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Results for "Matteo Beccari"

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Strong and weak divergence of exponential and linear-implicit Euler approximations for stochastic partial differential equations with superlinearly growing nonlinearitiesMar 14 2019The explicit Euler scheme and similar explicit approximation schemes (such as the Milstein scheme) are known to diverge strongly and numerically weakly in the case of one-dimensional stochastic ordinary differential equations with superlinearly growing ... More
A practical criterion for the existence of optimal piecewise Chebyshevian spline basesJan 04 2016A piecewise Chebyshevian spline space is a space of spline functions having pieces in different Extended Chebyshev spaces and where the continuity conditions between adjacent spline segments are expressed by means of connection matrices. Any such space ... More
On multi-degree splinesSep 14 2017Multi-degree splines are piecewise polynomial functions having sections of different degrees. For these splines, we discuss the construction of a B-spline basis by means of integral recurrence relations, extending the class of multi-degree splines that ... More
Piecewise Extended Chebyshev Spaces: a numerical test for designJun 24 2016Given a number of Extended Chebyshev (EC) spaces on adjacent intervals, all of the same dimension, we join them via convenient connection matrices without increasing the dimension. The global space is called a Piecewise Extended Chebyshev (PEC) Space. ... More
Clustering dynamics in a class of normalised generalised gamma dependent priorsAug 02 2016Nov 04 2016Normalised generalised gamma processes are random probability measures that induce nonparametric prior distributions widely used in Bayesian statistics, particularly for mixture modelling. We construct a class of dependent normalised generalised gamma ... More
Clustering dynamics in a class of normalised generalised gamma dependent priorsAug 02 2016Normalised generalised gamma processes are random probability measures that induce nonparametric prior distributions widely used in Bayesian statistics, particularly for mixture modelling. We construct a class of dependent normalised generalised gamma ... More
Star Formation in the Starburst Cluster in NGC 3603Mar 30 2012We have used new, deep, visible and near infrared observations of the compact starburst cluster in the giant HII region NGC 3603 and its surroundings with the WFC3 on HST and HAWK-I on the VLT to study in detail the physical properties of its intermediate ... More
Some insights on bicategories of fractions: representations and compositions of 2-morphismsOct 15 2014Apr 20 2016In this paper we investigate the construction of bicategories of fractions originally described by D. Pronk: given any bicategory $\mathcal{C}$ together with a suitable class of morphisms $\mathbf{W}$, one can construct a bicategory $\mathcal{C}[\mathbf{W}^{-1}]$, ... More
Chemically-exfoliated single-layer MoS$_2$ : stability, lattice dynamics and catalytic adsorption from first principlesDec 05 2013Chemically and mechanically exfoliated MoS$_2$ single-layer samples have substantially different properties. While mechanically exfoliated single-layers are mono-phase (1H polytype with Mo in trigonal prismatic coordination), the chemically exfoliated ... More
Cosmology with the lyman-alpha forest in the WMAP eraOct 15 2003In the WMAP era of high precision cosmology an accurate determination of the matter power spectrum from lyman-alpha forest data becomes crucial. When combining the matter power spectrum derived from CMB experiments with that inferred from lyman-alpha ... More
The coherent interaction between matter and radiation - A tutorial on the Jaynes-Cummings modelNov 04 2011The Jaynes-Cummings (JC) model is a milestone in the theory of coherent interaction between a two-level system and a single bosonic field mode. This tutorial aims to give a complete description of the model, analyzing the Hamiltonian of the system, its ... More
On the strong coupling expansion in the su(1|1) sector of N=4 SYMMay 08 2008May 12 2008We consider the anomalous dimension of the fermionic highest states Tr(psi^L) in the su(1|1) sector of N=4 SYM at strong coupling. In the thermodynamical L->OO limit it is described by a BES-like integral equation recently proposed by Rej, Staudacher ... More
