Location

The workshop is going to take place at the Lorentz Center in the Snellius building in Leiden. This is located at Niels Bohrweg 1 on the 2nd floor. See here for a map and here for travel information.

Programme

• Ugo Montanari, 10:00 – 10:45

• Bart Jacobs, 11:00 – 11:45

• Bartek Klin, 11:45 – 12:30

Causal Trees, Finally

Ugo Montanari ¹

Causal trees were introduced in 1989 by Philippe Darondeau and Pierpaolo Degano. The idea is to record causality dependencies in processes and in their actions. As such, causal trees sit between interleaving models and truly concurrent ones and they originate an abstract, event-based bisimulation semantics for causal processes, where, intuitively, minimal causal trees represent the semantic domain. In the talk, we substantiate this feeling by first defining a nominal, compositional operational semantics based on History-Dependent automata. Then we apply categorical techniques, based on presheaves and named-sets, showing that causal trees form the final coalgebra semantics of a suitable coalgebraic representation of causal behaviour.

Joint work with Roberto Bruni and Matteo Sammartino.

Introduction to Effectus Theory

Bart Jacobs ²

TBA

Distributive laws of monads over comonads can’t be formatted

Bartek Klin ³

Distributive laws of monads over comonads are the most powerful type of laws considered in bialgebraic operational semantics. For at least a decade it has been hoped that they would provide a general syntactic rule format for compositionality of bisimulation, generalizing both the formats of GSOS and safe ntree.

That hope was false. I will explain why.