@article {2023, title = {A general splitting principle on RCD spaces and applications to spaces with positive spectrum}, year = {2023}, abstract = {

In this paper we develop a general {\textquoteleft}analytic{\textquoteright} splitting principle for RCD spaces: we show that if there is a function with suitable Laplacian and Hessian, then the space is (isomorphic to) a warped product. Our result covers most of the splitting-like results currently available in the literature about RCD spaces. We then apply it to extend to the non-smooth category some structural property of Riemannian manifolds obtained by Li and Wang.

}, author = {Nicola Gigli and Fabio Marconi} } @article {2022, title = {A Gradient Flow Equation for Optimal Control Problems With End-point Cost}, year = {2022}, month = {2022/07/07}, abstract = {In this paper, we consider a control system of the form $\dot x = F(x)u$, linear in the control variable u. Given a fixed starting point, we study a finite-horizon optimal control problem, where we want to minimize a weighted sum of an end-point cost and the squared 2-norm of the control. This functional induces a gradient flow on the Hilbert space of admissible controls, and we prove a convergence result by means of the Lojasiewicz-Simon inequality. Finally, we show that, if we let the weight of the end-point cost tend to infinity, the resulting family of functionals is Γ-convergent, and it turns out that the limiting problem consists in joining the starting point and a minimizer of the end-point cost with a horizontal length-minimizer path.}, isbn = {1573-8698}, url = {https://doi.org/10.1007/s10883-022-09604-2}, author = {Alessandro Scagliotti} } @article {han2020gauge, title = {On the gauge group of Galois objects}, year = {2020}, month = {03/2020}, abstract = {We study the Ehresmann--Schauenburg bialgebroid of a noncommutative principal bundle as a quantization of the classical gauge groupoid of a principal bundle. When the base algebra is in the centre of the total space algebra, the gauge group of the noncommutative principal bundle is isomorphic to the group of bisections of the bialgebroid. In particular we consider Galois objects (non-trivial noncommutative bundles over a point in a sense) for which the bialgebroid is a Hopf algebra. For these we give a crossed module structure for the bisections and the automorphisms of the bialgebroid. Examples include Galois objects of group Hopf algebras and of Taft algebras.}, url = {https://arxiv.org/abs/2002.06097}, author = {Xiao Han and Giovanni Landi} } @article {Bonelli:2020xps, title = {Gauge theories on compact toric manifolds}, year = {2020}, month = {7}, doi = {10.1007/s11005-021-01419-9}, author = {Giulio Bonelli and Francesco Fucito and Morales, Jose Francisco and Massimiliano Ronzani and Sysoeva, Ekaterina and Alessandro Tanzini} } @article {doi:10.1142/S0129055X19500053, title = {Ground state energy of mixture of Bose gases}, journal = {Reviews in Mathematical Physics}, volume = {31}, number = {02}, year = {2019}, pages = {1950005}, abstract = {

We consider the asymptotic behavior of a system of multi-component trapped bosons, when the total particle number N becomes large. In the dilute regime, when the interaction potentials have the length scale of order O(N-1), we show that the leading order of the ground state energy is captured correctly by the Gross{\textendash}Pitaevskii energy functional and that the many-body ground state fully condensates on the Gross{\textendash}Pitaevskii minimizers. In the mean-field regime, when the interaction length scale is O(1), we are able to verify Bogoliubov{\textquoteright}s approximation and obtain the second order expansion of the ground state energy. While such asymptotic results have several precursors in the literature on one-component condensates, the adaptation to the multi-component setting is non-trivial in various respects and the analysis will be presented in detail.

}, doi = {10.1142/S0129055X19500053}, url = {https://doi.org/10.1142/S0129055X19500053}, author = {Alessandro Michelangeli and Phan Thanh Nam and Alessandro Olgiati} } @article {2018, title = {On Geometric Quantum Confinement in Grushin-Like Manifolds}, number = {SISSA;36/2018/MATE}, year = {2018}, note = {16 pages}, abstract = {We study the problem of so-called geometric quantum confinement in a class of two-dimensional incomplete Riemannian manifold with metric of Grushin type. We employ a constant-fibre direct integral scheme, in combination with Weyl{\textquoteright}s analysis in each fibre, thus fully characterising the regimes of presence and absence of essential self-adjointness of the associated Laplace-Beltrami operator.}, url = {http://preprints.sissa.it/handle/1963/35322}, author = {Matteo Gallone and Alessandro Michelangeli and Eugenio Pozzoli} } @article {Antonelli2018, title = {Global, finite energy, weak solutions for the NLS with rough, time-dependent magnetic potentials}, journal = {Zeitschrift f{\"u}r angewandte Mathematik und Physik}, volume = {69}, number = {2}, year = {2018}, month = {Mar}, pages = {46}, abstract = {

We prove the existence of weak solutions in the space of energy for a class of nonlinear Schr{\"o}dinger equations in the presence of a external, rough, time-dependent magnetic potential. Under our assumptions, it is not possible to study the problem by means of usual arguments like resolvent techniques or Fourier integral operators, for example. We use a parabolic regularisation, and we solve the approximating Cauchy problem. This is achieved by obtaining suitable smoothing estimates for the dissipative evolution. The total mass and energy bounds allow to extend the solution globally in time. We then infer sufficient compactness properties in order to produce a global-in-time finite energy weak solution to our original problem.

}, issn = {1420-9039}, doi = {10.1007/s00033-018-0938-5}, url = {https://doi.org/10.1007/s00033-018-0938-5}, author = {Paolo Antonelli and Alessandro Michelangeli and Raffaele Scandone} } @mastersthesis {Lange_2018, title = {Ground states and spectral properties in quantum field theories}, year = {2018}, school = {Friedrich-Schiller-University Jena}, type = {phd}, doi = {10.22032/dbt.35196}, url = {https://www.db-thueringen.de/receive/dbt_mods_00035196}, author = {Markus Lange} } @article {2017, title = {Gamma-Convergence of Free-discontinuity problems}, number = {SISSA;18/2017/MATE}, year = {2017}, institution = {SISSA}, abstract = {We study the Gamma-convergence of sequences of free-discontinuity functionals depending on vector-valued functions u which can be discontinuous across hypersurfaces whose shape and location are not known a priori. The main novelty of our result is that we work under very general assumptions on the integrands which, in particular, are not required to be periodic in the space variable. Further, we consider the case of surface integrands which are not bounded from below by the amplitude of the jump of u. We obtain three main results: compactness with respect to Gamma-convergence, representation of the Gamma-limit in an integral form and identification of its integrands, and homogenisation formulas without periodicity assumptions. In particular, the classical case of periodic homogenisation follows as a by-product of our analysis. Moreover, our result covers also the case of stochastic homogenisation, as we will show in a forthcoming paper.}, url = {http://preprints.sissa.it/handle/1963/35276}, author = {Filippo Cagnetti and Gianni Dal Maso and Lucia Scardia and Caterina Ida Zeppieri} } @article {BERSHTEIN201740, title = {Gauge theories on compact toric surfaces, conformal field theories and equivariant Donaldson invariants}, journal = {Journal of Geometry and Physics}, volume = {118}, year = {2017}, note = {Interactions between Geometry and Physics. A Special Issue in Honor of Ugo Bruzzo{\textquoteright}s 60th Birthday}, pages = {40 - 50}, abstract = {

We show that equivariant Donaldson polynomials of compact toric surfaces can be calculated as residues of suitable combinations of Virasoro conformal blocks, by building on AGT correspondence between $\mathcal{N}=2$\ supersymmetric gauge theories and two-dimensional conformal field theory. Talk presented by A.T. at the conference Interactions between Geometry and Physics {\textemdash} in honor of Ugo Bruzzo{\textquoteright}s 60th birthday 17{\textendash}22 August 2015, Guaruj{\'a}, S{\~a}o Paulo, Brazil, mostly based on Bawane et al. (0000) and Bershtein et al. (0000).

