Date: 31 de Outubro de 2023, 12h

Venue: Sala de Seminários do DMAT
online: https://videoconf-colibri.zoom.us/j/93344876599?wd=ejkrZ3FpYkh0NE1YV3NCdGFMOGw3QT09

Speaker: Dylan McDermott, Reykjavik University

Abstract: Monads, and their presentations through operations and equations, have been used to study and model computations involving effects, such mutable state and nondeterministic choice. Graded monads are a more recent generalization that are connected to graded algebraic structures such as graded rings, and they have also proven to be useful for computational effects. The corresponding notion of presentation turns out to be too rigid to present some computational effects, and this rigidity also reveals that the connection with graded algebraic structures is weaker than one might hope. I will talk about the connection between graded monads and computational effects and the problem with presentations of graded monads. I will then discuss how the problem can be rectified, by introducing the notion of flexibly graded presentation of a graded monad.

This talk is based on joint work with Shin-ya Katsumata, Tarmo Uustalu, and Nicolas Wu, described in the following papers:  
- Dylan McDermott and Tarmo Uustalu, Flexibly graded monads and graded algebras, MPC 2022
- Shin-ya Katsumata, Dylan McDermott, Tarmo Uustalu and Nicolas Wu, Flexible presentations of graded monads, ICFP 2022