Universality of three gaugino anomalous dimensions in N=4 SYMMay 04 2007May 05 2007We study maximal helicity three gaugino operators in N=4 Super Yang-Mills theory. We show that the lowest anomalous dimension of scaling operators with generic finite spin can be expressed in terms of the universal anomalous dimension appearing at twist-2. ... More
Anomalous dimensions at twist-3 in the sl(2) sector of N=4 SYMApr 26 2007We consider twist-3 operators in the sl(2) sector of N=4 SYM built out of three scalar fields with derivatives. We extract from the Bethe Ansatz equations of this sector the exact lowest anomalous dimension gamma(s) of scaling fields for several values ... More
Wave functions for Hamiltonian Lattice Gauge TheoryMar 21 2000We study four dimensional SU(2) lattice gauge theory in the Hamiltonian formalism by Green's Function Monte Carlo methods. A trial ground state wave function is introduced to improve the configuration sampling and we discuss the interplay between its ... More
Verification of Reachability Problems for Time Basic Petri NetsSep 09 2014Time-Basic Petri nets, is a powerful formalism for model- ing real-time systems where time constraints are expressed through time functions of marking's time description associated with transition, representing possible firing times. We introduce a technique ... More
Ultraluminous X-ray sources: three exciting yearsOct 19 2015The extreme extragalactic sources known as Ultraluminous X-ray Sources (ULX) represent a unique testing environment for compact objects population studies and the accretion process. Their nature has long been disputed. Their luminosity, well above the ... More
On the classification of complete area-stationary and stable surfaces in the sub-Riemannian Sol manifoldMay 25 2013Aug 17 2013We study the classification of area-stationary and stable $C^2$ regular surfaces in the space of the rigid motions of the Minkowski plane E(1,1), equipped with its sub-Riemannian structure. We construct examples of area-stationary surfaces that are not ... More
Hadronic Production of Heavy QuarksOct 29 1997We review the status of theoretical evaluations of heavy quark and heavy quarkonium hadroproduction cross sections and their comparisons with experimental data.
Jet Areas, and What They are Good ForJun 19 2007We introduce the concept of the area of a jet, and show how it can be used to perform the subtraction of even a large amount of diffuse noise from hard jets.
pQCD Calculations of Heavy Quark and J/psi ProductionFeb 20 2007We review the present status of theoretical predictions for both closed (J/psi) and open heavy quark production in high energy collisions, and their comparisons to experimental data.
QCD Predictions for Charm and Bottom Production at RHICDec 20 2005We present up-to-date QCD predictions for open charm and bottom production at RHIC in nucleon-nucleon collisions at \sqrt{S} = 200 GeV. The electron spectrum resulting from heavy flavor decays is also evaluated for direct comparison to the PHENIX and ... More
Rise and Fall of the Bottom Quark Production ExcessJul 16 2004We review the history of comparisons between bottom production measurements and QCD predictions. We challenge the existence of a `significant discrepancy', and argue that standard approaches to QCD calculations do a good job in describing the experimental ... More
An equilibrated fluxes approach to the Certified Descent Algorithm for shape optimization using conforming Finite Element and Discontinuous Galerkin discretizationsNov 10 2016The Certified Descent Algorithm (CDA) is a gradient-based method for shape optimization which certifies that the direction computed using the shape gradient is a genuine descent direction for the objective functional under analysis. It relies on the computation ... More
Contracting rigid germs in higher dimensionsSep 30 2011Jan 09 2013Following Favre, we define a holomorphic germ f:(C^d,0) -> (C^d,0) to be rigid if the union of the critical set of all iterates has simple normal crossing singularities. We give a partial classification of contracting rigid germs in arbitrary dimensions ... More
A Poincaré-Dulac renormalization theorem for attracting rigid germs in $\mathbb{C}^d$Mar 14 2011Sep 30 2011Studying the dynamics of attracting rigid germs $f:(\mathbb{C}^d, 0) \rightarrow (\mathbb{C}^d, 0)$ in dimension $d \geq 3$, a new phenomenon arise: principal resonances. The resonances of the classic Poincar\'e-Dulac theory are given by (multiplicative) ... More
