Constraints on extensions of a default theory

2001 ◽  
Vol 16 (4) ◽  
pp. 329-340 ◽  
Author(s):  
Kaile Su
Keyword(s):  
Default Theory

Servicers and Mortgage-Backed Securities Default: Theory and Evidence

2010 ◽  
Author(s):  
Brent W. Ambrose ◽  
Anthony B. Sanders ◽  
Abdullah Yavas
Keyword(s):  
Default Theory ◽  
Mortgage Backed Securities

scholarly journals More on Modal Aspects of Default Logic1

1992 ◽  
Vol 17 (1-2) ◽  
pp. 99-116
Author(s):  
V. Wiktor Marek ◽  
Miroslaw Truszczynski
Keyword(s):  
Modal Logic ◽  
Default Logic ◽  
Nonmonotonic Logic ◽  
Default Reasoning ◽  
Default Theory ◽  
Autoepistemic Logic ◽  
The Relationship ◽  
Natural Classes ◽  
Weak Extension

Investigations of default logic have been so far mostly concerned with the notion of an extension of a default theory. It turns out, however, that default logic is much richer. Namely, there are other natural classes of objects that might be associated with default reasoning. We study two such classes of objects with emphasis on their relations with modal nonmonotonic formalisms. First, we introduce the concept of a weak extension and study its properties. It has long been suspected that there are close connections between default and autoepistemic logics. The notion of weak extension allows us to precisely describe the relationship between these two formalisms. In particular, we show that default logic with weak extensions is essentially equivalent to autoepistemic logic, that is, nonmonotonic logic KD45. In the paper we also study the notion of a set of formulas closed under a default theory. These objects are shown to correspond to stable theories and to modal logic S5. In particular, we show that skeptical reasoning with sets closed under default theories is closely related with provability in S5. As an application of our results we determine the complexity of reasoning with weak extensions and sets closed under default theories.

Why Won’t You Answer the Question? Mass-Mediated Deception Detection After Journalists’ Accusations of Politicians’ Evasion

2019 ◽  
Vol 69 (6) ◽  
pp. 674-695
Author(s):  
David E Clementson
Keyword(s):  
Process Modeling ◽  
Deception Detection ◽  
Multiple Mediation ◽  
Default Theory ◽  
Default State ◽  
The Media

Abstract Journalists often accuse politicians of dodging questions. Truth-default theory (TDT) predicts that when journalists serve as de facto deception detectors, the audience will process the messaging through a cognitive sequence that lowers the perceived trustworthiness of the politician. Conversely, the public’s perception of the media as being generally hostile and biased in their reporting could make a journalist’s allegation of evasion enhance the politician’s credibility. We constructed political TV interviews in which a journalist falsely accused a politician of evasiveness. Consistent with serial multiple mediation as proposed by TDT, in Study 1 (N = 210 U.S. voters) a journalist’s allegation triggered suspicion, which increased perceived dodging, resulting in voters distrusting the politician. Absent a journalist’s allegation, however, people remained in their truth-default state toward the politician. Study 2 (N = 429) replicated the Study 1 results, and conditional process modeling revealed that the effect was moderated by rumination.

scholarly journals Sequent-Type Calculi for Three-Valued and Disjunctive Default Logic

Axioms ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 84 ◽  
Author(s):  
Sopo Pkhakadze ◽  
Hans Tompits
Keyword(s):  
Proof Theory ◽  
Consistency Condition ◽  
Nonmonotonic Reasoning ◽  
Default Logic ◽  
Inference Process ◽  
Default Theory ◽  
Valid Inference ◽  
The One ◽  
Base Logic ◽  
Selection Of