}, keywords = {AGT, Donaldson invariants, Equivariant localization, Exact partition function, Supersymmetry, Virasoro conformal blocks}, issn = {0393-0440}, doi = {https://doi.org/10.1016/j.geomphys.2017.01.012}, url = {http://www.sciencedirect.com/science/article/pii/S0393044017300165}, author = {Mikhail Bershtein and Giulio Bonelli and Massimiliano Ronzani and Alessandro Tanzini} } @article {PS17, title = {On the generalized Cheeger problem and an application to 2d strips}, journal = {Rev. Mat. Iberoam.}, volume = {33}, number = {1}, year = {2017}, pages = {219{\textendash}237}, doi = {10.4171/RMI/934}, author = {Pratelli, A. and Saracco, G.} } @article { refId0, title = {On the genesis of directional friction through bristle-like mediating elements}, journal = {ESAIM: COCV}, volume = {23}, number = {3}, year = {2017}, pages = {1023-1046}, abstract = {

We propose an explanation of the genesis of directional dry friction, as emergent property of the oscillations produced in a bristle-like mediating element by the interaction with microscale fluctuations on the surface. Mathematically, we extend a convergence result by Mielke, for Prandtl{\textendash}Tomlinson-like systems, considering also non-homothetic scalings of a wiggly potential. This allows us to apply the result to some simple mechanical models, that exemplify the interaction of a bristle with a surface having small fluctuations. We find that the resulting friction is the product of two factors: a geometric one, depending on the bristle angle and on the fluctuation profile, and a energetic one, proportional to the normal force exchanged between the bristle-like element and the surface. Finally, we apply our result to discuss the with the nap/against the nap asymmetry.

}, doi = {10.1051/cocv/2017030}, url = {https://doi.org/10.1051/cocv/2017030}, author = {Paolo Gidoni and Antonio DeSimone} } @article {Crismale2017, title = {Globally stable quasistatic evolution for strain gradient plasticity coupled with damage}, journal = {Annali di Matematica Pura ed Applicata (1923 -)}, volume = {196}, number = {2}, year = {2017}, month = {Apr}, pages = {641{\textendash}685}, abstract = {

We consider evolutions for a material model which couples scalar damage with strain gradient plasticity, in small strain assumptions. For strain gradient plasticity, we follow the Gurtin{\textendash}Anand formulation (J Mech Phys Solids 53:1624{\textendash}1649, 2005). The aim of the present model is to account for different phenomena: On the one hand, the elastic stiffness reduces and the plastic yield surface shrinks due to material{\textquoteright}s degradation, on the other hand the dislocation density affects the damage growth. The main result of this paper is the existence of a globally stable quasistatic evolution (in the so-called energetic formulation). Furthermore, we study the limit model as the strain gradient terms tend to zero. Under stronger regularity assumptions, we show that the evolutions converge to the ones for the coupled elastoplastic damage model studied in Crismale (ESAIM Control Optim Calc Var 22:883-912, 2016).

}, issn = {1618-1891}, doi = {10.1007/s10231-016-0590-7}, url = {https://doi.org/10.1007/s10231-016-0590-7}, author = {Vito Crismale} } @article {doi:10.1080/14029251.2017.1346348, title = {Gross-Pitaevskii non-linear dynamics for pseudo-spinor condensates}, journal = {Journal of Nonlinear Mathematical Physics}, volume = {24}, number = {3}, year = {2017}, pages = {426-464}, publisher = {Taylor \& Francis}, abstract = {

We derive the equations for the non-linear effective dynamics of a so called pseudo-spinor Bose-Einstein condensate, which emerges from the linear many-body Schr{\"o}dinger equation at the leading order in the number of particles. The considered system is a three-dimensional diluted gas of identical bosons with spin, possibly confined in space, and coupled with an external time-dependent magnetic field; particles also interact among themselves through a short-scale repulsive interaction. The limit of infinitely many particles is monitored in the physically relevant Gross-Pitaevskii scaling. In our main theorem, if at time zero the system is in a phase of complete condensation (at the level of the reduced one-body marginal) and with energy per particle fixed by the Gross-Pitaevskii functional, then such conditions persist also at later times, with the one-body orbital of the condensate evolving according to a system of non-linear cubic Schr{\"o}dinger equations coupled among themselves through linear (Rabi) terms. The proof relies on an adaptation to the spinor setting of Pickl{\textquoteright}s projection counting method developed for the scalar case. Quantitative rates of convergence are available, but not made explicit because evidently non-optimal. In order to substantiate the formalism and the assumptions made in the main theorem, in an introductory section we review the mathematical formalisation of modern typical experiments with pseudo-spinor condensates.

}, doi = {10.1080/14029251.2017.1346348}, url = {https://doi.org/10.1080/14029251.2017.1346348}, author = {Alessandro Michelangeli and Alessandro Olgiati} } @article {Fonda2016, title = {Generalizing the Poincar{\'e}{\textendash}Miranda theorem: the avoiding cones condition}, journal = {Annali di Matematica Pura ed Applicata (1923 -)}, volume = {195}, number = {4}, year = {2016}, month = {Aug}, pages = {1347{\textendash}1371}, abstract = {

After proposing a variant of the Poincar{\'e}{\textendash}Bohl theorem, we extend the Poincar{\'e}{\textendash}Miranda theorem in several directions, by introducing an avoiding cones condition. We are thus able to deal with functions defined on various types of convex domains, and situations where the topological degree may be different from \$\$\backslashpm \$\${\textpm}1. An illustrative application is provided for the study of functionals having degenerate multi-saddle points.

}, issn = {1618-1891}, doi = {10.1007/s10231-015-0519-6}, url = {https://doi.org/10.1007/s10231-015-0519-6}, author = {Alessandro Fonda and Paolo Gidoni} } @article {crismale2016globally, title = {Globally stable quasistatic evolution for a coupled elastoplastic{\textendash}damage model}, journal = {ESAIM: Control, Optimisation and Calculus of Variations}, volume = {22}, number = {3}, year = {2016}, pages = {883{\textendash}912}, publisher = {EDP Sciences}, abstract = {

We show the existence of globally stable quasistatic evolutions for a rate-independent material model with elastoplasticity and incomplete damage, in small strain assumptions. The main feature of our model is that the scalar internal variable which describes the damage affects both the elastic tensor and the plastic yield surface. It is also possible to require that the history of plastic strain up to the current state influences the future evolution of damage.

}, doi = {10.1051/cocv/2015037}, url = {https://www.esaim-cocv.org/articles/cocv/abs/2016/03/cocv150037/cocv150037.html}, author = {Vito Crismale} } @article {arici2016gysin, title = {The Gysin sequence for quantum lens spaces}, journal = {Journal of Noncommutative Geometry}, volume = {9}, number = {4}, year = {2016}, pages = {1077{\textendash}1111}, abstract = {

We define quantum lens spaces as {\textquoteleft}direct sums of line bundles{\textquoteright} and exhibit them as {\textquoteleft}total spaces{\textquoteright} of certain principal bundles over quantum projective spaces. For each of these quantum lens spaces we construct an analogue of the classical Gysin sequence in K-theory. We use the sequence to compute the K-theory of the quantum lens spaces, in particular to give explicit geometric representatives of their K-theory classes. These representatives are interpreted as {\textquoteleft}line bundles{\textquoteright} over quantum lens spaces and generically define {\textquoteleft}torsion classes{\textquoteright}. We work out explicit examples of these classes.