Gravity, holography and applications to condensed matterOct 09 2016Oct 17 2016Momentum relaxation is an ever-present and unavoidable ingredient of any realistic condensed matter system. In real-world materials the presence of a lattice, impurities or disorder forces momentum to dissipate and leads to relevant physical effects such ... More
Lyapunov exponents, holomorphic flat bundles and de Rham moduli spaceOct 30 2018We consider Lyapunov exponents for flat bundles over hyperbolic curves defined via parallel transport over the geodesic flow. We refine a lower bound obtained by Eskin, Kontsevich, Moeller and Zorich showing that the sum of the first k exponents is greater ... More
Stress-corrosion mechanisms in silicate glassesJan 19 2009Apr 01 2009The present review is intended to revisit the advances and debates in the comprehension of the mechanisms of subcritical crack propagation in silicate glasses almost a century after its initial developments. Glass has inspired the initial insights of ... More
Radial and cylindrical symmetry of solutions to the Cahn-Hilliard equationFeb 01 2019The paper is devoted to the classification of entire solutions to the Cahn-Hilliard equation $-\Delta u = u-u^3-\delta$ in $\R^N$, with particular interest in those solutions whose nodal set is either bounded or contained in a cylinder. The aim is to ... More
Combinatorially two-orbit convex polytopesNov 06 2014Feb 19 2015Any convex polytope whose combinatorial automorphism group has two orbits on the flags is isomorphic to one whose group of Euclidean symmetries has two orbits on the flags (equivalently, to one whose automorphism group and symmetry group coincide.) Hence, ... More
A temporal semantics for Nilpotent Minimum logicOct 22 2013In [Ban97] a connection among rough sets (in particular, pre-rough algebras) and three-valued {\L}ukasiewicz logic {\L}3 is pointed out. In this paper we present a temporal like semantics for Nilpotent Minimum logic NM ([Fod95, EG01]), in which the logic ... More
The classification of isotrivially fibred surfaces with p_g=q=2Apr 08 2009Jul 29 2010An isotrivially fibred surface is a smooth projective surface endowed with a morphism onto a curve such that all the smooth fibres are isomorphic to each other. The first goal of this paper is to classify the isotrivially fibred surfaces with $p_g=q=2$ ... More
Interior regularity of solutions of non-local equations in Sobolev and Nikol'skii spacesJan 12 2016We prove interior $H^{2s-\varepsilon}$ regularity for weak solutions of linear elliptic integro-differential equations close to the fractional $s$-Laplacian. The result is obtained via intermediate estimates in Nikol'skii spaces, which are in turn carried ... More
Localisation in 2+1 dimensional SU(3) pure gauge theory at finite temperatureMar 12 2019I study the localisation properties of low Dirac eigenmodes in 2+1 dimensional SU(3) pure gauge theory, both in the low-temperature, confined and chirally-broken phase and in the high-temperature, deconfined and chirally-restored phase, by means of numerical ... More
A Law of Large Numbers for an Interacting Particle System with Confining PotentialJan 03 2007In this paper we consider an interacting particle system modeled as a system of $N$ stochastic differential equations driven by Brownian motions with a drift term including a confining potential acting on each particle, and an interaction potential modeling ... More
A bicategory of reduced orbifolds from the point of view of differential geometry - IApr 25 2013Jan 09 2015We describe a bicategory $(\mathcal{R}ed\,\mathcal{O}rb)$ of reduced orbifolds in the framework of classical differential geometry (i.e. without any explicit reference to notions of Lie groupoids or differentiable stacks, but only using orbifold atlases, ... More
Finite generation of iterated wreath products in product actionMay 30 2015Jun 21 2015Let $\mathcal{S}$ be a sequence of finite perfect transitive permutation groups with uniformly bounded number of generators. We prove that the infinitely iterated wreath product in product action of the groups in $\mathcal{S}$ is topologically finitely ... More
A blackbody is not a blackboxOct 27 2010Nov 08 2010We discuss carefully the blackbody approximation, stressing what it is (a limit case of radiative transfer), and what it is not (the assumption that the body is perfectly absorbing, i.e. black). Furthermore, we derive the Planck spectrum without enclosing ... More
