We work with shift spaces defined by infinite sequences of simple combinatorial rules called substitutions. To such a system we associate a renormalization cocycle, intimately related with a multidimensional continued fraction algorithm. Under…
Categoria evento: Seminars
Continuous family of conserved energies for NLS, KdV and mKdV – Herbert Koch (Bonn)
InthistalkbasedonjointworkwithKienzlerandVazquezIwill explainhowCaffarelli’sstrategyofprovingregularityforfree boundaryproblemscanbeimplementedfortheporousmediumequation. ElementsoftheproofisaglobalexistenceresultforLipschitz…
Coarse algebraic topology – Luigi Caputi (University of Regensburg)
Coarse geometry was born from the informal idea of studying the large scale structure of metric spaces. As the abstraction of continuous functions between them led to the concept of open sets and topological spaces, the study of the large scale…
Knots, Galois groups and Massey products – Claudio Quadrelli (Università di Firenze)
Cohomological Massey products were defined in the ’50s as higher cohomology operations generalizing the cup product, to provide a “cohomological translation” of the Milnor invariants, which describe the higher linking properties of the knots in a…
Nonlocal phase transitions and minimal surfaces – Enrico Valdinoci
We present some recent results on a nonlocal version of the Allen-Cahn equation, which is also related, at a large scale, to surfaces which minimise a nonlocal perimeter functional. We discuss some features, such as symmetry property, regularity and…
Gruppi Kac-Moody, minori generalizzati e rappresentazioni di quiver – Salvatore Stella (Sapienza Università di Roma)
La teoria delle rappresentazioni dei gruppi Kac-Moody e quella dei quiver aciclici presentano entrambe, nel caso generale, una struttura tripartita. Le rappresentazioni di un gruppo Kac-Moody G sono divise naturalmente in tre classi (peso più alto,…
How to “synthesize” sub-fixed point sets into the global one just by looking inside groups? – Masato Mimura (Tohoku university e EPF Lausanne)
Consider a group G action on a metric space X by isometries, andsubgroups M_1,…, M_l. One interesting and important problem isto studyconditions underwhichnon-emptyness of each M_i-fixed points ensures thatof global (G-)fixed points. One extreme…
A direct approach to an epiperimetric inequality for Free-Boundary problems – Luca Spolaor
Using a direct approach, we prove a 2-dimensional epiperimetric inequality for the one-phase problem in the scalar and vectorial cases and for the double-phase problem. From this we deduce the $C^{1,α}$ regularity of the free-boundary in the scalar…
Introduzione agli omeomorfismi quasi-conformi – Kirill Kuzmin (Università di Pisa)
Gli omeomorfismi quasi-conformi sono definiti rilassando la condizione di conformalità con una disuguaglianza. Essi hanno trovato applicazione in numerose aree della Matematica. In questo seminario daremo una breve introduzione agli omeomorfismi…
A randomized version of the Littlewood Conjecture – Part II: discussion – Henna Koivusalo (University of Vienna)
The Littlewood Conjecture in Diophantine approximation can be thought of as a problem about covering the plane by a union of hyperbolas centered at rational points. In this paper we consider the problem of translating the center of each hyperbola by…