}, doi = {10.4171/JNCG/216}, author = {Francesca Arici and Simon Brain and Giovanni Landi} } @article {BATTAGLIA2015937, title = {A general existence result for the Toda system on compact surfaces}, journal = {Advances in Mathematics}, volume = {285}, year = {2015}, pages = {937 - 979}, abstract = {

In this paper we consider the following Toda system of equations on a compact surface:-Δu1=2ρ1(h1eu1∫Σh1eu1dVg-1)-ρ2(h2eu2∫Σh2eu2dVg-1)-Δu1=-4π∑j=1mα1,j(δpj-1),-Δu2=2ρ2(h2eu2∫Σh2eu2dVg-1)-ρ1(h1eu1∫Σh1eu1dVg-1)-Δu2=-4π∑j=1mα2,j(δpj-1), which is motivated by the study of models in non-abelian Chern{\textendash}Simons theory. Here h1,h2 are smooth positive functions, ρ1,ρ2 two positive parameters, pi points of the surface and α1,i,α2,j non-negative numbers. We prove a general existence result using variational methods. The same analysis applies to the following mean field equation-Δu=ρ1(heu∫ΣheudVg-1)-ρ2(he-u∫Σhe-udVg-1), which arises in fluid dynamics."

}, keywords = {Geometric PDEs, Min{\textendash}max schemes, Variational methods}, issn = {0001-8708}, doi = {https://doi.org/10.1016/j.aim.2015.07.036}, url = {http://www.sciencedirect.com/science/article/pii/S0001870815003072}, author = {Luca Battaglia and Aleks Jevnikar and Andrea Malchiodi and David Ruiz} } @article {agrachev2015geodesics, title = {Geodesics and horizontal-path spaces in Carnot groups}, journal = {Geometry \& Topology}, volume = {19}, number = {3}, year = {2015}, pages = {1569{\textendash}1630}, publisher = {Mathematical Sciences Publishers}, abstract = {

We study properties of the space of horizontal paths joining the origin with a vertical point on a generic two-step Carnot group. The energy is a Morse-Bott functional on paths and its critical points (sub-Riemannian geodesics) appear in families (compact critical manifolds) with controlled topology. We study the asymptotic of the number of critical manifolds as the energy grows. The topology of the horizontal-path space is also investigated, and we find asymptotic results for the total Betti number of the sublevels of the energy as it goes to infinity. We interpret these results as local invariants of the sub-Riemannian structure.

}, doi = {10.2140/gt.2015.19.1569}, author = {Andrei A. Agrachev and Alessandro Gentile and Antonio Lerario} } @mastersthesis {2015, title = {Geometric phases in graphene and topological insulators}, year = {2015}, school = {SISSA}, abstract = {This thesis collects three of the publications that the candidate produced during his Ph.D. studies. They all focus on geometric phases in solid state physics. We first study topological phases of 2-dimensional periodic quantum systems, in absence of a spectral gap, like e.g. (multilayer) graphene. A topological invariant n_v in Z, baptized eigenspace vorticity, is attached to any intersection of the energy bands, and characterizes the local topology of the eigenprojectors around that intersection. With the help of explicit models, each associated to a value of n_v in Z, we are able to extract the decay at infinity of the single-band Wannier function w in mono- and bilayer graphene, obtaining |w(x)| <= const |x|^{-2} as |x| tends to infinity. Next, we investigate gapped periodic quantum systems, in presence of time-reversal symmetry. When the time-reversal operator Theta is of bosonic type, i.e. it satisfies Theta^2 = 1, we provide an explicit algorithm to construct a frame of smooth, periodic and time-reversal symmetric (quasi-)Bloch functions, or equivalently a frame of almost-exponentially localized, real-valued (composite) Wannier functions, in dimension d <= 3. In the case instead of a fermionic time-reversal operator, satisfying Theta^2 = -1, we show that the existence of such a Bloch frame is in general topologically obstructed in dimension d=2 and d=3. This obstruction is encoded in Z_2-valued topological invariants, which agree with the ones proposed in the solid state literature by Fu, Kane and Mele.}, keywords = {Geometric phases, graphene, topological insulators, Wannier functions, Bloch frames}, author = {Domenico Monaco} } @mastersthesis {2015, title = {Gibbs-Markov-Young Structures and Decay of Correlations}, year = {2015}, school = {SISSA}, abstract = {In this work we study mixing properties of discrete dynamical systems and related to them geometric structure. In the first chapter we show that the direct product of maps with Young towers admits a Young tower whose return times decay at a rate which is bounded above by the slowest of the rates of decay of the return times of the component maps. An application of this result, together with other results in the literature, yields various statistical properties for the direct product of various classes of systems, including Lorenz-like maps, multimodal maps, piecewise $C^2$ interval maps with critical points and singularities, H\'enon maps and partially hyperbolic systems. The second chapter is dedicated to the problem of decay of correlations for continuous observables. First we show that if the underlying system admits Young tower then the rate of decay of correlations for continuous observables can be estimated in terms of modulus of continuity and the decay rate of tail of Young tower. In the rest of the second chapter we study the relations between the rates of decay of correlations for smooth observables and continuous observables. We show that if the rates of decay of correlations is known for $C^r,$ observables ($r\ge 1$) then it is possible to obtain decay of correlations for continuous observables in terms of modulus of continuity.}, keywords = {Decay of Correlations, GMY-towers}, author = {Marks Ruziboev} } @article {2015, title = {Gli abachi: antichi strumenti precursori delle moderne macchine da calcolo}, year = {2015}, url = {http://hdl.handle.net/10077/10884}, author = {Giuliano Klun} } @article {2015, title = {Global well-posedness of the magnetic Hartree equation with non-Strichartz external fields}, number = {SISSA;07/2015/MATE}, year = {2015}, institution = {SISSA}, abstract = {We study the magnetic Hartree equation with external fields to which magnetic Strichartz estimates are not necessarily applicable. We characterise the appropriate notion of energy space and in such a space we prove the global well-posedness of the associated initial value problem by means of energy methods only.}, url = {http://urania.sissa.it/xmlui/handle/1963/34440}, author = {Alessandro Michelangeli} } @mastersthesis {2014, title = {Geometry and analysis of control-affine systems: motion planning, heat and Schr{\"o}dinger evolution}, year = {2014}, school = {SISSA}, abstract = {This thesis is dedicated to two problems arising from geometric control theory, regarding control-affine systems $\dot q= f_0(q)+\sum_{j=1}^m u_j f_j(q)$, where $f_0$ is called the drift. In the first part we extend the concept of complexity of non-admissible trajectories, well understood for sub-Riemannian systems, to this more general case, and find asymptotic estimates. In order to do this, we also prove a result in the same spirit as the Ball-Box theorem for sub-Riemannian systems, in the context of control-affine systems equipped with the L1 cost. Then, in the second part of the thesis, we consider a family of 2-dimensional driftless control systems. For these, we study how the set where the control vector fields become collinear affects the diffusion dynamics. More precisely, we study whether solutions to the heat and Schr{\"o}dinger equations associated with this Laplace-Beltrami operator are able to cross this singularity, and how its the presence affects the spectral properties of the operator, in particular under a magnetic Aharonov{\textendash}Bohm-type perturbation.}, keywords = {control theory}, url = {http://urania.sissa.it/xmlui/handle/1963/7474}, author = {Dario Prandi} } @article {2014, title = {Global Structure of Admissible BV Solutions to Piecewise Genuinely Nonlinear, Strictly Hyperbolic Conservation Laws in One Space Dimension}, number = {Communications in Partial Differential Equations;Volume 39; issue 2; pp. 244-273;}, year = {2014}, publisher = {Taylor \& Francis}, abstract = {

The paper describes the qualitative structure of an admissible BV solution to a strictly hyperbolic system of conservation laws whose characteristic families are piecewise genuinely nonlinear. More precisely, we prove that there are a countable set of points Θ and a countable family of Lipschitz curves T{script} such that outside T{script} ∪ Θ the solution is continuous, and for all points in T{script}{set minus}Θ the solution has left and right limit. This extends the corresponding structural result in [7] for genuinely nonlinear systems. An application of this result is the stability of the wave structure of solution w.r.t. -convergence. The proof is based on the introduction of subdiscontinuities of a shock, whose behavior is qualitatively analogous to the discontinuities of the solution to genuinely nonlinear systems.