Some insights on bicategories of fractions - IIIOct 23 2014Nov 21 2014We fix any bicategory $\mathscr{A}$ together with a class of morphisms $\mathbf{W}_{\mathscr{A}}$, such that there is a bicategory of fractions $\mathscr{A}[\mathbf{W}_{\mathscr{A}}^{-1}]$. Given another such pair $(\mathscr{B},\mathbf{W}_{\mathscr{B}})$ ... More
Can Market Risk Perception Drive Inefficient Prices? Theory and EvidenceSep 17 2014This work presents an asset pricing model that under rational expectation equilibrium perspective shows how, depending on risk aversion and noise volatility, a risky-asset has one equilibrium price that differs in term of efficiency: an informational ... More
On the classification of surfaces of general type with $p_g=q=2$Nov 22 2013The paper is an extended version of the talk which I gave at the XIX Congresso dell'UMI in Bologna in September 2011. The aim of this paper is twofold: first, to give an overview on the recent development in the classification of surfaces of general type ... More
Dissecting financial markets: Sectors and statesJul 05 2002By analyzing a large data set of daily returns with data clustering technique, we identify economic sectors as clusters of assets with a similar economic dynamics. The sector size distribution follows Zipf's law. Secondly, we find that patterns of daily ... More
Recent Progress in Jet Algorithms and Their Impact in Underlying Event StudiesJun 09 2009Recent developments in jet clustering are reviewed. We present a list of fast and infrared and collinear safe algorithms, and also describe new tools like jet areas. We show how these techniques can be applied to the study of underlying event or, more ... More
The LEP Trail to Non-Perturbative QCDJul 03 2001This talk summarizes the presentations given in the Hadronic Physics session at the LEPTRE meeting, emphasizing the importance of LEP data in our quest for a successful approach to non-perturbative QCD.
Heavy quarks, from discovery to precisionSep 07 2011The discoveries of the heavy quarks are briefly reviewed, with a focus on the role played by Mario Greco in the interpretation of the experimental observations, and on his contributions to heavy quark precision phenomenology.
Perturbative and Non-Perturbative Issues in Heavy Quark FragmentationMay 29 2002We review the state-of-the-art of our understanding of heavy quark fragmentation. Recent e^+e^- data for B mesons are compared to the most up-to-date theoretical predictions, and the need for inclusion of a non-perturbative component is discussed. Experimental ... More
Phenomenology of ``Onium'' ProductionMay 18 1995The phenomenology of heavy quarkonia production in hadron collisions is reviewed. The theoretical predictions are compared to data. Commonly used production models are shown to fail in explaining all the experimental findings. The shortcomings of these ... More
On the Arithmetical Rank of Certain Segre EmbeddingsJul 30 2010We study the number of (set-theoretically) defining equations of Segre products of projective spaces times certain projective hypersurfaces, extending results by Singh and Walther. Meanwhile, we prove some results about the cohomological dimension of ... More
Category forcings, $MM^{+++}$, and generic absoluteness for the theory of strong forcing axiomsMay 09 2013Jul 29 2015We introduce a category whose objects are stationary set preserving complete boolean algebras and whose arrows are complete homomorphisms with a stationary set preserving quotient. We show that the cut of this category at a rank initial segment of the ... More
Wilson-loop formalism for Reggeon exchange in soft high-energy scatteringApr 17 2012Dec 06 2012We derive a nonperturbative expression for the non-vacuum, qqbar-Reggeon-exchange contribution to the meson-meson elastic scattering amplitude at high energy and low momentum transfer, in the framework of QCD. Describing the mesons in terms of colourless ... More
Renormalisation of gauge theories on general anisotropic lattices and high-energy scattering in QCDJun 15 2015Aug 27 2015We study the renormalisation of $SU(N_c)$ gauge theories on general anisotropic lattices, to one-loop order in perturbation theory, employing the background field method. The results are then applied in the context of two different approaches to hadronic ... More
