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Hans Ditmarsch [20]Hans van Ditmarsch [4]Hans P. Van Ditmarsch [1]
  1. Contingency and Knowing Whether.Jie Fan, Yanjing Wang & Hans van Ditmarsch - 2015 - Review of Symbolic Logic 8 (1):75-107.
    A proposition is noncontingent, if it is necessarily true or it is necessarily false. In an epistemic context, ‘a proposition is noncontingent’ means that you know whether the proposition is true. In this paper, we study contingency logic with the noncontingency operator? but without the necessity operator 2. This logic is not a normal modal logic, because?→ is not valid. Contingency logic cannot define many usual frame properties, and its expressive power is weaker than that of basic modal logic over (...)
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  2.  30
    Prolegomena to Dynamic Logic for Belief Revision.Hans P. Van Ditmarsch - 2005 - Synthese 147 (2):229-275.
    In ‘belief revision’ a theory\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\cal K}$$\end{document} is revised with a formula φ resulting in a revised theory \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\cal K}\ast\varphi$$\end{document}. Typically, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\neg\varphi$$\end{document} is in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\cal K}$$\end{document}, one has to give up belief in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\neg\varphi$$\end{document} by a process (...)
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  3.  20
    The Secret of My Success.Hans Ditmarsch & Barteld Kooi - 2006 - Synthese 151 (2):201-232.
    In an information state where various agents have both factual knowledge and knowledge about each other, announcements can be made that change the state of information. Such informative announcements can have the curious property that they become false because they are announced. The most typical example of that is ‘fact p is true and you don’t know that’, after which you know that p, which entails the negation of the announcement formula. The announcement of such a formula in a given (...)
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  4. Editors’ Review and Introduction: Lying in Logic, Language, and Cognition.Hans Ditmarsch, Petra Hendriks & Rineke Verbrugge - 2020 - Topics in Cognitive Science 12 (2):466-484.
    Editors van Ditmarsch, Hendriks and Verbrugge of this special issue of topiCS on lying describe some recent trends in research on lying from a multidisciplinary perspective, including logic, philosophy, linguistics, psychology, cognitive science, behavioral economics, and artificial intelligence. Furthermore, they outline the seven contributions to this special issue.
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  5.  25
    Introspective forgetting.Hans Ditmarsch, Andreas Herzig, Jérôme Lang & Pierre Marquis - 2009 - Synthese 169 (2):405-423.
    We model the forgetting of propositional variables in a modal logical context where agents become ignorant and are aware of each others’ or their own resulting ignorance. The resulting logic is sound and complete. It can be compared to variable-forgetting as abstraction from information, wherein agents become unaware of certain variables: by employing elementary results for bisimulation, it follows that beliefs not involving the forgotten atom(s) remain true.
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  6.  17
    Dynamics of lying.Hans Ditmarsch - 2014 - Synthese 191 (5):745-777.
    We propose a dynamic logic of lying, wherein a ‘lie that $$\varphi $$ ’ is an action in the sense of dynamic modal logic, that is interpreted as a state transformer relative to the formula $$\varphi $$. The states that are being transformed are pointed Kripke models encoding the uncertainty of agents about their beliefs. Lies can be about factual propositions but also about modal formulas, such as the beliefs of other agents or the belief consequences of the lies of (...)
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  7.  18
    Announcement as effort on topological spaces.Aybüke Özgün, Sophia Knight & Hans Ditmarsch - 2019 - Synthese 196 (7):2927-2969.
    We propose a multi-agent logic of knowledge, public announcements and arbitrary announcements, interpreted on topological spaces in the style of subset space semantics. The arbitrary announcement modality functions similarly to the effort modality in subset space logics, however, it comes with intuitive and semantic differences. We provide axiomatizations for three logics based on this setting, with S5 knowledge modality, and demonstrate their completeness. We moreover consider the weaker axiomatizations of three logics with S4 type of knowledge and prove soundness and (...)