}, doi = {10.1080/03605302.2013.775153}, url = {http://urania.sissa.it/xmlui/handle/1963/34694}, author = {Stefano Bianchini and Lei Yu} } @article {BertolaCafasso4, title = {The gap probabilities of the tacnode, Pearcey and Airy point processes, their mutual relationship and evaluation}, journal = {Random Matrices: Theory and Applications}, volume = {02}, number = {02}, year = {2013}, pages = {1350003}, doi = {10.1142/S2010326313500032}, url = {http://www.worldscientific.com/doi/abs/10.1142/S2010326313500032}, author = {Marco Bertola and Mattia Cafasso} } @article {fonda2013, title = {Generalized Sturm-Liouville boundary conditions for first order differential systems in the plane}, journal = {Topol. Methods Nonlinear Anal.}, volume = {42}, number = {2}, year = {2013}, pages = {293{\textendash}325}, publisher = {Nicolaus Copernicus University, Juliusz P. Schauder Centre for Nonlinear Studies}, abstract = {

We study asymptotically positively homogeneous first order systems in the plane, with boundary conditions which are positively homogeneous, as well. Defining a generalized concept of Fu{\v c}{\'\i}k spectrum which extends the usual one for the scalar second order equation, we prove existence and multiplicity of solutions. In this way, on one hand we extend to the plane some known results for scalar second order equations (with Dirichlet, Neumann or Sturm-Liouville boundary conditions), while, on the other hand, we investigate some other kinds of boundary value problems, where the boundary points are chosen on a polygonal line, or in a cone. Our proofs rely on the shooting method.

}, url = {https://projecteuclid.org:443/euclid.tmna/1461248981}, author = {Alessandro Fonda and Maurizio Garrione} } @article {2013, title = {Genus stabilization for moduli of curves with symmetries}, number = {arXiv:1301.4409;}, year = {2013}, note = {21 pages, 2 figures}, publisher = {SISSA}, abstract = {In a previous paper, arXiv:1206.5498, we introduced a new homological\r\ninvariant $\\e$ for the faithful action of a finite group G on an algebraic\r\ncurve.\r\n We show here that the moduli space of curves admitting a faithful action of a\r\nfinite group G with a fixed homological invariant $\\e$, if the genus g\' of the\r\nquotient curve is sufficiently large, is irreducible (and non empty iff the\r\nclass satisfies the condition which we define as \'admissibility\'). In the\r\nunramified case, a similar result had been proven by Dunfield and Thurston\r\nusing the classical invariant in the second homology group of G, H_2(G, \\ZZ).\r\n We achieve our result showing that the stable classes are in bijection with\r\nthe set of admissible classes $\\e$.}, keywords = {group actions, mapping class group, Moduli space of curves, Teichm{\"u}ller space}, url = {http://hdl.handle.net/1963/6509}, author = {Fabrizio Catanese and Michael L{\"o}nne and Fabio Perroni} } @article {2012, title = {Gamma-convergence and H-convergence of linear elliptic operators}, journal = {Journal de Math{\'e}matiques Pures et Appliqu{\'e}es, Available online 12 September 2012}, number = {SISSA;04/2012/M}, year = {2012}, publisher = {Elsevier}, keywords = {Linear elliptic operators}, doi = {10.1016/j.matpur.2012.09.004}, url = {http://hdl.handle.net/1963/5878}, author = {Nadia Ansini and Gianni Dal Maso and Caterina Ida Zeppieri} } @article {2012, title = {Gauge Theories on ALE Space and Super Liouville Correlation Functions}, journal = {Lett. Math. Phys. 101 (2012) 103-124}, number = {arXiv:1107.4609v1;}, year = {2012}, note = {21 pages}, publisher = {SISSA}, abstract = {We present a relation between N=2 quiver gauge theories on the ALE space O_{P^1}(-2) and correlators of N=1 super Liouville conformal field theory, providing checks in the case of punctured spheres and tori. We derive a blow-up formula for the full Nekrasov partition function and show that, up to a U(1) factor, the N=2^* instanton partition function is given by the product of the character of \\\\hat{SU}(2)_2 times the super Virasoro conformal block on the torus with one puncture.}, doi = {10.1007/s11005-012-0553-x}, url = {http://hdl.handle.net/1963/4305}, author = {Giulio Bonelli and Kazunobu Maruyoshi and Alessandro Tanzini} } @article {FONDA20121369, title = {A general method for the existence of periodic solutions of differential systems in the plane}, journal = {Journal of Differential Equations}, volume = {252}, number = {2}, year = {2012}, pages = {1369 - 1391}, abstract = {

We propose a general method to prove the existence of periodic solutions for planar systems of ordinary differential equations, which can be used in many different circumstances. Applications are given to some nonresonant cases, even for systems with superlinear growth in some direction, or with a singularity. Systems {\textquotedblleft}at resonance{\textquotedblright} are also considered, provided a Landesman{\textendash}Lazer type of condition is assumed.

}, keywords = {Nonlinear dynamics, Periodic solutions}, issn = {0022-0396}, doi = {https://doi.org/10.1016/j.jde.2011.08.005}, url = {http://www.sciencedirect.com/science/article/pii/S0022039611003196}, author = {Alessandro Fonda and Andrea Sfecci} } @inbook {2012, title = {Generalized reduced basis methods and n-width estimates for the approximation of the solution manifold of parametric PDEs}, booktitle = {Springer, Indam Series, Vol. 4, 2012}, number = {SISSA Preprint;44/2012/M}, year = {2012}, publisher = {Springer}, organization = {Springer}, abstract = {The set of solutions of a parameter-dependent linear partial di fferential equation with smooth coe fficients typically forms a compact manifold in a Hilbert space. In this paper we review the generalized reduced basis method as a fast computational tool for the uniform approximation of the solution manifold. We focus on operators showing an affi ne parametric dependence, expressed as a linear combination of parameter-independent operators through some smooth, parameter-dependent scalar functions. In the case that the parameter-dependent operator has a dominant term in its affi ne expansion, one can prove the existence of exponentially convergent uniform approximation spaces for the entire solution manifold. These spaces can be constructed without any assumptions on the parametric regularity of the manifold \\r\\nonly spatial regularity of the solutions is required. The exponential convergence rate is then inherited by the generalized reduced basis method. We provide a numerical example related to parametrized elliptic\\r\\nequations con rming the predicted convergence rates.}, keywords = {solution manifold}, url = {http://hdl.handle.net/1963/6340}, author = {Toni Lassila and Andrea Manzoni and Alfio Quarteroni and Gianluigi Rozza} } @article {2012, title = {On the genus two free energies for semisimple Frobenius manifolds}, journal = {Russian Journal of Mathematical Physics. Volume 19, Issue 3, September 2012, Pages 273-298}, number = {arXiv:1205.5990;}, year = {2012}, note = {36 pages, 3 figures}, publisher = {SISSA}, abstract = {We represent the genus two free energy of an arbitrary semisimple Frobenius\\r\\nmanifold as a sum of contributions associated with dual graphs of certain\\r\\nstable algebraic curves of genus two plus the so-called \\\"genus two G-function\\\".\\r\\nConjecturally the genus two G-function vanishes for a series of important\\r\\nexamples of Frobenius manifolds associated with simple singularities as well as\\r\\nfor ${\\\\bf P}^1$-orbifolds with positive Euler characteristics. We explain the\\r\\nreasons for such Conjecture and prove it in certain particular cases.}, doi = {10.1134/S1061920812030028}, url = {http://hdl.handle.net/1963/6464}, author = {Boris Dubrovin and Si-Qi Liu and Youjin Zhang} } @article {2011, title = {Gamma-convergence of energies for nematic elastomers in the small strain limit}, journal = {Continuum. Mech. Therm.}, volume = { 23}, number = {SISSA;07/2011/M}, year = {2011}, publisher = {Springer}, chapter = {257}, abstract = {

We study two variational models recently proposed in the literature to describe the mechanical behaviour of nematic elastomers either in the fully nonlinear regime or in the framework of a geometrically linear theory. We show that, in the small strain limit, the energy functional of the first one I\\\"-converges to the relaxation of the second one, a functional for which an explicit representation formula is available.