High-energy bounds on total cross sections in N=4 SYM from AdS/CFTSep 15 2010Using the AdS/CFT correspondence, we study the high-energy behavior of scattering amplitudes in N=4 SYM gauge theory for dipole-dipole soft elastic scattering, described in the Wilson-loop correlator formalism. The amplitudes are evaluated in the dual ... More
Differential measurements of $t \overline{t}$ production in ATLASJan 15 2019Differential cross sections of $t \overline{t}$ production have been measured by the ATLAS experiment at the LHC. Monte Carlo calculations provide an overall good modeling of all measured distributions, except for the transverse momentum of the top quark, ... More
On some logical and algebraic properties of axiomatic extensions of the monoidal t-norm based logic MTL related with single chain completenessMay 21 2012In [Mon11] are studied, for the axiomatic extensions of the monoidal t-norm based logic ([EG01]), the properties of single chain completeness. On the other side, in [GJKO07, Chapter 5] are studied many logical and algebraic properties (like Halld\'en ... More
Preconditioned fully implicit PDE solvers for monument conservationFeb 07 2010Mathematical models for the description, in a quantitative way, of the damages induced on the monuments by the action of specific pollutants are often systems of nonlinear, possibly degenerate, parabolic equations. Although some the asymptotic properties ... More
Cohomological and Combinatorial Methods in the Study of Symbolic Powers and Equations defining VarietiesMay 27 2011In this PhD thesis we will discuss some aspects in Commutative Algebra which have interactions with Algebraic Geometry, Representation Theory and Combinatorics. In particular, in the first chapter we will focus on understanding when certain cohomology ... More
Aperiodic fractional obstacle problemsSep 28 2009We determine the asymptotic behaviour of (bilateral) obstacle problems for fractional energies in rather general aperiodic settings via Gamma-convergence arguments. As further developments we consider obstacles with random sizes and shapes located on ... More
Connectivity of hyperplane sections of domainsFeb 26 2018Feb 28 2018During the conference held in 2017 in Minneapolis for his 60th birthday, Gennady Lyubeznik proposed the following problem: Find a complete local domain and an element in it having three minimal primes such that the sum of any two of them has height 2 ... More
On deformations of multidimensional Poisson brackets of hydrodynamic typeDec 06 2013Nov 28 2014The theory of Poisson Vertex Algebras (PVAs) is a good framework to treat Hamiltonian partial differential equations. A PVA consists of a pair $(\mathcal{A},\{\cdot_\lambda\cdot\})$ of a differential algebra $\mathcal{A}$ and a bilinear operation called ... More
Technical notes: Syntax-aware Representation Learning With Pointer NetworksMar 17 2019This is a work-in-progress report, which aims to share preliminary results of a novel sequence-to-sequence schema for dependency parsing that relies on a combination of a BiLSTM and two Pointer Networks (Vinyals et al., 2015), in which the final softmax ... More
Optimal price management in retail energy markets: an impulse control problem with asymptotic estimatesMar 21 2018Aug 30 2018We consider a retailer who buys energy in the wholesale market and resells it to final consumers. The retailer has to decide when to intervene to change the price he asks to his customers, in order to maximize his income. We model the problem as an infinite-horizon ... More
Viral Search algorithmJun 14 2016The article, after a brief introduction on genetic algorithms and their functioning, presents a kind of genetic algorithm called Viral Search. We present the key concepts, we formally derive the algorithm and we perform numerical tests designed to illustrate ... More
On the irrationality of certain coefficients of the Alekseev-Torossian associatorMar 23 2016We give explicit formulas for the first few coefficients of the Alekseev-Torossian associator and a second Drinfeld associator. This is done by analyzing the free and transitive action of the Grothendieck-Teichm\"uller group and its Lie algebra $\mathfrak{grt}_1$ ... More
Some insights on bicategories of fractions - IIOct 19 2014Nov 21 2014We fix any bicategory $\mathscr{A}$ together with a class of morphisms $\mathbf{W}_{\mathscr{A}}$, such that there is a bicategory of fractions $\mathscr{A}[\mathbf{W}_{\mathscr{A}}^{-1}]$. Given another such pair $(\mathscr{B},\mathbf{W}_{\mathscr{B}})$ ... More
