Default Logic Research Articles

A Tractable First-Order Probabilistic Logic

Tractable subsets of first-order logic are a central topic in AI research. Several of these formalisms have been used as the basis for first-order probabilistic languages. However, these are intractable, losing the original motivation. Here we propose the first non-trivially tractable first-order probabilistic language. It is a subset of Markov logic, and uses probabilistic class and part hierarchies to control complexity. We call it TML (Tractable Markov Logic). We show that TML knowledge bases allow for efficient inference even when the corresponding graphical models have very high treewidth. We also show how probabilistic inheritance, default reasoning, and other inference patterns can be carried out in TML. TML opens up the prospect of efficient large-scale first-order probabilistic inference.

Two dogmas of aesthetic empiricism

AbstractAesthetic hedonism is the default theory of aesthetic value. Some of its critics share with it a pair of unquestioned assumptions, namely, that any theory of aesthetic value should make special appeal to its being the case that the canonical form of aesthetic evaluation is a state of pleasure and to its being the case that the canonical purpose of aesthetic acts is to access pleasure. This paper argues that there is reason to doubt both assumptions. Doubting both assumptions suggests a wider range of alternatives to aesthetic hedonism and primitivist inversions of aesthetic hedonism.

Customizing the following behavior models to mimic the weak lane based mixed traffic conditions

This study aims to model traffic flow under weak lane based heterogonous (mixed) traffic conditions. Unlike homogeneous traffic, when a follower (subject) vehicle in mixed traffic moves closer to its leader vehicle, it tends to adjust its longitudinal movement or change its lane and acts discretely. Due to this phenomenon, traffic flow modeling under such conditions is always challenging. A new driver behavioral logic is conceptualized for the vehicles’ movement within a combination of surrounding vehicles. In which the following behavior was dissected with the lateral shift distance between vehicles. Two car-following models for homogeneous traffic conditions, the IDM and Gipps models were adapted with relevant lateral behavior parameters to different vehicle classes under mixed-traffic conditions. The new driving behavior logic was incorporated externally in place of default logic. The results showed that the performance of the adapted models was better accurate than the classical models.

Structured argumentation dynamics

This paper develops a logical theory that unifies all three standard types of argumentative attack in AI, namely rebutting, undercutting and undermining attacks. We build on default justification logic that already represents undercutting and rebutting attacks, and we add undermining attacks. Intuitively, undermining does not target default inference, as undercutting, or default conclusion, as rebutting, but rather attacks an argument’s premise as a starting point for default reasoning. In default justification logic, reasoning starts from a set of premises, which is then extended by conclusions that hold by default. We argue that modeling undermining defeaters in the view of default theories requires changing the set of premises upon receiving new information. To model changes to premises, we give a dynamic aspect to default justification logic by using the techniques from the logic of belief revision. More specifically, undermining is modeled with belief revision operations that include contracting a set of premises, that is, removing some information from it. The novel combination of default reasoning and belief revision in justification logic enriches both approaches to reasoning under uncertainty. By the end of the paper, we show some important aspects of defeasible argumentation in which our logic compares favorably to structured argumentation frameworks.

Clinico-histopathological Profile of Primary Paediatric Intra-abdominal Tumours: a Multi-hospital-Based Study.

The online version contains supplementary material available at 10.1007/s13193-021-01365-x.

Metacognitive asymmetries in visual perception.

Representing the absence of objects is psychologically demanding. People are slower, less confident and show lower metacognitive sensitivity (the alignment between subjective confidence and objective accuracy) when reporting the absence compared with presence of visual stimuli. However, what counts as a stimulus absence remains only loosely defined. In this Registered Report, we ask whether such processing asymmetries extend beyond the absence of whole objects to absences defined by stimulus features or expectation violations. Our pre-registered prediction was that differences in the processing of presence and absence reflect a default mode of reasoning: we assume an absence unless evidence is available to the contrary. We predicted asymmetries in response time, confidence, and metacognitive sensitivity in discriminating between stimulus categories that vary in the presence or absence of a distinguishing feature, or in their compliance with an expected default state. Using six pairs of stimuli in six experiments, we find evidence that the absence of local and global stimulus features gives rise to slower, less confident responses, similar to absences of entire stimuli. Contrary to our hypothesis, however, the presence or absence of a local feature has no effect on metacognitive sensitivity. Our results weigh against a proposal of a link between the detection metacognitive asymmetry and default reasoning, and are instead consistent with a low-level visual origin of metacognitive asymmetries for presence and absence.