}, keywords = {Liquid crystals}, doi = {10.1007/s00161-011-0180-2}, url = {http://hdl.handle.net/1963/4141}, author = {Virginia Agostiniani and Antonio DeSimone} } @article {9991, title = {Generalised functions of bounded deformation}, journal = {J. Eur. Math. Soc. (JEMS), to appear}, year = {2011}, publisher = {SISSA}, abstract = {

We introduce the space GBD of generalized functions of bounded deformation and study the structure properties of these functions: the rectifiability and the slicing properties of their jump sets, and the existence of their approximate symmetric gradients. We conclude by proving a compactness results for GBD, which leads to a compactness result for the space GSBD of generalized special functions of bounded deformation. The latter is connected to the existence of solutions to a weak formulation of some variational problems arising in fracture mechanics in the framework of linearized elasticity.

}, keywords = {free discontinuity problems, special functions of bounded deformation, jump set, rec- tifiability, slicing, approximate differentiability}, url = {http://hdl.handle.net/1963/6374}, author = {Gianni Dal Maso} } @article {2011, title = {Generalized matrix models and AGT correspondence at all genera}, journal = {JHEP, Volume 2011, Issue 7, 2011, Article number055}, number = {arXiv:1011.5417;}, year = {2011}, note = {This version is published in : Journal of High Energy Physics, Volume 2011, Issue 7, 2011, Article number055}, publisher = {SISSA}, abstract = {We study generalized matrix models corresponding to n-point Virasoro\r\nconformal blocks on Riemann surfaces with arbitrary genus g. Upon AGT\r\ncorrespondence, these describe four dimensional N=2 SU(2)^{n+3g-3} gauge\r\ntheories with generalized quiver diagrams. We obtain the generalized matrix\r\nmodels from the perturbative evaluation of the Liouville correlation functions\r\nand verify the consistency of the description with respect to degenerations of\r\nthe Riemann surface. Moreover, we derive the Seiberg-Witten curve for the N=2\r\ngauge theory as the spectral curve of the generalized matrix model, thus\r\nproviding a check of AGT correspondence at all genera.}, doi = {10.1007/JHEP07(2011)055}, url = {http://hdl.handle.net/1963/6568}, author = {Giulio Bonelli and Kazunobu Maruyoshi and Alessandro Tanzini and Futoshi Yagib} } @article {2011, title = {Generalized Ricci Curvature Bounds for Three Dimensional Contact Subriemannian manifolds}, number = {arXiv:0903.2550;}, year = {2011}, note = {This is a revised extended version that contains new results.}, publisher = {SISSA}, url = {http://hdl.handle.net/1963/6507}, author = {Andrei A. Agrachev and Paul Lee} } @article {2011, title = {The geometry of Maximum Principle}, journal = {Proceedings of the Steklov Institute of mathematics. vol. 273 (2011), page: 5-27 ; ISSN: 0081-5438}, number = {Proceedings of the Steklov Institute of mathematics;v.273}, year = {2011}, abstract = {An invariant formulation of the maximum principle in optimal control is presented, and some second-order invariants are discussed.}, url = {http://hdl.handle.net/1963/6456}, author = {Andrei A. Agrachev and Revaz Gamkrelidze} } @article {2010, title = {Gauge theory: from physics to geometry}, journal = {Rend. Istit. Mat. Univ. Trieste 42 (2010) 103-128}, number = {SISSA;80/2010/FM}, year = {2010}, publisher = {Istituto di matematica. Universita\\\' di Trieste}, abstract = {Maxwell theory may be regarded as a prototype of gauge theory and generalized to nonabelian gauge theory. We briey sketch the history of the gauge theories, from Maxwell to Yang-Mills theory, and the identification of gauge fields with connections on fibre bundles. We introduce the notion of instanton and consider the moduli spaces of such objects. Finally, we discuss some modern techniques for studying the topology of these moduli spaces.}, url = {http://hdl.handle.net/1963/4105}, author = {Ugo Bruzzo} } @article {2010, title = {Gene expression analysis of the emergence of epileptiform activity after focal injection of kainic acid into mouse hippocampus.}, journal = {The European journal of neuroscience. 2010 Oct; 32(8):1364-79}, number = {PMID:20950280;}, year = {2010}, publisher = {Wiley}, abstract = {

We report gene profiling data on genomic processes underlying the progression towards recurrent seizures after injection of kainic acid (KA) into the mouse hippocampus. Focal injection enabled us to separate the effects of proepileptic stimuli initiated by KA injection. Both the injected and contralateral hippocampus participated in the status epilepticus. However, neuronal death induced by KA treatment was restricted to the injected hippocampus, although there was some contralateral axonal degeneration. We profiled gene expression changes in dorsal and ventral regions of both the injected and contralateral hippocampus. Changes were detected in the expression of 1526 transcripts in samples from three time-points: (i) during the KA-induced status epilepticus, (ii) at 2 weeks, before recurrent seizures emerged, and (iii) at 6 months after seizures emerged. Grouping genes with similar spatio-temporal changes revealed an early transcriptional response, strong immune, cell death and growth responses at 2 weeks and an activation of immune and extracellular matrix genes persisting at 6 months. Immunostaining for proteins coded by genes identified from array studies provided evidence for gliogenesis and suggested that the proteoglycan biglycan is synthesized by astrocytes and contributes to a glial scar. Gene changes at 6 months after KA injection were largely restricted to tissue from the injection site. This suggests that either recurrent seizures might depend on maintained processes including immune responses and changes in extracellular matrix proteins near the injection site or alternatively might result from processes, such as growth, distant from the injection site and terminated while seizures are maintained.

}, doi = {10.1111/j.1460-9568.2010.07403.x}, url = {http://hdl.handle.net/1963/4480}, author = {Dario Motti and Caroline Le Duigou and Nicole Chemaly and Lucia Wittner and Dejan Lazarevic and Helena Krmac and Troels Torben Marstrand and Eivind Valen and Remo Sanges and Elia Stupka and Albin Sandelin and Enrico Cherubini and Stefano Gustincich and Richard Miles} } @article {DEMARCHIS20102165, title = {Generic multiplicity for a scalar field equation on compact surfaces}, journal = {Journal of Functional Analysis}, volume = {259}, number = {8}, year = {2010}, pages = {2165 - 2192}, abstract = {

We prove generic multiplicity of solutions for a scalar field equation on compact surfaces via Morse inequalities. In particular our result improves significantly the multiplicity estimate which can be deduced from the degree-counting formula in Chen and Lin (2003) [12]. Related results are derived for the prescribed Q-curvature equation.

}, keywords = {Generic multiplicity, Geometric PDE{\textquoteright}s, Morse inequalities, Scalar field equations}, issn = {0022-1236}, doi = {https://doi.org/10.1016/j.jfa.2010.07.003}, url = {http://www.sciencedirect.com/science/article/pii/S0022123610002697}, author = {Francesca De Marchis} } @article {2010, title = {On the geometric origin of the bi-Hamiltonian structure of the Calogero-Moser system}, journal = {Int. Math. Res. Not. (2010) 2010:279-296}, number = {arXiv.org;0902.0953v2}, year = {2010}, publisher = {Oxford University Press}, abstract = {We show that the bi-Hamiltonian structure of the rational n-particle (attractive) Calogero-Moser system can be obtained by means of a double projection from a very simple Poisson pair on the cotangent bundle of gl(n,R). The relation with the Lax formalism is also discussed.}, doi = {10.1093/imrn/rnp130}, url = {http://hdl.handle.net/1963/3800}, author = {Claudio Bartocci and Gregorio Falqui and Igor Mencattini and Giovanni Ortenzi and Marco Pedroni} } @article {2010, title = {The geometry emerging from the symmetries of a quantum system}, number = {SISSA;72/2009/FM}, year = {2010}, abstract = {We investigate the relation between the symmetries of a quantum system and its topological quantum numbers, in a general C*-algebraic framework. We prove that, under suitable assumptions on the symmetry algebra, there exists a generalization of the Bloch-Floquet transform which induces a direct-integral decomposition of the algebra of observables. Such generalized transform selects uniquely the set of \\\"continuous sections\\\" in the direct integral, thus yielding a Hilbert bundle. The emerging geometric structure provides some topological invariants of the quantum system. Two running examples provide an Ariadne\\\'s thread through the paper. For the sake of completeness, we review two related theorems by von Neumann and Maurin and compare them with our result.}, url = {http://hdl.handle.net/1963/3834}, author = {Giuseppe De Nittis and Gianluca Panati} } @article {mercuri2010global, title = {A global compactness result for the p-Laplacian involving critical nonlinearities}, journal = {Discrete \& Continuous Dynamical Systems-A}, volume = {28}, number = {2}, year = {2010}, pages = {469{\textendash}493}, abstract = {
We prove a representation theorem for Palais-Smale sequences involving the p-Laplacian and critical nonlinearities. Applications are given to a critical problem.