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  8.  38
    The Secret of My Success.Barteld Kooi & Hans Ditmarsch - 2006 - Synthese 153 (2):339-339.
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  9.  26
    Bisimulation and expressivity for conditional belief, degrees of belief, and safe belief.Martin Jensen, Hans Ditmarsch, Thomas Bolander & Mikkel Andersen - 2017 - Synthese 194 (7):2447-2487.
    Plausibility models are Kripke models that agents use to reason about knowledge and belief, both of themselves and of each other. Such models are used to interpret the notions of conditional belief, degrees of belief, and safe belief. The logic of conditional belief contains that modality and also the knowledge modality, and similarly for the logic of degrees of belief and the logic of safe belief. With respect to these logics, plausibility models may contain too much information. A proper notion (...)
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  10.  22
    A Separation Logic with Histories of Epistemic Actions as Resources.Hans van Ditmarsch, Didier Galmiche & Marta Gawek - 2023 - In Helle Hvid Hansen, Andre Scedrov & Ruy J. G. B. De Queiroz (eds.), Logic, Language, Information, and Computation: 29th International Workshop, WoLLIC 2023, Halifax, NS, Canada, July 11–14, 2023, Proceedings. Springer Nature Switzerland. pp. 161-177.
    We propose a separation logic where resources are histories (sequences) of epistemic actions so that resource update means concatenation of histories and resource decomposition means splitting of histories. This separation logic, called AMHSL, allows us to reason about the past: does what is true now depend on what was true in the past, before certain actions were executed? We show that the multiplicative connectives can be eliminated from a logical language with also epistemic and action model modalities, if the horizon (...)
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  11.  21
    Logic of change, change of logic.Hans Ditmarsch, Brian Hill & Ondrej Majer - 2009 - Synthese 171 (2):227-234.
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  12.  75
    My Beliefs about Your Beliefs: A Case Study in Theory of Mind and Epistemic Logic.Hans Van Ditmarsch & Willem Labuschagne - 2007 - Synthese 155 (2):191 - 209.
    We model three examples of beliefs that agents may have about other agents' beliefs, and provide motivation for this conceptualization from the theory of mind literature. We assume a modal logical framework for modelling degrees of belief by partially ordered preference relations. In this setting, we describe that agents believe that other agents do not distinguish among their beliefs ('no preferences'), that agents believe that the beliefs of other agents are in part as their own ('my preferences'), and the special (...)
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  13.  15
    Correction to: Dynamics of lying.Hans Ditmarsch - 2019 - Synthese 196 (6):2543-2543.
    The original publication of the article is missing the funding information.
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  14.  22
    Comments to ‘logics of public communications’.Hans Ditmarsch - 2007 - Synthese 158 (2):181-187.
    Take your average publication on the dynamics of knowledge. In one of its first paragraphs you will probably encounter a phrase like “a logic of public announcements was first proposed by Plaza in 1989 (Plaza 1989).” Tracking down this publication seems easy, because googling its title ‘Logics of Public Communications’ takes you straight to Jan Plaza’s website where it is online available in the author’s own version, including, on that page, very helpful and full bibliographic references to the proceedings in (...)
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  15.  36
    Logic in India—Editorial Introduction.Hans Ditmarsch, Rohit Parikh & R. Ramanujam - 2011 - Journal of Philosophical Logic 40 (5):557-561.
  16.  15
    Special Issue on the Occasion of Johan van Benthem’s 60th Birthday—Editorial.Hans Ditmarsch & Lawrence Moss - 2009 - Journal of Philosophical Logic 38 (6):587-588.
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  17.  16
    The Logic of Pit.Hans Ditmarsch - 2006 - Synthese 149 (2):343-374.
