1. A. Baltag and S. Smets, A Qualitative Theory of Dynamic Interactive Belief Revision, Texts in Logic and Games, 3:9-58, Amsterdam University Press, 2008. Reprinted in: Readings in Formal Epistemology, Springer Graduate Texts in Philosophy, vol 1. Springer, 2016. http://dx.doi.org/10.1007/978-3-319-20451-2_39
This paper, written in 2008 and reprinted in 2016, extends the work on dynamic epistemic logic and makes it compatible with methods used in belief revision. The result is a powerful logical system that can model a large variety of epistemic concepts used in formal epistemology.
2. A. Baltag and S. Smets. Reasoning about Quantum Information: An Overview of Quantum Dynamic Logic, Applied Sciences, MDPI, 4458, 12(9), 2022. http://dx.doi.org/10.3390/app12094458
This is an overview paper of the main line of work on dynamic quantum logic, it focuses on the presentation of a quantum analogue of one of the most widespread models of concurrent computation (labelled transition systems or multi-modal Kripke frames), which abstracts the main dynamic-informational features of the standard model (Hilbert spaces) for quantum mechanics. This presentation is used to gain a better understanding of the specific features of quantum information.
3. A. Baltag and S. Smets, Learning what Others Know, in L. Kovacs and E. Albert (eds.), LPAR23 proceedings, online EPiC Series in Computing, 2020. https://doi.org/10.29007/plm4
This paper introduces several new contributions in the area of logic, it provides a model to compare the epistemic states of groups of classical agents and introduces an axiomatization for a logic that has the new collective attitude called ‘common distributed knowledge’.
4. A. Baltag, N. Bezhanishvili, A. Ozgun, S. Smets. A Topological Approach to Full Belief. Journal of Philosophical Logic, 48(2):205-244, 2019. http://dx.doi.org/10.1007/s10992-018-9463-4
5. Baltag, A., Bezhanishvili, N., Özgün, S. Smets. Justified belief, knowledge, and the topology of evidence. Synthese 200:512, 2022. http://dx.doi.org/10.1007/s11229-022-03967-6
In this line of work (4 and 5), we use methods coming from topology combined with insights from epistemic logic to provide a new type of semantics for notions of evidence, evidence-based justifications, belief, and knowledge.
6. S. Smets and F. R. Velázquez-Quesada, How to Make Friends: A Logical Approach to Social Group Creation, Lecture Notes in Computer Science, 10455:277-390, 2017. http://dx.doi.org/10.1007/978-3-662-55665-8_26
7. A. Baltag, Z. Christoff, R. Rendsvig, S. Smets. Dynamic Epistemic Logics of Diffusion and Prediction in Social Networks, Studia Logica, 107:489–531, 2019. http://dx.doi.org/10.1007/s11225-018-9804-x
The work in 6 and 7 shows how dynamic epistemic logic can be applied to reason about social networks. In particular the work in 7 illustrates the use of logic to model opinion diffusion in social networks. This work treats agents in a network not as mere nodes in a graph but equips them with full reasoning powers which makes them applicable in the social sciences.
8. A. Baltag and S. Smets. Modeling correlated information change: from conditional beliefs to quantum conditionals, Soft computing, 21(6):1523-1535, 2017. http://dx.doi.org/10.1007/s00500-017-2499-5
In this work we provide a new unified logical setting that encodes both classical information and quantum information to reason about the informational aspects of quantum measurements as well as classical belief change and counterfactual reasoning (in single-agent environments). This work shows that a dynamic modal-logic perspective proves to be very powerful to draw connections between the classical and quantum information-theoretic research areas.
9. A. Baltag, J. Bergfeld, K. Kishida, J. Sack, S. Smets, S. Zhong. PLQP & Company: Decidable Logics for Quantum Algorithms. International Journal of Theoretical Physics, 53(10):3628-3647, 2014. http://dx.doi.org/10.1007/s10773-013-1987-3
We constructed a general proof method to show the decidability of probabilistic quantum logical systems. This result shows for the first time that this quantum logic has a computational advantage over its classical first- (and higher-) order variants which are known to be undecidable. Decidability is an important feature that logical systems can have, as it opens up the road for implementations e.g. when searching for a logical basis of our new quantum programming languages.
10. A. Baltag, J. Bergfeld, K. Kishida, J. Sack, S. Smets and S. Zhong. Quantum Probabilistic Dyadic Second-Order Logic. Lecture Notes in Computer Science, 8071:64-80, 2013. http://dx.doi.org/10.1007/978-3-642-39992-3_9
In this work, we continued the development of the dynamic quantum logical formalism to reason about compound quantum systems. We co-designed a new probabilistic setting to express the formal correctness of several quantum information protocols: Quantum Leader Election, the Deutsch-Josza algorithm and a Quantum Search Algorithm.
11. A. Baltag and S. Smets, Logic meets Wigner’s Friend (and their Friends), International Journal of Theoretical Physics, 63, article number 97, 2024.
In this work we explore how the classical principles of knowledge – as formalized in epistemic logic – interact with the principles of quantum mechanics. We pursue this topic by focusing on the role of the observer in the foundations of quantum mechanics. More specifically, we zoom-in on variations of Wigner's-Friend thought experiment.