While dynamic epistemic logics with common knowledge have been extensively studied, dynamic epistemic logics with distributed knowledge have so far received far less attention. In this paper we study extensions of public announcement logic ( $\mathcal{PAL }$ ) with distributed knowledge, in particular their expressivity, axiomatisations and complexity. $\mathcal{PAL }$ extended only with distributed knowledge is not more expressive than standard epistemic logic with distributed knowledge. Our focus is therefore on $\mathcal{PACD }$ , the result of adding both common (...) and distributed knowledge to $\mathcal{PAL }$ , which is more expressive than each of its component logics. We introduce an axiomatisation of $\mathcal{PACD }$ , which is not surprising: it is the combination of well-known axioms. The completeness proof, however, is not trivial, and requires novel combinations and extensions of techniques for dealing with $S5$ knowledge, distributed knowledge, common knowledge and public announcements at the same time. We furthermore show that $\mathcal{PACD }$ is decidable, more precisely that it is $\textsc {exptime}$ -complete. This result also carries over to $\mathcal{S 5\mathcal CD }$ with common and distributed knowledge operators for all coalitions (and not only the grand coalition). Finally, we propose a notion of a trans-bisimulation to generalise certain results and give deeper insight into the proofs. (shrink)

In the literature, different axiomatizations of Public Announcement Logic (PAL) have been proposed. Most of these axiomatizations share a “core set” of the so-called “reduction axioms”. In this paper, by designing non-standard Kripke semantics for the language of PAL, we show that the proof system based on this core set of axioms does not completely axiomatize PAL without additional axioms and rules. In fact, many of the intuitive axioms and rules we took for granted could not be derived from (...) the core set. Moreover, we also propose and advocate an alternative yet meaningful axiomatization of PAL without the reduction axioms. The completeness is proved directly by a detour method using the canonical model where announcements are treated as merely labels for modalities as in normal modal logics. This new axiomatization and its completeness proof may sharpen our understanding of PAL and can be adapted to other dynamic epistemic logics. (shrink)

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 completeness results for these systems. (shrink)

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 completeness results for these systems. (shrink)

Each year the JHP awards an Article Prize to an article published in the previous year's volume, and a Book Prize to a book published in the previous year that deserves special recognition for its contribution to the history of Western philosophy. For the Book Prize, publishers may nominate books by submitting a hard copy to the Book Review Editor for consideration. The nomination and book must be received by January 1 following the year for which the prize is to (...) be awarded.The JHP Board of Directors awards an annual prize of $5,000 for the best book in the history of philosophy published in the previous year. On the Board's behalf, I am pleased to announce that the... (shrink)

Arbitrary public announcement logic ) reasons about how the knowledge of a set of agents changes after true public announcements and after arbitrary announcements of true epistemic formulas. We consider a variant of arbitrary public announcement logic called positive arbitrary public announcement logic ), which restricts arbitrary public announcements to announcement of positive formulas. Positive formulas prohibit statements about the ignorance of agents. The positive formulas correspond to the universal fragment in first-order logic. As two successive (...) announcements of positive formulas need not correspond to the announcement of a positive formula, \ is rather different from \. We show that \ is more expressive than public announcement logic \, and that \ is incomparable with \. We also provide a sound and complete infinitary axiomatisation. (shrink)

The paper gives a formal analysis of public lies, explains how public lying is related to public announcement, and describes the process of recoveries from false beliefs engendered by public lying. The framework treats two kinds of public lies: simple lying update and two-step lying, which consists of suggesting that the lie may be true followed by announcing the lie. It turns out that agents’ convictions of what is true are immune to the first kind, but can be shattered (...) by the second kind. Next, recovery from public lying is analyzed. Public lies that are accepted by an audience cannot be undone simply by announcing their negation. The paper proposes a recovery process that works well for restoring beliefs about facts but cannot be extended to beliefs about beliefs. The formal machinery of the paper consists of KD45 models and conditional neighbourhood models, with various update procedures on them. Completeness proofs for a number of reasoning systems (converse belief logic, public lies logic, lying and recovery logic, conditional neighbourhood logic, plus its dynamic version) are included. (shrink)

In Part I of this paper we presented a Hilbert-style system $\Sigma _D$ axiomatizing stit logic of justification announcements interpreted over models with discrete time structure. In this part, we prove three frame definability results for $\Sigma _D$ using three different definitions of a frame plus another version of completeness result.