Default logic is one of the basic formalisms for nonmonotonic reasoning, a well-established area from logic-based artificial intelligence dealing with the representation of rational conclusions, which are characterised by the feature that the inference process may require to retract prior conclusions given additional premisses. This nonmonotonic aspect is in contrast to valid inference relations, which are monotonic. Although nonmonotonic reasoning has been extensively studied in the literature, only few works exist dealing with a proper proof theory for specific logics. In this paper, we introduce sequent-type calculi for two variants of default logic, viz., on the one hand, for three-valued default logic due to Radzikowska, and on the other hand, for disjunctive default logic, due to Gelfond, Lifschitz, Przymusinska, and Truszczyński. The first variant of default logic employs Łukasiewicz’s three-valued logic as the underlying base logic and the second variant generalises defaults by allowing a selection of consequents in defaults. Both versions have been introduced to address certain representational shortcomings of standard default logic. The calculi we introduce axiomatise brave reasoning for these versions of default logic, which is the task of determining whether a given formula is contained in some extension of a given default theory. Our approach follows the sequent method first introduced in the context of nonmonotonic reasoning by Bonatti, which employs a rejection calculus for axiomatising invalid formulas, taking care of expressing the consistency condition of defaults.

Credibility Perceptions and Detection Accuracy of Fake News Headlines on Social Media: Effects of Truth-Bias and Endorsement Cues

2020 ◽  
pp. 009365022092132
Author(s):  
Mufan Luo ◽  
Jeffrey T. Hancock ◽  
David M. Markowitz
Keyword(s):  
Social Media ◽  
Deception Detection ◽  
Detection Accuracy ◽  
Fake News ◽  
Default Theory ◽  
Impact Detection ◽  
Truth Bias ◽  
News Credibility ◽  
Biased Processing ◽  
News Headlines

This article focuses on message credibility and detection accuracy of fake and real news as represented on social media. We developed a deception detection paradigm for news headlines and conducted two online experiments to examine the extent to which people (1) perceive news headlines as credible, and (2) accurately distinguish fake and real news across three general topics (i.e., politics, science, and health). Both studies revealed that people often judged news headlines as fake, suggesting a deception-bias for news in social media. Across studies, we observed an average detection accuracy of approximately 51%, a level consistent with most research using this deception detection paradigm with equal lie-truth base-rates. Study 2 evaluated the effects of endorsement cues in social media (e.g., Facebook likes) on message credibility and detection accuracy. Results showed that headlines associated with a high number of Facebook likes increased credibility, thereby enhancing detection accuracy for real news but undermining accuracy for fake news. These studies introduce truth-default theory to the context of news credibility and advance our understanding of how biased processing of news information can impact detection accuracy with social media endorsement cues.

Servicers and Mortgage-Backed Securities Default: Theory and Evidence

2015 ◽  
Vol 44 (2) ◽  
pp. 462-489 ◽  
Author(s):  
Brent W. Ambrose ◽  
Anthony B. Sanders ◽  
Abdullah Yavas
Keyword(s):  
Default Theory ◽  
Mortgage Backed Securities

scholarly journals Critique of the Classical Theory of Education Crisis

2021 ◽  
Vol 29 (3) ◽  
pp. 19-67
Author(s):  
Glenn Rikowski
Keyword(s):  
Classical Theory ◽  
Second World War ◽  
Contemporary Society ◽  
World War ◽  
Economic Crises ◽  
Default Theory ◽  
Theory Of Education ◽  
Education Crisis ◽  
Second World

The Classical Theory of Education Crisis is the default theory utilised by educational theorists for understanding the constitution and explanation of education crises in contemporary society. Following a brief outline of the concept of crisis, and the histiography of the notion of education crisis from the Second World War to the neoliberal recession of 1980-82, there is an outline of The Classical Theory of Education Crisis as most fully expressed in Madan Sarup’s classic Education, State and Crisis: A Marxist Perspective (1982). The key aspect of the Classical Theory is that education crises are derivative of economic crises. This is followed by the main event: critique of the Classical Theory. Its reliance on structuralist thought (with associated determinism, functionalism and reductionism) and the inflow of economics imperialism are some of its key deficiencies. The Conclusion outlines ground still to be covered and the need to move beyond the Classical Theory of Education Crisis.

Reasoning about Actions in Prioritized Default Theory

2002 ◽  
pp. 369-381 ◽  
Author(s):  
Tran Cao Son ◽  
Enrico Pontelli
Keyword(s):  
Default Theory ◽  
Reasoning About Actions
Sign in / Sign up

Export Citation Format

Share Document