Research on listed companies’ credit ratings, considering classification performance and interpretability

Any credit evaluation system must be able not only to identify defaults, but also to be interpretable and provide reasons for defaults. Therefore, this study uses the correlation coefficient and F-test to select the initial features of a credit evaluation system, and then a validity index for a second selection to ensure that the feature system has the optimum ability to discriminate in determining default status. We omit one feature in each iteration by replacing each feature, calculating the changes in validity index values after deleting this feature and, finally, calculating the ratio of the change value to the sum of all change values. This ratio is then used as the feature’s weight. This study also introduces a data gravity model in predicting defaults, as predicting a validation set’s default status derives the classification threshold to maximize classification accuracy. An empirical analysis of the listed company samples reveals that the feature system selected from 610 features can distinguish between both defaults and nondefaults. Compared with eight other models, our data gravity model not only exhibits good classification performance, but also has interpretability; further, this model can provide at least five-year-ahead forecasting, and can offer a timely risk warning for banks.

Critique of the Classical Theory of Education Crisis

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.

Factors Affecting Neonatal Hearing Screening Follow-up in Developing Countries: One Insitution Prospective Pilot Study.

ObjectiveTo detect factors related with loss to follow-up (LTF) in neonatal hearing screening (NHS) program of one institution in a developing country.MethodsA prospective study was planned based on the data collected in a pilot study conducted a year before in the same institution. In this pilot study, hearing screening was performed before hospital discharge for every infant (1217 newborns) in six months period. Total referral rate was 19.1% (223/1217). Loss to follow-up (LTF) was 38.1% (85/223). Telephonic interviews were done with 50 parents who had not come with their child to the second hearing test. For these telephonic interviews the questionnaire with four sections (socio-demographic information; information about pregnancy, birth, and present health condition of the child; caregiver knowledge of neonatal hearing screening, and reasons for default on follow-up) was created.ResultsThe mothers participated in this study were 29.1 years (±5.2 SD) of age in average. Place of residence was mostly rural (64%; n=32) with 39.4 Km (±24.8 SD) away from from the rescreen referral center. Their knowledge on neonatal hearing screening, hearing impairment incidence or treatment opportunities was at a very low level. Caregivers’ perceptions that follow-up was unnecessary (50%; n=25), was most frequently given reason for follow-up default, followed by newborns bad health condition (12%; n=6) and forgetting about the follow-up visits (8%; n=6).ConclusionThe main reason for default in follow-up in our study was caregiver’s poor knowledge about this topic.

A logic of defeasible argumentation: Constructing arguments in justification logic

In the 1980s, Pollock’s work on default reasons started the quest in the AI community for a formal system of defeasible argumentation. The main goal of this paper is to provide a logic of structured defeasible arguments using the language of justification logic. In this logic, we introduce defeasible justification assertions of the type t : F that read as “t is a defeasible reason that justifies F”. Such formulas are then interpreted as arguments and their acceptance semantics is given in analogy to Dung’s abstract argumentation framework semantics. We show that a large subclass of Dung’s frameworks that we call “warranted” frameworks is a special case of our logic in the sense that (1) Dung’s frameworks can be obtained from justification logic-based theories by focusing on a single aspect of attacks among justification logic arguments and (2) Dung’s warranted frameworks always have multiple justification logic instantiations called “realizations”. We first define a new justification logic that relies on operational semantics for default logic. One of the key features that is absent in standard justification logics is the possibility to weigh different epistemic reasons or pieces of evidence that might conflict with one another. To amend this, we develop a semantics for “defeaters”: conflicting reasons forming a basis to doubt the original conclusion or to believe an opposite statement. This enables us to formalize non-monotonic justifications that prompt extension revision already for normal default theories. Then we present our logic as a system for abstract argumentation with structured arguments. The format of conflicting reasons overlaps with the idea of attacks between arguments to the extent that it is possible to define all the standard notions of argumentation framework extensions. Using the definitions of extensions, we establish formal correspondence between Dung’s original argumentation semantics and our operational semantics for default theories. One of the results shows that the notorious attack cycles from abstract argumentation cannot always be realized as justification logic default theories.