}, doi = {10.3934/dcds.2010.28.469}, url = {http://www.aimsciences.org/journals/displayArticles.jsp?paperID=5097}, author = {Mercuri, Carlo and Willem, Michel} } @article {2009, title = {Gauged Laplacians on quantum Hopf bundles}, journal = {Comm. Math. Phys. 287 (2009) 179-209}, number = {arXiv.org;0801.3376v2}, year = {2009}, publisher = {Springer}, abstract = {We study gauged Laplacian operators on line bundles on a quantum 2-dimensional sphere. Symmetry under the (co)-action of a quantum group allows for their complete diagonalization. These operators describe {\textquoteleft}excitations moving on the quantum sphere\\\' in the field of a magnetic monopole. The energies are not invariant under the exchange monopole/antimonopole, that is under inverting the direction of the magnetic field. There are potential applications to models of quantum Hall effect.}, doi = {10.1007/s00220-008-0672-5}, url = {http://hdl.handle.net/1963/3540}, author = {Giovanni Landi and Cesare Reina and Alessandro Zampini} } @article {2008, title = {A Gauss-Bonnet-like formula on two-dimensional almost-Riemannian manifolds}, journal = {Discrete Contin. Dyn. Syst. 20 (2008) 801-822}, number = {SISSA;55/2006/M}, year = {2008}, abstract = {We consider a generalization of Riemannian geometry that naturally arises in the framework of control theory. Let $X$ and $Y$ be two smooth vector fields on a two-dimensional manifold $M$. If $X$ and $Y$ are everywhere linearly independent, then they define a classical Riemannian metric on $M$ (the metric for which they are orthonormal) and they give to $M$ the structure of metric space. If $X$ and $Y$ become linearly dependent somewhere on $M$, then the corresponding Riemannian metric has singularities, but under generic conditions the metric structure is still well defined. Metric structures that can be defined locally in this way are called almost-Riemannian structures. They are special cases of rank-varying sub-Riemannian structures, which are naturally defined in terms of submodules of the space of smooth vector fields on $M$. Almost-Riemannian structures show interesting phenomena, in particular for what concerns the relation between curvature, presence of conjugate points, and topology of the manifold. The main result of the paper is a generalization to almost-Riemannian structures of the Gauss-Bonnet formula.}, doi = {10.3934/dcds.2008.20.801}, url = {http://hdl.handle.net/1963/1869}, author = {Andrei A. Agrachev and Ugo Boscain and Mario Sigalotti} } @article {2008, title = {Globally stable quasistatic evolution in plasticity with softening}, journal = {Netw. Heterog. Media 3 (2008) 567-614}, number = {SISSA;23/2007/M}, year = {2008}, abstract = {We study a relaxed formulation of the quasistatic evolution problem in the context of small strain associative elastoplasticity with softening. The relaxation takes place in spaces of generalized Young measures. The notion of solution is characterized by the following properties: global stability at each time and energy balance on each\\ntime interval. An example developed in detail compares the solutions obtained by this method with the ones provided by a vanishing viscosity approximation, and shows that only the latter capture a decreasing branch in the stress-strain response.}, url = {http://hdl.handle.net/1963/1965}, author = {Gianni Dal Maso and Antonio DeSimone and Maria Giovanna Mora and Massimiliano Morini} } @article {2008, title = {Gradient bounds for minimizers of free discontinuity problems related to cohesive zone models in fracture mechanics}, journal = {Calc. Var. Partial Differential Equations 31 (2008) 137-145}, number = {SISSA;50/2005/M}, year = {2008}, abstract = {In this note we consider a free discontinuity problem for a scalar function, whose energy depends also on the size of the jump. We prove that the gradient of every smooth local minimizer never exceeds a constant, determined only by the data of the problem.}, doi = {10.1007/s00526-006-0084-3}, url = {http://hdl.handle.net/1963/1723}, author = {Gianni Dal Maso and Adriana Garroni} } @article {2007, title = {Gaussian estimates for hypoelliptic operators via optimal control}, journal = {Atti Accad. Naz. Lincei Cl. Sci. Fis. Mat. Natur. Rend. Lincei (9) Mat. Appl. 18 (2007) 333-342}, number = {SISSA;45/2007/M}, year = {2007}, abstract = {We obtain Gaussian lower bounds for the fundamental solution of a class of hypoelliptic equations, by using repeatedly an invariant Harnack inequality. Our main result is given in terms of the value function of a suitable optimal control problem.}, doi = {10.4171/RLM/499}, url = {http://hdl.handle.net/1963/1994}, author = {Ugo Boscain and Sergio Polidoro} } @article {2006, title = {On geodesic equivalence of Riemannian metrics and sub-Riemannian metrics on distributions of corank 1}, journal = {J. Math. Sci. 135 (2006) 3168-3194}, number = {arXiv.org;math/0406111v1}, year = {2006}, abstract = {The present paper is devoted to the problem of (local) geodesic equivalence of Riemannian metrics and sub-Riemannian metrics on generic corank 1 distributions. Using Pontryagin Maximum Principle, we treat Riemannian and sub-Riemannian cases in an unified way and obtain some algebraic necessary conditions for the geodesic equivalence of (sub-)Riemannian metrics. In this way first we obtain a new elementary proof of classical Levi-Civita\\\'s Theorem about the classification of all Riemannian geodesically equivalent metrics in a neighborhood of so-called regular (stable) point w.r.t. these metrics. Secondly we prove that sub-Riemannian metrics on contact distributions are geodesically equivalent iff they are constantly proportional. Then we describe all geodesically equivalent sub-Riemannian metrics on quasi-contact distributions. Finally we make the classification of all pairs of geodesically equivalent Riemannian metrics on a surface, which proportional in an isolated point. This is the simplest case, which was not covered by Levi-Civita\\\'s Theorem.}, doi = {10.1007/s10958-006-0151-5}, url = {http://hdl.handle.net/1963/2205}, author = {Igor Zelenko} } @article {2006, title = {Glimm interaction functional for BGK schemes}, number = {SISSA;69/2005/M}, year = {2006}, url = {http://hdl.handle.net/1963/1770}, author = {Stefano Bianchini} } @article {2005, title = {Gel\\\'fand-Zakharevich Systems and Algebraic Integrability: the Volterra Lattice Revisited}, number = {SISSA;29/2005/FM}, year = {2005}, abstract = {In this paper we will discuss some features of the bi-Hamiltonian method for solving the Hamilton-Jacobi (H-J) equations by Separation of Variables, and make contact with the theory of Algebraic Complete Integrability and, specifically, with the Veselov-Novikov notion of algebro-geometric (AG) Poisson brackets.}, doi = {10.1070/RD2005v010n04ABEH000322}, url = {http://hdl.handle.net/1963/1689}, author = {Gregorio Falqui and Marco Pedroni} } @article {2005, title = {Global solutions of the Hunter-Saxton equation}, journal = {SIAM J. Math. Anal. 37 (2005) 996-1026}, number = {SISSA;104/2004/M}, year = {2005}, abstract = {We construct a continuous semigroup of weak, dissipative solutions to a nonlinear partial differential equations modeling nematic liquid crystals. A new distance functional, determined by a problem of optimal transportation, yields sharp estimates on the continuity of solutions with respect to the initial data.