Dear all,
on Monday we will have our first LIRa session in the new semester.
Speakers: Aybüke Özgün and Ana Lucia Vargas Sandoval
(both ILLC, Amsterdam)
Date and Time: Monday, September 4th 2017, 13:00-14:30
Venue: ILLC Seminar Room F1.15, Science Park 107.
Title: Topo-Logic as a dynamic-epistemic logic
(toward a logic for Learning Theory).
Abstract. In this talk, we investigate a natural extension of
Topo-Logic of Moss and Parikh (1992), obtained by adding to it dynamic
modalities for ‘topological public announcements’ in the style of
Bjorndahl (2017). In other words, we revisit Topo-Logic as a dynamic
epistemic logic with public announcements. The resulting “Dynamic
Topo-Logic” forms a logic of evidence-based knowledge, knowability,
learning of new evidence, and stability (of some truth φ) under any
further (true) evidence-acquisition. Moreover, we also talk about a
topological arbitrary announcement modality studied by van Ditmarsch
et al. (2015), and investigate its interplay with the effort modality.
We therefore develop a formal, topological framework that clarifies
the intuitively obvious, yet formally elusive connection between the
dynamic notions effort and its seemingly special instances: public and
arbitrary announcements.
We give a complete axiomatization for this Dynamic Topo-Logic, which
is — we argue — epistemically more intuitive and, in a sense,
simpler than the standard axioms of Topo-Logic. Our completeness proof
is also more direct, making use of a standard canonical model
construction. Moreover, we study the relations between this extension
and other known logical formalisms, showing in particular that it is
co-expressive with the simpler and older logic of interior and global
modality, which immediately provides an easy decidability proof both
for the original Topo-Logic and for our extension. In turn, the effort
modality also helps to simplify and streamline the axiomatization of
the topological arbitrary announcement logic.
If time permits, we also discuss a variant of the Dynamic Topo-Logic
as a Dynamic Logic for Learning Theory, and use it to characterize
various notions of knowledge, belief, and learning.
The first part of the talk is joint work with Alexandru Baltag, and
the second part is joint work with Alexandru Baltag, Nina
Gierasimczuk, and Sonja Smets.
Hope to see you there!
The LIRa team