Пути трансформации метафизического мышления в «беспонятийном языке» позднего М. Хайдеггера

The article provides an analysis of the concept of “conceptless language” in the works of the late Martin Heidegger. The formation of a “conceptless language” is one of the most mysterious phenomena in the philosophy of the thinker. The specific structure of this lan­guage is one of the main criticisms of the later works of the philosopher and the opposition of Heidegger as the author of “Sein und Zeit” to Heidegger of the period “Beiträge zur Philosophie. Vom Ereignis”. The article explains the specific structure of the “concept-free language”, the reasons for its creation and its role in the late Heidegger philosophy. An at­tempt is made to reveal the hidden logic of a “conceptless language” and the principles by which it is guided. The search for the logic of a “conceptless language” is carried out through consideration of some of its aspects: a way of expressing thoughts, features of the style of argumentation, and a method of forming terms. An analysis of these aspects shows how Heidegger seeks to overcome the problem of the so-called “refusal” (Versagen) of the language that arose after writing “Sein und Zeit”. In search of a language correspond­ing to the transition to a different beginning, the principles of the late Heidegger hermeneutic methodology are formed: the “principle of intentional incomprehensibility” of terms, “default logic”, clarification of terms through their “internal form”, method of “thoughtful use of language” (besinnliche Sprachgebrauch). The analysis leads to the con­clusion that the profound change in thinking, which the late Heidegger sought on the way to another beginning, is impossible without the transformation of the language. Due to the fact that the existing “metaphysical” thinking is directly related to the conceptual lan­guage, a “non-conceptual language” opens the way for alternative thinking.

“I Feel Healthy Like Any Other Person” Reasons for Defaulting from ART Treatments Use Among Adults Living with HIV in Tunduru District: A Qualitative Inquiry

<i>Background</i>: Continuing use of ART treatments is reported to improve health and health outcomes of people living with HIV. However, adherence to ART prescriptions is generally a challenge and many people default from HIV care and treatment. This study assessed reasons for ART treatment default among adults living with HIV in Tunduru district Tanzania. <i>Methods</i>: We conducted a qualitative cross-sectional study between January and February 2018. Ten key informants who had defaulted from HIV care and treatment for five or more months were engaged in in-depth interviews on reasons behind defaulting. Thematic analysis using NVivo was conducted to identify emerging themes. <i>Results</i>: Reasons for defaulting from ART treatments which emerged include being tired of using the ART medications for a long time, not experiencing HIV related symptoms, fear of stigma and shame of being known to use ART, inadequate food, fear of side effects and use of local herbs as alternative. Other reasons include long distance to the health facilities and long waiting time for the services at the facility. <i>Conclusion</i>: Reasons for defaulting from HIV treatment and care among adults are multifaceted in nature requiring multifaceted efforts to address them if the gains intended from the use of ART are to be achieved and sustained.

Risk Management Impact on Non-Performing Loans and Profitability in the Namibian Banking Sector

The Banking sector has a pivotal role in the development of an economy. It is the key driver of economic growth of the country. Various literature revealed that non-performing loans were one of the causes of the financial crisis in 2007. The rise in non-performing loans has been taken under consideration by many banks in the world, as banks look at different methods on how to reduce non-performing loans. The following study was carried out with the objective to analyze the impact of risk management on non-performing loans in the country and identifying different strategies used around the world that assists banks in battling non-performing loans. The study used the four major commercial banks in Namibia as samples. The study analyzed two theories Agency Theory and Credit default theory. The study used only secondary data to answer the research objectives. The limitations of the study were that the study only looked at non-performing loans of credit risks the banks face. The study was not able to use all the commercial banks as samples to gather data. The strategy of the study was an archival strategy and the study used a qualitative approach. The study found that the Namibian banks experienced an increase throughout the five years in both profits and non-performing loans. The year 2018 was the non-performing loans of the banks the highest. The study concluded that even though banks have all the risk management systems in place non-performing loans are still increasing.

Default logic and bounded treewidth

In this paper, we study Reiter's propositional default logic when the treewidth of a certain graph representation (semi-primal graph) of the input theory is bounded. We establish a dynamic programming algorithm on tree decompositions that decides whether a theory has a consistent stable extension ( Cons ). Our algorithm can even be used to enumerate all generating defaults ( EnumSD ) that lead to stable extensions. We show that our algorithm decides Cons in linear time in the input theory and triple exponential time in the treewidth Further, our algorithm solves EnumSD with a pre-computation step that is linear in the input theory and triple exponential in the treewidth followed by a linear delay to output solutions. Finally, we take the exponential time hypothesis (ETH) into consideration and establish lower bounds of bounded treewidth algorithms for Cons.