This article investigates the announced refusal to answer as a form of dispreferred and challenging response in broadcast political interviews. The aim is to study how the rightness and wrongness of conduct is dealt with in situations of announced refusal. More specifically, the paper focuses on: announced refusal as a particular type of conduct; the orientation to norms and accountability in situations of announced refusal; how the legitimacy of politics and journalism is negotiated in broadcast interviews. The data consist of (...) 23 cases from Swedish election campaigns, and the analysis is based on Conversation Analysis, focusing on how the participants treat themselves and others as normatively accountable. The study indicates that the politicians understand themselves as accountable and avoid hostile actions in the interviews. Their refusals are designed mainly to be understood as appropriate distancing actions without explicitly complaining about the interviewers’ conduct. (shrink)

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 \, while all the other agents observe that group G is informed, but are uncertain whether the information provided is \ or \. This article follows up on our prior work where the dynamics were public events. We provide a complete axiomatization (...) of our logic, and give two detailed examples of situations with agents learning information through semi-private announcements. (shrink)

Prior stock repurchase studies have found evidence that the announcement of a repurchase program sends a positive signal to the market. Firms engaging in open-market repurchase programs do not have to report how, when, and if they actually repurchased any shares. Evidence following the stock market crash of 1987 indicates that many firms announcing repurchase plans did not actually repurchase any share and, by their own admission, had no intention of repurchasing shares. Companies announcing plans and not following through (...) are apparently within the letter of the law. However, we argue that companies announcing plans with no intention of repurchasing shares are guilty of either lying or sending false signals. These companies create distrust in the investment community and intentionally mislead the public in violation of the SEC's antifraud provisions. Changes in the reporting procedures concerning repurchase plans are ethically and legally warranted. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Editorial AnnouncementGerald A. PressIt is my pleasure to announce that Jan Wojcik of Auburn University is the new Book Review Editor of the Journal of the History of Philosophy. All correspondence concerning book reviews should be directed to Professor Wojcik in Alabama effective immediately. The mailing address is: Prof. Jan Wojcik, Journal of the History of Philosophy, Department of Philosophy, Auburn University, AL 36849-5210. E-mail: [email protected] thank the former (...) Book Review Editor, Manfred Kuehn, for his service to this Journal.Copyright © 2000 Journal of the History of Philosophy, Inc.... (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Philosophy and Rhetoric 33.1 (2000) v [Access article in PDF] Editorial Announcement The editors wish to announce the departure of Pierre Kerszberg, who has joined the Departement de Philosophie, Universite de Toulouse-Le Mirail. We wish him the very best and are grateful for his editorial services. We are pleased to announce the appointment of Professor Richard A. Lee Jr., a specialist in the history of philosophy, as co-editor (...) of Philosophy and Rhetoric.Stephen H. Browne... (shrink)

We formalize what it means to have permission to say something. We adapt the dynamic logic of permission by van der Meyden (J Log Comput 6(3):465–479, 1996 ) to the case where atomic actions are public truthful announcements. We also add a notion of obligation. Our logic is an extension of the logic of public announcements introduced by Plaza ( 1989 ) with dynamic modal operators for permission and for obligation. We axiomatize the logic and show that it is decidable.

