Helena Del Río, University of Granada, Denseness results and Bollobás-type theorems for range strongly exposing operators, Thursday, April 09, 2026, time 14:30, Aula seminari III piano
Abstract:Abstract:
We present a new class of bounded linear operators on Banach spaces called Range strongly exposing operators (RSE, in short), which form a natural intermediate class between classical norm-attaining operators and Bourgain's absolutely strongly exposing operators (1977). In the first part of the talk, several foundational results on the denseness of norm-attaining operators are extended to this new setting. In particular, we improve some classical results by Uhl (1976) and Schachermayer (1983), and get some analogous to Acosta (1999). In the second part, we address Bollobás-type theorems for RSE operators, that is, results that allow us approximating simultaneously an operator and a point where the norm is almost attained, and we show that this property provides new characterisations of uniform convexity and complex-uniform convexity. This talk is based on joint works with Geunsu Choi, Audrey Fovelle, Mingu Jung and Miguel Martín.

Mattia Freguglia, Bocconi, Minimizing and min-max Yamabe metrics on conical manifolds, Thursday, April 02, 2026, time 14:30, Aula seminari, terzo piano
Abstract:Abstract:
We discuss the existence of Yamabe metrics on conical manifolds with Ricci-flat tangent cones at singular points. We prove an analogue of Aubin’s classical result, obtaining solutions as minimizers of the Yamabe quotient. In contrast to the smooth case, when this condition fails, minimizers may not exist. In dimension four, and in the presence of at least two Z/2Z-orbifold points, we still obtain solutions via a min-max variational scheme. Based on joint works with Andrea Malchiodi (SNS) and Francesco Malizia (SNS).

Giulio Schimperna, Università di Pavia, Some recent results on the so-called "Cahn-Hilliard-Keller-Segel" system, Thursday, March 19, 2026, time 14:30, Aula Seminari, terzo piano
Abstract:Abstract:
In this talk we will present some mathematical results regarding the so-called "Cahn-Hilliard-Keller-Segel'' system. This is a recently proposed model which couples the Cahn-Hilliard system for phase separation with a further equation describing the evolution of an additional variable $\sigma$. The main application of the model refers to tumor growth processes, in which the phase variable $\varphi$ represents the local proportion of active cancer cells, whereas $\sigma$ denotes the concentration of a chemical substance (for instance a nutrient or a drug) affecting the evolution of the tumor. In this setting, the equation for $\sigma$ may be characterized by a quadratic cross-diffusion term similar to that occurring in the Keller-Segel model for chemotaxis. In the talk we will discuss about existence, uniqueness and regularity of several classes of solutions ("weak", "strong" and "entropic") under various assumptions on the mass and nutrient source terms occurring in the system; in a specific situation we will also analyze the long-time behavior of solutions under the perspective of infinite-dimensional dynamical systems.

Giacomo Sodini, TU Wien, Sobolev functions on spaces of measures and applications, Thursday, March 05, 2026, time 14:30, Aula seminari, III piano
Abstract:Abstract:
After a brief introduction to the Wasserstein and Hellinger-Kantorovich distances on the space of (probability) measures, we discuss two approaches to the definition of differentiable functions on spaces of measures. Provided a suitable (and in a way canonical) reference measure is chosen, we show that the two approaches coincide. Finally, we discuss some possible applications such as the study of HJB equations and stochastic processes on spaces of measures.

Fabio E. G. Cipriani, Politecnico di Milano, Existence, degeneracy, discreteness and stability of ground states by logarithmic Sobolev inequalities on Clifford algebras, Thursday, Febraury 26, 2026, time 14:30, Aula seminari III piano
Abstract:Abstract:
We prove existence, finite degeneracy, discreteness and stability of ground states of energy forms satisfying logarithmic Sobolev inequalities with respect to not necessarily tracial states on von Neumann algebras. The results are then applied to discuss existence and properties of ground states of Hamiltonians considered by L. Gross in QFT, describing, on a suitable Clifford algebra, spin 1/2 Dirac particles, subject to interactions with an unbounded external scalar field.

Alberto Farina, Université de Picardie Jules Verne, One-dimensional symmetry results for semilinear equations and inequalities on half-spaces, Tuesday, Febraury 24, 2026, time 14:30, Aula seminari, terzo piano
Abstract:Abstract:
We consider non-negative solutions, possibly unbounded, to the semilinear equation $-\Delta u=f(u)$ in the upper half-space $R^N_+$ and we prove new one-dimensional symmetry results. Some Liouville-type theorems are also proven in the case of differential inequalities in $R^N_+$, even without imposing any boundary condition. Although subject to dimensional restrictions, our results apply to a broad family of functions $f$. In particular, they apply to all non-negative function $f$ that behaves at least linearly at infinity.