Computability of Følner setsJun 14 2016We define the notion of computability of F\o lner sets for finitely generated amenable groups. We prove, by an explicit description, that the Kharlampovich group, a finitely presented solvable group with unsolvable word problem, has computable F\o lner ... More
Constructing Coverability Graphs for Time Basic Petri NetsSep 19 2014Time-Basic Petri nets, is a powerful formalism for modeling real-time systems where time constraints are expressed through time functions of marking's time description associated with transition, representing possible firing times. We introduce a technique ... More
The Multiphase Buoyant Plume Solution of the Dusty Gas ModelJun 04 2015Sep 12 2015Starting from the balance equations of mass, momentum and energy we formulate an integral 1D model for a poly-disperse mixture injected in the atmosphere. We write all the equations, either in their most general formulation or in the more simplified, ... More
Exact cascading nonlinearity in quasi-phase-matched quadratic mediaFeb 27 2014The evolution of light pulses and beams in a quasi-phase-matched (QPM) quadratic medium is usually described by considering only the spatial harmonic of the QPM grating that minimizes the residual phase-mismatch. I show that, for strongly phase-mismatched ... More
Species dynamics in the two-parameter Poisson-Dirichlet diffusion modelMay 01 2013Apr 01 2014The recently introduced two-parameter infinitely-many neutral alleles model extends the celebrated one-parameter version, related to Kingman's distribution, to diffusive two-parameter Poisson-Dirichlet frequencies. Here we investigate the dynamics driving ... More
Nuclear effects and neutron structure in deeply virtual Compton scattering off 3HeApr 01 2014The study of nuclear generalized parton distributions (GPDs) could be a crucial achievement of hadronic physics since they open new ways to obtain new information on the structure of bound nucleons, in particular, to access the neutron GPDs. Here, the ... More
De-noising the galaxies in the Hubble XDF with EMPCAJul 19 2016We present a method to model optical images of galaxies using Expectation Maximization Principal Components Analysis (EMPCA). The method relies on the data alone and does not assume any pre-established model or fitting formula. It preserves the statistical ... More
Regularity results and Harnack inequalities for minimizers and solutions of nonlocal problems: a unified approach via fractional De Giorgi classesSep 29 2016We study energy functionals obtained by adding a possibly discontinuous potential to an interaction term modeled upon a Gagliardo-type fractional seminorm. We prove that minimizers of such non-differentiable functionals are locally bounded, H\"older continuous, ... More
Recent advances on inconsistency indices for pairwise comparisons - a commentaryMar 28 2015Mar 10 2016This paper recalls the definition of consistency for pairwise comparison matrices and briefly presents the concept of inconsistency index in connection to other aspects of the theory of pairwise comparisons. By commenting on a recent contribution by Koczkodaj ... More
Quantum Theory of particles and fields as an extension of a probabilistic variational approach to classical mechanics and classical field theory. IFeb 25 2009Jul 28 2009A theoretical scheme, based on a probabilistic generalization of the Hamilton's principle, is elaborated to obtain an unified description of more general dynamical behaviors determined both from a lagrangian function and by mechanisms not contemplated ... More
Algebra of Observables and States for Quantum Abelian DualityNov 28 2016The study of dualities is a central issue in several modern approaches to quantum field theory, as they have broad consequences on the structure and on the properties of the theory itself. We call Abelian duality the generalisation to arbitrary spacetime ... More
Classification of one-dimensional superattracting germs in positive characteristicApr 20 2013We give a classification of superattracting germs in dimension one over a complete normed algebraically closed field of positive characteristic up to conjugacy. In particular we show that formal and analytic classifications coincide for these germs. We ... More
Critical points of a perturbed Otha-Kawasaki functionalJan 26 2016In the paper, we consider a small perturbation of the Otha-Kawasaki functional and we construct at least four critical points close to suitable translations of the Schwarz P surface with fixed volume.
