Ekaterina Kubyshkina will present joint work with M. Petrolo “What is normal?” at the 1st MoLoCo (Modal Logic Collective) meeting held at the University of Bologna on May 30rd, 2025.

TITLE. What is normal?

ABSTRACT. On the basis of the definition of a normal modal system, it is common to distinguish between normal and non-normal modal operators. However, we argue that the standard definition of a normal operator in the literature leads to at least two problems. First, it induces a mismatch between the normality of a system and the attribution of normality to an operator of this system. Second, the standard definition is insensitive to different occurrences of the possibility operator in various normal and non-normal systems. We introduce a definition of normal operator which is not affected by either of these problems, and discuss its applications both to the monomodal and to the multimodal settings.