Biexactness and the (AO)-property can be considered as analytic counterparts of hyperbolicity for discrete groups. Motivated by the problem of determining whether they are equivalent, I will discuss an approach to the study of regularity properties of boundary actions/representations based on measurable dynamics. This approach will be used to study SL(3,Z) and to answer a question posed by C. Anantharaman-Delaroche.

Some bibliography:
https://arxiv.org/abs/2111.13885
https://arxiv.org/abs/2305.16277
https://arxiv.org/abs/2410.01447

A basic problem in symplectic topology is the classification of Lagrangian submanifolds up to Hamiltonian isotopy. There is growing evidence that this is impossible to solve, but one can hope to have a coarser classification by proving that finitely many Lagrangians generate the Fukaya category. I will illustrate some concrete examples where we know how to do this, some in which we do not, and a new technique called decoupling that could partially bridge the gap.

In this talk I will present the recent paper by Fewster, Janssen, Loveridge, Waldron and myself: "Quantum reference frames, measurement schemes and the type of local algebras in quantum field theory." In this work we show how mathematically rigorous notion of quantum reference frames allows to generalize the results of Chandrasekaran, Longo, Penington and Witten on observables in de Sitter space. The main idea is to study the joint algebra associated to the system together with the reference frame in the presence of symmetries. If both the system and the reference frame are covariant under some symmetry group, the construction of the invariant joint algebra very naturally involves crossed products.

We are concerned with a generalization to the singular case of a result of C.C. Chen e C.S. Lin [Comm. An. Geom. 1998] for Liouville-type equations with rough potentials. The singular problem is actually more delicate and results in a nontrivial variation of the regular case. Part of the arguments of Chen-Lin can be adapted to the singular case by means of an isoperimetric inequality for surfaces with conical singularities. The rest of the proof actually requires a different approach, due to the loss of translation invariance of the problem.
NB:This talk is part of the activity of the MIUR Excellence Department Project MATH@TOV CUP E83C23000330006

We will discuss modular compactifications of M_{g,n} (the moduli space of smooth curves) and their birational geometry within the framework of the Hassett-Keel program. We classify the open substacks of canonically polarized curves with nodes, cusps, and tacnodes having a proper good moduli space. Using the S- and Theta-completeness criteria, we transform the problem into a combinatorial one where compactifications and flips can be described using cluster algebra theory. This approach yields a complete description of the Q-factorialization fan of (overline{M}_{g,n}(7/10)) as a cluster fan.

  The induced character formula in classical representation theory can be used, among other things, to describe the dimension of coinvariants of a representation in terms of its character. In this talk, I will explain how this formula is related to the multiplicativity of Euler characteristics in algebraic topology, and, in a more homotopy-coherent context, to the composability of so-called Becker-Gottlieb transfers, which are "wrong-way maps" in singular (co)homology; by describing a general formula to compute "dimensions of homotopy colimits". If time permits, I will discuss the most general case in which composability of Becker-Gottlieb transfers is now known. This is based on joint works with Carmeli-Cnossen-Yanovski, Klein-Malkiewich (and the last part with Volpe-Wolf).
  This talk is part of the activity of the MIUR Excellence Department Project Mat-Mod@TOV (CUP E83C23000330006).

  I will report on a recent work in collaboration with F. Cavalletti and A. Lerario, where we study complex projective hypersurfaces seen as probability measures on the projective space.
  Our guiding question is: “What is the best way to deform a complex projective hypersurface into another one?"
  Here the word best means from the point of view of measure theory and mass optimal transportation. In particular, we construct an embedding of the space of complex homogeneous polynomials into the probability measures on the projective space and study its intrinsic Wasserstein metric.The Kähler structure of the projective space plays a fundamental role and we combine different techniques from symplectic geometry to the Benamou-Brenier dynamical approach to optimal transportation to prove several interesting facts. Among them we show that the space of hypersurfaces with the Wasserstein metric is complete and geodesic: any two hypersurfaces (possibly singular) are always joined by a minimizing geodesic. Moreover outside the discriminant locus, the metric is induced by a Kähler structure of Weil-Petersson type. In the last part I will give an application to the condition number of polynomial equations solving.
  This talk is part of the activity of the MIUR Excellence Department Project Mat-Mod@TOV (CUP E83C23000330006).

In this talk I will present a recent work in which the strong ill-posedness of the two-dimensional Boussinesq system is proven. I will show explicit examples of initial data with vorticity and density gradient in L^∞ (R²) for which the horizontal density gradient has a strong norm inflation in infinitesimal time. This is a joint work with Roberta Bianchini (CNR) and Lars Eric Hientzsch (Bielefeld University).
NB:This talk is part of the activity of the MIUR Excellence Department Project MATH@TOV CUP E83C23000330006

Through the lens of Minimal Model Program, the classification of algebraic varieties can be summarised in 2 steps. First MMP allows to decompose a variety with mild singularities, birationally, into a tower of fibrations whose general fibres have ample, anti-ample or numerically trivial canonical divisor. The natural second step is to study these 3 classes, e.g. by their moduli theory or other properties that shed light on all elements in the classes. It turns out a very important property is boundedness: a collection of varieties is bounded when the elements of the given collection can be parametrised using a finite type geometric space. This is crucial in the construction of proper moduli spaces of finite type. Moreover if a given collection of algebraic varieties is bounded (in char 0) then the topological types of their underlying analytic spaces belong to finitely many homeomorphism classes and their topological invariants come in finitely many versions. While over the past 15 years several breakthroughs have completely settled the question of boundedness (and subsequent construction of moduli spaces) in the case of log canonical models (varieties/pairs with ample canonical divisor) and Fano varieties (anti-ample case), the situation is still quite unclear in the case of trivial numerical divisor. I will try to explain what is known or not, and which challenges make the situation quite more complicated than the other cases. I will explain how we can overcome most issues if we assume that a K-trivial variety is endowed with a fibration structure of relative dimenesion one. The seminar is based on various works I developed over the past 10 years with G. Di Cerbo, C. Birkar, S. Filipazzi and C. Hacon. Time permitting I will talk about work in progress with P. Engel, S. Filipazzi, F. Greer, M. Mauri showing various new boundedness results for K-trvial varieties fibered in K3 surfaces or abelian varieties

Operads are algebraic structures capturing multi-ary operations. The little disks operads, encoding operations on iterated loop spaces, are fundamental examples. Voronov introduced Swiss-Cheese operads, which generalize little disks to relative loop spaces of pairs of spaces. While the little disks operads are formal (their cohomology determines their rational homotopy type), the standard Swiss-Cheese operads are not. We will discuss why higher-codimensional Swiss-Cheese operads are formal, and why Voronov's original version is not. This non-formality result, stemming from joint work with R. V. Vieira, leads to questions about truncations and Massey products.
This talk is part of the activity of the MIUR Excellence Department Project Mat-Mod@TOV (CUP E83C23000330006).