The variety generated by all the ordinal sums of perfect MV-chainsMar 30 2011Apr 04 2012We present the logic BL_Chang, an axiomatic extension of BL (see P. H\'ajek - Metamathematics of fuzzy logic - 1998, Kluwer) whose corresponding algebras form the smallest variety containing all the ordinal sums of perfect MV-chains. We will analyze this ... More
Symbolic Powers and MatroidsMar 15 2010Sep 16 2011We prove that all the symbolic powers of a Stanley-Reisner ideal are Cohen-Macaulay if and only if the associated simplicial complex is a matroid.
On generation problems in generalised Wilson type groupsDec 25 2014May 30 2015We study a family of hereditarily just infinite profinite groups obtained by iterated wreath products introduced by J. Wilson in 2010. We find explicit generators for this family in a number of cases using combinatorial methods. We then discuss determination ... More
Regularity results and Harnack inequalities for minimizers and solutions of nonlocal problems: a unified approach via fractional De Giorgi classesSep 29 2016Nov 21 2018We study energy functionals obtained by adding a possibly discontinuous potential to an interaction term modeled upon a Gagliardo-type fractional seminorm. We prove that minimizers of such non-differentiable functionals are locally bounded, H\"older continuous, ... More
Bayesian MIDAS Penalized Regressions: Estimation, Selection, and PredictionMar 19 2019We propose a new approach to mixed-frequency regressions in a high-dimensional environment that resorts to Group Lasso penalization and Bayesian techniques for estimation and inference. To improve the sparse recovery ability of the model, we also consider ... More
Cycle/cocycle oblique projections on oriented graphsMay 05 2014May 07 2014It is well known that the edge vector space of an oriented graph can be decomposed in terms of cycles and cocycles (alias cuts, or bonds), and that a basis for the cycle and the cocycle spaces can be generated by adding and removing edges to an arbitrarily ... More
Universal families of extensions of coherent systemsDec 01 2012We prove a result of cohomology and base change for families of coherent systems over a curve. We use that in order to prove the existence of (non-split, non-degenerate) universal families of extensions for families of coherent systems (in the spirit ... More
The Credibility Theory applied to backtesting Counterparty Credit RiskSep 17 2014Credibility theory provides tools to obtain better estimates by combining individual data with sample information. We apply the Credibility theory to a Uniform distribution that is used in testing the reliability of forecasting an interest rate for long ... More
A complete proof of coherence for symmetric monoidal categories using rewritingJun 06 2016A symmetric monoidal category is a category equipped with an associative and commutative (binary) product and an object which is the unit for the product. In fact, those properties only hold up to natural isomorphisms which satisfy some coherence conditions. ... More
Mean of Ratios or Ratio of Means: statistical uncertainty applied to estimate Multiperiod Probability of DefaulSep 17 2014The estimate of a Multiperiod probability of default applied to residential mortgages can be obtained using the mean of the observed default, so called the Mean of ratios estimator, or aggregating the default and the issued mortgages and computing the ... More
Thermodynamics of inequalities: from precariousness to economic stratificationJun 25 2014Nov 30 2014Growing economic inequalities are observed in several countries throughout the world. Following Pareto, the power-law structure of these inequalities has been the subject of much theoretical and empirical work. But their nonequilibrium dynamics, e.g. ... More