}, doi = {10.1137/050623036}, url = {http://hdl.handle.net/1963/2256}, author = {Alberto Bressan and Adrian Constantin} } @article {2005, title = {Ground states of nonlinear Schroedinger equations with potentials vanishing at infinity}, journal = {J. Eur. Math. Soc. 7 (2005) 117-144}, number = {SISSA;16/2004/M}, year = {2005}, abstract = {We deal with a class on nonlinear Schr\\\\\\\"odinger equations \\\\eqref{eq:1} with potentials $V(x)\\\\sim |x|^{-\\\\a}$, $0<\\\\a<2$, and $K(x)\\\\sim |x|^{-\\\\b}$, $\\\\b>0$. Working in weighted Sobolev spaces, the existence of ground states $v_{\\\\e}$ belonging to $W^{1,2}(\\\\Rn)$ is proved under the assumption that $p$ satisfies \\\\eqref{eq:p}. Furthermore, it is shown that $v_{\\\\e}$ are {\\\\em spikes} concentrating at a minimum of ${\\\\cal A}=V^{\\\\theta}K^{-2/(p-1)}$, where $\\\\theta= (p+1)/(p-1)-1/2$.}, url = {http://hdl.handle.net/1963/2352}, author = {Antonio Ambrosetti and Veronica Felli and Andrea Malchiodi} } @article {2004, title = {A geometric approach to the separability of the Neumann-Rosochatius system}, journal = {Differential Geom. Appl. 21 (2004) 349-360}, number = {arXiv.org;nlin/0307021}, year = {2004}, abstract = {We study the separability of the Neumann-Rosochatius system on the n-dimensional sphere using the geometry of bi-Hamiltonian manifolds. Its well-known separation variables are recovered by means of a separability condition relating the Hamiltonian with a suitable (1,1) tensor field on the sphere. This also allows us to iteratively construct the integrals of motion of the system.}, doi = {10.1016/j.difgeo.2004.07.001}, url = {http://hdl.handle.net/1963/2541}, author = {Claudio Bartocci and Gregorio Falqui and Marco Pedroni} } @article {2003, title = {Gaudin models and bending flows: a geometrical point of view}, journal = {J. Phys. A: Math. Gen. 36 (2003) 11655-11676}, number = {SISSA;45/2003/FM}, year = {2003}, publisher = {IOP Publishing}, abstract = {In this paper we discuss the bihamiltonian formulation of the (rational XXX) Gaudin models of spin-spin interaction, generalized to the case of sl(r)-valued spins. In particular, we focus on the homogeneous models. We find a pencil of Poisson brackets that recursively define a complete set of integrals of the motion, alternative to the set of integrals associated with the \\\'standard\\\' Lax representation of the Gaudin model. These integrals, in the case of su(2), coincide wih the Hamiltonians of the \\\'bending flows\\\' in the moduli space of polygons in Euclidean space introduced by Kapovich and Millson. We finally address the problem of separability of these flows and explicitly find separation coordinates and separation relations for the r=2 case.}, doi = {10.1088/0305-4470/36/46/009}, url = {http://hdl.handle.net/1963/2884}, author = {Gregorio Falqui and Fabio Musso} } @article {2003, title = {Geometric motion control for a kinematically redundant robotic chain: application to a holonomic mobile manipulator}, journal = {J. Robotic Syst. 20 (2003) 211-227}, year = {2003}, publisher = {Wiley}, abstract = {For kinematically redundant robotic manipulators, the extra degrees of freedom available allows freedom in the generation of the trajectories of the end-effector. In this paper, for this scope, we use techniques for motion control of rigid bodies on Riemannian manifolds (and Lie groups in particular) to design workspace control algorithms for the end-effector of the robotic chain and then to pull them back to joint space, all respecting the different geometric structures of the two underlying model spaces. The trajectory planner makes use of geometric splines. Examples of the different kinds of curves that are obtained via the De Casteljau algorithm in correspondence of different metric structures in SE(3) are reported. The feedback module, instead, consists of a Lyapunov based PD controller defined from a suitable notion of error distance on the Lie group. The motivating application of our work is a holonomic mobile manipulator for which simulation results are described in detail.}, doi = {10.1002/rob.10084}, url = {http://hdl.handle.net/1963/3019}, author = {Claudio Altafini} } @article {2002, title = {On the generation of sequential unitary gates from continuous time Schrodinger equations driven by external fields}, journal = {Quantum Inf.Process. 1 (2002),no.3,207}, number = {SISSA;43/2002/M}, year = {2002}, publisher = {SISSA Library}, doi = {10.1023/A:1019825109040}, url = {http://hdl.handle.net/1963/1614}, author = {Claudio Altafini} } @article {2002, title = {Geometry of Jacobi Curves I}, journal = {J. Dynam. Control Systems 8 (2002) 93-140}, number = {SISSA;75/2001/M}, year = {2002}, publisher = {Springer}, abstract = {Jacobi curves are deep generalizations of the spaces of \\\"Jacobi fields\\\" along Riemannian geodesics. Actually, Jacobi curves are curves in the Lagrange Grassmannians. In our paper we develop differential geometry of these curves which provides basic feedback or gauge invariants for a wide class of smooth control systems and geometric structures. Two principal invariants are the generalized Ricci curvature, which is an invariant of the parametrized curve in the Lagrange Grassmannian endowing the curve with a natural projective structure, and a fundamental form, which is a fourth-order differential on the curve. The so-called rank 1 curves are studied in more detail. Jacobi curves of this class are associated with systems with scalar controls and with rank 2 vector distributions.\\nIn the forthcoming second part of the paper we will present the comparison theorems (i.e., the estimates for the conjugate points in terms of our invariants( for rank 1 curves an introduce an important class of \\\"flat curves\\\".}, doi = {10.1023/A:1013904801414}, url = {http://hdl.handle.net/1963/3110}, author = {Andrei A. Agrachev and Igor Zelenko} } @article {2002, title = {Geometry of Jacobi curves II}, journal = {J. Dynam. Control Systems 8 (2002), no. 2, 167--215}, number = {SISSA;18/2002/M}, year = {2002}, publisher = {SISSA Library}, doi = {10.1023/A:1015317426164}, url = {http://hdl.handle.net/1963/1589}, author = {Andrei A. Agrachev and Igor Zelenko} } @article {2002, title = {Global calibrations for the non-homogeneous Mumford-Shah functional}, journal = {Ann. Sc. Norm. Super. Pisa Cl. Sci. (5) 1 (2002) 603-648}, number = {SISSA;41/2001/M}, year = {2002}, publisher = {Scuola Normale Superiore di Pisa}, abstract = {Using a calibration method we prove that, if $\\\\Gamma\\\\subset \\\\Omega$ is a closed regular hypersurface and if the function $g$ is discontinuous along $\\\\Gamma$ and regular outside, then the function $u_{\\\\beta}$ which solves $$ \\\\begin{cases} \\\\Delta u_{\\\\beta}=\\\\beta(u_{\\\\beta}-g)\& \\\\text{in $\\\\Omega\\\\setminus\\\\Gamma$} \\\\partial_{\\\\nu} u_{\\\\beta}=0 \& \\\\text{on $\\\\partial\\\\Omega\\\\cup\\\\Gamma$} \\\\end{cases} $$ is in turn discontinuous along $\\\\Gamma$ and it is the unique absolute minimizer of the non-homogeneous Mumford-Shah functional $$ \\\\int_{\\\\Omega\\\\setminus S_u}|\\\\nabla u|^2 dx +{\\\\cal H}^{n-1}(S_u)+\\\\beta\\\\int_{\\\\Omega\\\\setminus S_u}(u-g)^2 dx, $$ over $SBV(\\\\Omega)$, for $\\\\beta$ large enough. Applications of the result to the study of the gradient flow by the method of minimizing movements are shown.