Wednesday, 16. May 2018, 14:00

Invitation to a talk: Marcelo Terra Cunha, Wednesday, May 16th 2018, 2 pm at the IQOQI Seminar Room

Coloured Graph approach for Contextuality with parts

In 2014, together with some colleagues, we addressed the question: how to impose Bell locality constraints in order to refine Cabello-Severini-Winter graph approach to contextuality for Bell inequalities. The solution was the Coloured Graph Approach, where, given a Bell inequality, a coloured graph is defined and a new graph invariant, the coloured Lovász number, plays the role of the Tsirelson bound. Since them, we have some new results. First a reciprocal characterisation: given a coloured graph, how to recognise if it correspond to some Bell inequality? Given a Bell coloured graph, in which Bell scenarios this inequality applies? Regarding the basic building blocks of contextual graphs, odd cycles and their complements, is it possible to find a Bell colouring where the coloured Lovász is the same as Lovász number, i.e., is it possible to get the maximal quantum contextuality of these essential elements from Bell scenarios? This is a joint work in progress, with Rafael Rabelo and Adán Cabello. In the talk, I will give answers to all those questions, and formulate some other questions to which we only have partial answers.