Ricoeur’s hermeneutics provides us with an important and original account of the meaning and the implications of the “ontological turn” that has taken place in hermeneutics since Heidegger’s work. By means of the pair ontologisation and hermeneutisation, which is borrowed from Jean Grondin, this paper examineshow Ricoeur rethinks the relation between being and language. Distancing itself from Nancy’s critique of Ricoeur’s hermeneutics, this paper first shows thatRicoeur’s hermeneutic ontology should not be understood as a “secondary” form of hermeneutics. Rather, it (...) provides us with a critical revision of Heidegger’s “primordial” hermeneutics that is centered on the notion of announcement. Secondly, it shows how, by this revision, Ricoeur does not only develop an alternative to Heidegger’s accounts of announcement and attestation, but also to Derrida’s account of equivocity. (shrink)

This paper investigates the stock market reaction to the announcement that a firm has been included in the UK FTSE4Good index of socially responsible firms. We use the announcement of firm inclusion in the index to estimate the stock market reaction to a firm being classified as socially responsible. This is an important test of whether investors view the undertaking of socially responsible activities by firms as a value increasing or value decreasing initiative by management. We do not (...) find strong evidence in favour of a positive market reaction. However, there is a large cross-sectional variation in the market reaction to this announcement. Investors appear to be reacting to this event and there are a number of firm characteristics that are well-established proxies for CSR that can explain the market reaction. (shrink)

New energy vehicle policies have greatly promoted the growth of the NEV industry in China, while also attracting a lot of investor attention. Using Chinese NEV concept stocks and related industrial policies, including purchase tax incentives and promotion and application policies, issued from 2011 to 2020 as the research setting, this paper adopts a panel data model to examine the impact of policy announcement on the volatility of NEV concept stocks, as well as the mediating role of investor attention (...) in transmitting the impact. We find that NEV P&A policies have a significant and positive impact on NEV concept stock volatility, while PTI policies do not have a significant impact. Moreover, investor attention plays a partial mediating role in transmitting the impact of P&A policies on NEV stock market by increasing the stock volatility risk. Furthermore, there is heterogeneous effect of equity ownership in the relationship between policy announcement and investor attention on the volatility of NEV concept stocks; non-state-owned firms are more sensitive to the NEV P&A policies than state-owned firms. By analyzing the relationship between policy announcement and concept stock volatility, this paper enriches the research on NEV concept stocks and provides policy implications for the NEV industry. (shrink)

We study the extension of public announcement logic PAL by public assignments, which we call PALA. Just as in the case of PAL, the standard procedure for deciding PALA validity, i.e. the use of so-called reduction axioms to translate PALA formulae into formulae in epistemic logic EL, may lead to exponential growth. In this paper, we show that such a price is not mandatory, for we provide a polynomial translation of PALA into EL. This is based on abbreviations of (...) subformulae by new propositional letters. Such optimal translation also enables us to show the computational complexity of the problem of deciding PALA validity, which turns out to be coNP-complete in the single-agent case and PSPACE-complete in the multiagent case. (shrink)

Extending the work of Davidson and Worrell, we further investigate the stock market''s reaction to announced corporate illegalities. We examine a sample of 535 announcements of corporate crime and obtain an overall insignificant stock market reaction. However, when the sample is divided by type of crime, we find that the stock market reacts significantly to announcements of bribery, tax evasion, and violations of government contracts. We also find a significantly negative reaction to announcements of corporate crime when the company had (...) been previously accused of other illegal activity. For companies accused of crime in the 1970s, 51% of them were accused again in the 1980s. (shrink)

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 (...) public events. We provide a complete axiomatization of our logic, and give two detailed examples of situations with agents learning information through semi-private announcements. (shrink)

Public announcement logic is an extension of epistemic logic with dynamic operators that model the effects of all agents simultaneously and publicly acquiring the same piece of information. One of the extensions of PAL, group announcement logic, allows quantification over announcements made by agents. In GAL, it is possible to reason about what groups can achieve by making such announcements. It seems intuitive that this notion of coalitional ability should be closely related to the notion of distributed knowledge, (...) the implicit knowledge of a group. Thus, we study the extension of GAL with distributed knowledge, and in particular possible interaction properties between GAL operators and distributed knowledge. The perhaps surprising result is that, in fact, there are no interaction properties, contrary to intuition. We make this claim precise by providing a sound and complete axiomatisation of GAL with distributed knowledge. We also consider several natural variants of GAL with distributed knowledge, as well as some other related logic, and compare their expressive power. (shrink)