# Blog de la Biblioteca de Matemàtiques i Informàtica

## SIMBa: Restricted and unrestricted weak type operators on Lorentz spaces

Dilluns, 16 de juny, se celebrarà una nova sessió del Seminari Informal de Matemàtiques de Barcelona (SIMBa).

Speaker: Tommaso Bruno
Universitat: Università degli Studi di Milano-Bicocca /UB

Data: dilluns, 16 de juny de 2014
Hora: 17:45, cafè; 18:00, inici. 19:00: Assemblea. 19:30: Inici preparatius sopar de germanor.
Lloc: Aula IMUB (al terrat), Facultat de Matemàtiques de la Universitat de Barcelona.

Títol: Restricted and unrestricted weak type operators on Lorentz spaces.
Resum: Many important operators in harmonic analysis are not bounded when acting between certain function spaces, and only satisfy a boundedness inequality if restricted to characteristic functions of measurable sets. We shall study when this restricted property is equivalent to a stronger type of boundedness of the operator. Lorentz spaces arise as the natural context for these problems and a brief introduction will be worthwhile; we will also show that the measure space on which they are considered strongly influences the behaviour of the operator. In particular, we shall focus on restricted weak type (1,1) that turns out to be the critical and most interesting case. Many positive and few negative results have been proved but in some situations optimal conditions are still unknown. In the hope of receiving useful suggestions, some open questions will be presented at the end.

Anunci especial: Recordem que en acabar el seminari farem el sopar de final de curs.

Si voleu rebre informació dels propers seminaris us podeu subscriure a la llista de correu. Si voleu contactar amb els responsables podeu escriure un missatge a seminari(dot)simba(at)ub(dot)edu.