    Pit is a multi-player card game that simulates the commodities trading market, and where actions consist of bidding and of swapping cards. We present a formal description of the knowledge and change of knowledge in that game. The description is in a standard language for dynamic epistemics expanded with assignment. Assignment is necessary to describe that cards change hands. The formal description is a prerequisite to model Pit in game theory. The main contribution of this paper should be seen as (...)
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  18.  22
    A Theoria Round Table on Philosophy Publishing.Bengt Hansson, Hans Ditmarsch, Pascal Engel, Sven Hansson & Vincent Hendricks - 2011 - Theoria 77 (2):104-116.
    As part of the conference commemorating Theoria's 75th anniversary, a round table discussion on philosophy publishing was held in Bergendal, Sollentuna, Sweden, on 1 October 2010. Bengt Hansson was the chair, and the other participants were eight editors‐in‐chief of philosophy journals: Hans van Ditmarsch (Journal of Philosophical Logic), Pascal Engel (Dialectica), Sven Ove Hansson (Theoria), Vincent Hendricks (Synthese), Søren Holm (Journal of Medical Ethics), Pauline Jacobson (Linguistics and Philosophy), Anthonie Meijers (Philosophical Explorations), Henry S. Richardson (Ethics) and Hans Rott (Erkenntnis).
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  19.  23
    Reasoning about local properties in modal logic.Wiebe van der Hoek, Hans van Ditmarsch & Barteld Kooi - unknown
    Hans van Ditmarsch, Wiebe van der Hoek and Barteld Kooi (2011). Reasoning about local properties in modal logic. In K. Tumer and P. Yolum and L. Sonenberg and P. Stone (editors). Proceedings of the 10th International Conference on Autonomous Agents and Multiagent Systems (AAMAS 2011), pp. 711-718.
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  20. Playing Cards with Hintikka: An Introduction to Dynamic Epistemic Logic.Barteld Kooi, Wiebe Hoek & Hans Ditmarsch - 2018 - In Hans van Ditmarsch & Gabriel Sandu (eds.), Jaakko Hintikka on Knowledge and Game Theoretical Semantics. Cham, Switzerland: Springer.
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  21.  14
    Playing Cards with Hintikka: An Introduction to Dynamic Epistemic Logic.Barteld Kooi, Wiebe Hoek & Hans Ditmarsch - 2018 - In Hans van Ditmarsch & Gabriel Sandu (eds.), Jaakko Hintikka on Knowledge and Game Theoretical Semantics. Cham, Switzerland: Springer. pp. 237-262.
    This contribution is a gentle introduction to so-called dynamic epistemic logics, that can describe how agents change their knowledge and beliefs. We start with a concise introduction to epistemic logic, through the example of one, two and finally three players holding cards; and, mainly for the purpose of motivating the dynamics, we also very summarily introduce the concepts of general and common knowledge. We then pay ample attention to the logic of public announcements, wherein agents change their knowledge as the (...)
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  22.  18
    Private Announcements on Topological Spaces.Aybüke Özgün, Sophia Knight & Hans Ditmarsch - 2018 - Studia Logica 106 (3):481-513.
    In this work, we present a multi-agent logic of knowledge and change of knowledge interpreted on topological structures. Our dynamics are of the so-called semi-private character where a group G of agents is informed of some piece of information $$\varphi $$ φ, while all the other agents observe that group G is informed, but are uncertain whether the information provided is $$\varphi $$ φ or $$\lnot \varphi $$ ¬φ. This article follows up on our prior work where the dynamics were (...)
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  23.  34
    Johan van Benthem, Modal Logic for Open Minds, CSLI Lecture Notes, Stanford University, 2010, pp. 350. ISBN: 9781575865997 (hardcover) US $70.00, ISBN: 9781575865980 (paperback) US $30.00. [REVIEW]Hans Ditmarsch - 2012 - Studia Logica 100 (5):1055-1057.
  24. Review. [REVIEW]Hans Ditmarsch - 2010 - Theoria 76 (3):270-273.
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