Ahlfors-Beurling operator

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Dragicevic, O., Petermichl, S., Volberg, A.

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Quadratic perturbations of a quadratic reversible Lotka-Volterra System

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Li, Chengzhi, Llibre i Saló, Jaume

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Non compact euclidean cone 3-manifolds with cone angles less than 2∏

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Cooper, D., Porti Piqué, Joan

We study of noncompact Euclidean cone manifolds with cone angles less than c&2π and singular locus a submanifold. More precisely, we describe its structure outside a compact set. As a corol lary we classify those with cone angles & 2π/3 and those with cone angles = 2π/3.



Artículo científico antes de ser publicado, versión del autor (preprint)

Hopf bifurcation of a delay differential equation with two delays

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Llibre i Saló, Jaume, Tarta, A.

We consider a delay differential equation with two delays. The Hopf bifurcation of this equation is investigated together with the stability of the bifurcated periodic solution, its period and the bifurcation direction. Finally, three applications are given.



Artículo científico antes de ser publicado, versión del autor (preprint)

The mean dehn functions of Abelian groups

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Bogopolski, O., Ventura, Enric

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Traverso's isogeny conjecture for p-divisible groups

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Nicole, Marc-Hubert, Vasiu, Adrian

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Artículo científico antes de ser publicado, versión del autor (preprint)

Lipschitz harmonic capacity and Bilipschitz images of cantor sets

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Garnett, John B., Prat Baiget, Laura, Tolsa Domènech, Xavier

For bilipschitz images of Cantor sets in Rd we estimate the Lipschitz harmonic capacity and show this capacity is invariant under bilipschitz homeomorphisms.



Artículo científico antes de ser publicado, versión del autor (preprint)

Two algorithms to find a power integral basis

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
El Fadil, L.

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Artículo científico antes de ser publicado, versión del autor (preprint)

Galois extension of CP-Graded ring extensions

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
El Fadil, L.

In this paper, we investigate galois theory of CP-graded ring extensions. In particular, we generalize some galois results given in [1, 2] and, without restriction to nor graded fields nor torsion free of the grade groups, we show that some results of graded field extensions given in [3] hold.



Artículo científico antes de ser publicado, versión del autor (preprint)

Valuations, intersections et fonctions de Belyi

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Litcanu, R.

We present in this article several possibilities to approach the height of an algebraic curve defined over a number field : as an intersection number via the Arakelov theory, as a limit point of the heights of its algebraic points and, finally, using the minimal degree of Belyi functions.



Artículo científico antes de ser publicado, versión del autor (preprint)

Petits points et conjecture de Bogomolov

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Litcanu, R.

This paper is devoted to the statement known as the Bogomolov conjecture on small points. We present the outline of Zhang’s proof of the generalized version of the conjecture. An explicit bound for the height of a non-torsion variety of an abelian variety is obtained in the frame of Arakelov theory. Some further developments are mentioned.



Artículo científico antes de ser publicado, versión del autor (preprint)

Semigroups of matrices of intermediate growth

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Cedó i Giné, Ferran, Okniski, Jan

Finitely generated linear semigroups over a field K that have intermediate growth are considered. New classes of such semigroups are found and a conjecture on the equivalence of the subexponential growth of a finitely generated linear semigroup S and the nonexistence of free noncommutative subsemigroups in S, or equivalently the existence of a nontrivial identity satisfied in S, is stated. This ‘growth alternative’ conjecture is proved for linear semigroups of degree 2, 3 or 4. Certain results...



Artículo científico antes de ser publicado, versión del autor (preprint)

Polynomial and linearized normal forms for almost periodic differential systems

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Li, W., Llibre i Saló, Jaume, Wu, H.

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Artículo científico antes de ser publicado, versión del autor (preprint)

Hopf bifurcation for degenerate singular points of multiplicity 2n-1 in dimension 3

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Llibre i Saló, Jaume, Wu, H.

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Artículo científico antes de ser publicado, versión del autor (preprint)

Reduction of periodic difference systems to linear or autonomous ones

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Li, W., Llibre i Saló, Jaume, Wu, H.

We extend Floquet theory for reducing nonlinear periodic difference systems to autonomous ones (actually linear) by using normal form theory.



Artículo científico antes de ser publicado, versión del autor (preprint)

Classes of measures generated by capacities

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Dafni, G.E., Karadzhov, J., Xiao, J.

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Artículo científico antes de ser publicado, versión del autor (preprint)

Large deviation for BSDE with subdifferential operator

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Essaky, E.H.

In this paper we prove that the solution of a backward stochastic differential equation, which involves a subdifferential operator and associated to a family of reflecting diffusion processes, converges to the solution of a deterministic backward equation and satisfes a large deviation principle.



Artículo científico antes de ser publicado, versión del autor (preprint)

On the injectivity of the Kudla-Millson lift and surjectivity of the Borcherds lift

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Bruinier, Jan H., Funke, J.

We consider the Kudla-Millson lift from elliptic modular forms of weight (p+q)/2 to closed q-forms on locally symmetric spaces corresponding to the orthogonal group O(p,q). We study the L²-norm of the lift following the Rallis inner product formula. We compute the contribution at the Archimedian place. For locally symmetric spaces associated to even unimodular lattices, we obtain an explicit formula for the L²-norm of the lift, which often implies that the lift is injective. For O(p,2) we...



Artículo científico antes de ser publicado, versión del autor (preprint)

CM points and weight 3=2 modular forms

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Funke, J.

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Stable rank of leavitt path algebra

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Pardo, E., Ara i Bertrán, Pere

We characterize the values of the stable rank for Leavitt path algebras, by giving concrete criteria in terms of properties of the underlying graph.



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The Cuntz semigroup, the Elliott conjecture, and dimension functions on C*-Algebras

Repositorio: Recercat. Dipósit de la Recerca de Catalunya
Brown, Nathanial P., Toms, Andrew S., Perera Domènech, Francesc

We prove that the Cuntz semigroup is recovered functorially from the Elliott invariant for a large class of C¤-algebras. In particular, our results apply to the largest class of simple C¤-algebras for which K-theoretic classification can be hoped for. This work has three significant consequences. First, it provides new conceptual insight into Elliott's classification program, proving that the usual form of the Elliott conjecture is equivalent, among Z-stable algebras, to a conjecture which...



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