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)

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)

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)

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)

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)

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)

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)

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)

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)

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 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)

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)

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)

This paper demonstrates the undecidability of a number of logics with quantification over public announcements: arbitrary public announcement logic, group announcement logic, and coalition announcement logic. In APAL we consider the informative consequences of any announcement, in GAL we consider the informative consequences of a group of agents all of which are simultaneously making known announcements. So this is more restrictive than APAL. Finally, CAL is as GAL except that we now quantify over anything the agents (...) not in that group may announce simultaneously as well. The logic CAL therefore has some features of game logic and of ATL. We show that when there are multiple agents in the language, the satisfiability problem is undecidable for APAL, GAL, and CAL. In the single agent case, the satisfiability problem is decidable for all three logics. (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)

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.

In the early 1990s, at the New York Harmony Theater, Annie Sprinkle presented her most famous performance, A Public Cervix Announcement, during which she invited the public to observe her cervix. This performance promoted a feminist re-appropriation of the female genitals and the subversion of andro- and heterocentred codes of pornographic imagery. It is often seen as an extension of pro-sex feminism and as a cornerstone of post-porn. This article aims to show how the images of sexuality staged in (...) this performance, in the wake of pro-sex and post-porn approaches, sought to elaborate new ways of showing minorized bodies and sexualities. (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)