Carə tuttə, Vi invitiamo al seminario dei Baby Geometri della prossima settimana: Martedì 03 Dicembre 2024, alle ore 11:30 Presso l’Aula Mancini del Palazzo della Carovana Gaëtan Simian (Université de Genève) terrà un seminario dal titolo: The Arf invariant of colored links di cui riportiamo l'abstract: The Arf invariant is a modulo 2 integer associated to a non-singular quadratic form over the field F2. In 1965, Robertello applied this theory to Seifert forms, leading to an invariant of a certain class of oriented links. Colored links are a natural generalisation of oriented links, where the components are grouped into sublinks. Several invariants of oriented links, such as the Alexander module and the Levine-Tristram signature, admit natural multivariable extensions to colored links via so-called "generalised Seifert surfaces". In this talk, I will define these notions and briefly explain how to use generalised Seifert surfaces to extend the Arf-Robertello invariant to colored links. Unfortunately, these extensions turn out to be determined by the linking numbers. Vi ricordiamo che potrete trovare informazioni sui prossimi seminari sul nostro sito https://sites.google.com/view/babygeometri. Tutte le persone interessate sono invitate a partecipare. A presto, Elena Bogliolo Pietro Capovilla Alessio Di Prisa Giovanni Framba Ervin Hadžiosmanović