}, url = {http://hdl.handle.net/1963/3089}, author = {Massimiliano Morini} } @article {2001, title = {Gamma-limit of periodic obstacles}, journal = {Acta Appl. Math., 2001, 65, 207-215}, number = {SISSA;37/00/M}, year = {2001}, publisher = {SISSA Library}, abstract = {We compute the Gamma-limit of a sequence obstacle functionals in the case of periodic obstacles.}, doi = {10.1023/A:1010668530972}, url = {http://hdl.handle.net/1963/1495}, author = {Gianni Dal Maso and Paola Trebeschi} } @article {2001, title = {A Glimm type functional for a special Jin-Xin relaxation model}, journal = {Ann. Inst. H. Poincare\\\' Anal. Non Lineaire 18 (2001), no. 1, 19-42}, number = {SISSA;140/99/M}, year = {2001}, publisher = {Elsevier}, doi = {10.1016/S0294-1449(00)00124-4}, url = {http://hdl.handle.net/1963/1355}, author = {Stefano Bianchini} } @article {2001, title = {Global continuous Riemann solver for nonlinear elasticity}, journal = {Arch. Ration. Mech. An., 2001, 156, 89}, number = {SISSA;35/00/M}, year = {2001}, publisher = {SISSA Library}, doi = {10.1007/s002050100118}, url = {http://hdl.handle.net/1963/1493}, author = {Jean-Marc Mercier and Benedetto Piccoli} } @article {Bertola:CFTNPB, title = {A general construction of conformal field theories from scalar anti-de Sitter quantum field theories}, journal = {Nuclear Phys. B}, volume = {587}, number = {1-3}, year = {2000}, pages = {619{\textendash}644}, issn = {0550-3213}, author = {Marco Bertola and Bros, Jacques and Moschella, Ugo and Schaeffer, Richard} } @article {Bertola:GenerationGC, title = {Generation of primordial fluctuations in curved spaces}, journal = {Gravit. Cosmol.}, volume = {4}, number = {2}, year = {1998}, pages = {121{\textendash}127}, issn = {0202-2893}, author = {Schaeffer, Richard and Moschella, Ugo and Marco Bertola and Gorini, Vittorio} } @article {1998, title = {A generic classification of time-optimal planar stabilizing feedbacks}, journal = {SIAM J. Control Optim. 36 (1998) 12-32}, number = {SISSA;96/95/M}, year = {1998}, publisher = {SISSA Library}, abstract = {Consider the problem of stabilization at the origin in minimum time for a planar control system affine with respect to the control. For a family of generic vector fields, a topological equivalence relation on the corresponding time-optimal feedback synthesis was introduced in a previous paper [Dynamics of Continuous, Discrete and Impulsive Systems, 3 (1997), pp. 335--371]. The set of equivalence classes can be put in a one-to-one correspondence with a discrete family of graphs. This provides a classification of the global structure of generic time-optimal stabilizing feedbacks in the plane, analogous to the classification of smooth dynamical systems developed by Peixoto.}, doi = {10.1137/S0363012995291117}, url = {http://hdl.handle.net/1963/998}, author = {Alberto Bressan and Benedetto Piccoli} } @article {1998, title = {Geometric control approach to synthesis theory}, journal = {Rend. Sem. Mat. Univ. Politec. Torino 56 (1998), no. 4, 53-68 (2001)}, number = {SISSA;63/99/M}, year = {1998}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/1277}, author = {Ugo Boscain and Benedetto Piccoli} } @inbook {1998, title = {Geometry and analytic theory of Frobenius manifolds}, booktitle = {Proceedings of the International Congress of Mathematicians : Berlin 1998, August 18 - 27. II, Invited lectures. - Bielefeld : Universität Bielefeld, Fakultät für Mathematik cop. 1998. - pages : 315-326}, number = {Documenta mathematica;Extra vol.}, year = {1998}, abstract = {Main mathematical applications of Frobenius manifolds are\\r\\nin the theory of Gromov - Witten invariants, in singularity theory, in\\r\\ndifferential geometry of the orbit spaces of reflection groups and of their\\r\\nextensions, in the hamiltonian theory of integrable hierarchies. The theory\\r\\nof Frobenius manifolds establishes remarkable relationships between\\r\\nthese, sometimes rather distant, mathematical theories.}, url = {http://hdl.handle.net/1963/6488}, author = {Boris Dubrovin} } @inbook {1995, title = {Geometry of 2D topological field theories}, booktitle = {Integrable systems and quantum groups : lectures given at the 1st session of the Centro internazionale matematico estivo (C.I.M.E.) held in Montecatini Terme, Italy, June 14-22, 1995 / R. Donagi, B. Dubrovin, E. Frenkel... [et al.] ; editors, M. Francavig}, year = {1995}, publisher = {SISSA}, organization = {SISSA}, abstract = {These notes are devoted to the theory of {\textquotedblleft}equations of associativity{\textquotedblright}\\r\\ndescribing geometry of moduli spaces of 2D topological field theories.}, isbn = {3-540-60542-8}, url = {http://hdl.handle.net/1963/6483}, author = {Boris Dubrovin} } @article {1993, title = {Geometry and integrability of topological-antitopological fusion}, journal = {Communications in Mathematical Physics. Volume 152, Issue 3, March 1993, Pages 539-564}, year = {1993}, publisher = {SISSA}, abstract = {Integrability of equations of topological-antitopological fusion (being proposed\\r\\nby Cecotti and Vafa) describing the ground state metric on a given 2D topological\\r\\nfield theory (TFT) model, is proved. For massive TFT models these equations\\r\\nare reduced to a universal form (being independent on the given TFT model) by\\r\\ngauge transformations. For massive perturbations of topological conformal field theory\\r\\nmodels the separatrix solutions of the equations bounded at infinity are found\\r\\nby the isomonodromy deformations method. Also it is shown that the ground state\\r\\nmetric together with some part of the underlined TFT structure can be parametrized\\r\\nby pluriharmonic maps of the coupling space to the symmetric space of real positive\\r\\ndefinite quadratic forms.}, doi = {10.1007/BF02096618}, url = {http://hdl.handle.net/1963/6481}, author = {Boris Dubrovin} } @article {1990, title = {G-convergence of monotone operators}, journal = {Ann. Inst. H. Poincare\\\' Anal. Non Lin{\'e}re 7 (1990), no. 3, 123-160}, number = {SISSA;84/88/M}, year = {1990}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/680}, author = {Valeria Chiad{\`o} Piat and Gianni Dal Maso and Anneliese Defranceschi} } @article {1990, title = {A general chain rule for distributional derivatives}, journal = {Proc. Amer. Math. Soc. 108 (1990), no. 3, 691-702}, number = {SISSA;54/88/M}, year = {1990}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/650}, author = {Luigi Ambrosio and Gianni Dal Maso} } @article {1990, title = {A general existence theorem for boundary value problems for ordinary differential equations}, journal = {Nonlinear Anal. 15 (1990), no. 10, 897--914}, number = {SISSA;36/88/M}, year = {1990}, publisher = {SISSA Library}, doi = {10.1016/0362-546X(90)90073-P}, url = {http://hdl.handle.net/1963/632}, author = {Giovanni Vidossich} } @article {1988, title = {Generalized Baire category and differential inclusions in Banach spaces.}, journal = {J. Differential Equations 76 (1988), no. 1, 135-158.}, number = {SISSA;56/87/M}, year = {1988}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/538}, author = {Alberto Bressan and Giovanni Colombo} } @article {1987, title = {Graded Chern-Simons terms}, journal = {Phys. Lett. B 192 (1987), no. 1-2, 81-88.}, number = {SISSA;27/87/FM}, year = {1987}, publisher = {SISSA Library}, doi = {10.1016/0370-2693(87)91146-4}, url = {http://hdl.handle.net/1963/508}, author = {Giovanni Landi and Giuseppe Marmo} }