On the supersymmetric vacua of the Veneziano-Wosiek modelJan 24 2007We study the supersymmetric vacua of the Veneziano-Wosiek model in sectors with fermion number F=2, 4 at finite 't Hooft coupling lambda. We prove that for F=2 there are two zero energy vacua for lambda > lambda_c = 1 and none otherwise. We give the analytical ... More
Maximal Stability Regions for Superconducting Ground States of Generalized Hubbard ModelsApr 09 1999For a class of generalized Hubbard models, we determine the maximal stability region for the superconducting eta-pairing ground state. We exploit the Optimized Ground State (OGS) approach and the Lanczos diagonalization procedure to derive a sequence ... More
Bosonization and the lattice Gross-Neveu modelDec 06 1993We consider a lattice version of the bosonized Gross-Neveu model. It is explicitely chiral symmetric and its numerical simulation does not involve any anticommuting field. We study its non trivial $1/N$ expansion up to the next-to-leading term comparing ... More
Surfaces isogenous to a product of curves, braid groups and mapping class groupsNov 22 2013This article is a revised version of the talk I gave at the conference ``Beauville Surfaces and groups'' held in Newcastle in June 2012. It presents some group theoretical methods to give bounds on the number of connected components of the moduli space ... More
Spiraling toward market completeness and financial instabilityJun 08 2009I study the limit of a large random economy, where a set of consumers invests in financial instruments engineered by banks, in order to optimize their future consumption. This exercise shows that, even in the ideal case of perfect competition, where full ... More
First and second variation formulae for the sub-Riemannian area in three-dimensional pseudo-hermitian manifoldsSep 28 2011Oct 03 2011We calculate the first and the second variation formula for the sub-Riemannian area in three dimensional pseudo-hermitian manifolds. We consider general variations that can move the singular set of a C^2 surface and non-singular variation for C_H^2 surfaces. ... More
The regularity of Euclidean Lipschitz boundaries with prescribed mean curvature in three-dimensional contact sub-Riemannian manifoldsJul 26 2015Feb 09 2016In this paper we consider a set $E\subset\Omega$ with prescribed mean curvature $f\in C(\Omega)$ and Euclidean Lipschitz boundary $\partial E=\Sigma$ inside a three-dimensional contact sub-Riemannian manifold $M$. We prove that if $\Sigma$ is locally ... More
FastJet: a code for fast k_t clustering, and moreJul 06 2006Two main classes of jet clustering algorithms, cone and k_t, are briefly discussed. It is argued that the former can be often cumbersome to define and implement, and difficult to analyze in terms of its behaviour with respect to soft and collinear emissions. ... More
Soft-Gluon Resummation in Heavy Quarkonium PhysicsOct 20 1999Soft-gluon resummation within the framework of heavy quarkonium hadroproduction is considered. A few selected cases are studied in detail. A sizeable increase of the cross sections with respect to the next-to-leading order predictions with central factorization/renormalization ... More
Computational Interpretations of Markov's principleNov 11 2016Markov's principle is a statement that originated in the Russian school of Constructive Mathematics and stated originally that "if it is impossible that an algorithm does not terminate, then it will terminate". This principle has been adapted to many ... More
Wilson-loop formalism for Reggeon exchange at high energySep 26 2012I will discuss how the non-vacuum, quark-antiquark Reggeon-exchange contribution to meson-meson elastic scattering, at high energy and low tranferred momentum, can be related to the path-integral of a certain Wilson-loop expectation value over the trajectories ... More