Inflation, default and sovereign debt: The role of denomination and ownership

Emerging market governments hold mixed debt portfolios: They borrow at home and abroad in both nominal and real terms. This paper incorporates such a mixed debt structure into a theory of sovereign debt, default and inflation. The government optimally uses both default and inflation to balance its budget. The portfolio structure affects the relative benefits of inflation, default and incentives to accumulate debt. A calibrated version of the model can account for key features of the Mexican economy. We use the model to study if portfolio shifts away from purely real and external debt contributed to emerging market disinflation in the mid 1990s. We find that the answer depends on the distinction between ownership and denomination: Increasingly nominal debt is inflationary if held abroad, but lowers inflation if held at home.

The Double Trigger for Mortgage Default: Evidence from the Fracking Boom

This paper exploits a natural experiment afforded by the fracking boom in Pennsylvania to shed light on the determinants of mortgage default. Looking only at mortgages originated before fracking became viable, and using the underlying geology as a supply shifter, we find that mortgages on homes exposed to shale drilling experience a significant reduction in default risk. This effect is more than four times greater for borrowers who are underwater on their loans. Additional evidence shows that fracking activity does not raise house prices, but significantly increases household income through higher royalty payments, wages, and salaries. Furthermore, we find that fracking directly leads to employment increases in the drilling/mining and construction sectors at the county level and reduces income from unemployment benefits at the ZIP-code level. Finally, in addition to reducing mortgage-default risk, we show that fracking lowers credit card delinquencies. These results are most consistent with the “double-trigger” theory of mortgage default, where underwater borrowers subject to an adverse income shock are much more likely to lose their homes to foreclosure. This paper was accepted by David Simchi-Levi, finance.

Determinants of tuberculosis patients attending Directly Observed Treatment Short course (DOTS) centre for prevention of default in TB treatment

Introduction: It was necessary to understand the reasons for default after initiation of the treatment and plan strategies to reduce default and thereby increase the success of treatment outcome. Materials and Methods: The present observational cross-sectional study was carried out in selected DOTS centers of district Ghaziabad Department of Community Medicine, Santosh Medical College, Ghaziabad. All new sputum smear positive pulmonary tuberculosis patients were taking treatment from sampled DOTS Centers. The study was carried out in one year from May 2014 to April 2015. Results: 45.7% tuberculosis patients were unemployed. 35.29% of TB patients were educated up to primary 24.70% pt were illiterate. 54.11% of TB patients belong to upper lower class. 34.11% were in lower class. Among the TB patients 76.47% were smoker whereas 23.53% were non smoker. Among the TB patients 77.65% were alcoholic whereas 22.35% were non alcoholic. 83.53% TB patients had no family h/o of contact while 16.47% TB patients had Family h/o of contact. Among tuberculosis patients 77.65% were aware about the curability of tuberculosis while 22.35% were not aware about the curability of TB. 34.12% patients were aware about Modes of Transmission of Tuberculosis and 65.88% TB patients were not aware about Modes of Transmission of Tuberculosis. Conclusion: It was concluded that socioeconomic standard of tuberculosis is low and give health education to improve personal habit and stop TB Transmission. Awareness about modes of transmission of tuberculosis was low. Awareness about curability of tuberculosis and knowledge and proper treatment of pulmonary Tuberculosis is poor. Keywords: curability, DOTS Centre, mode of transmission, occupation, socioeconomic status, TB patients.

Factors Influencing Patient Adherence to Tuberculosis Treatment in Ethiopia: A Literature Review.

Background: Tuberculosis (TB) is a major global public health problem and one of the leading causes of death among infectious diseases. Although TB can be cured with first-line antibiotics treatment of 6 months regimen, non-adherence to the treatment remains the main challenge for TB prevention and control. Interventions to promote adherence need to address multiple underlying factors linked to non-adherence, which requires a synthesis of studies to understand these factors in the local context. Our review accordingly examines these factors for TB treatment in Ethiopia. Methods: Articles were searched from PubMed and ScienceDirect databases, as well as manual searches through Google and Google Scholar search engines. Both quantitative and qualitative studies that showed factors associated with or reasons for non-adherence, default or loss to follow up from TB treatment were included. A total of 276 articles were screened, and 29 articles were ultimately included in the review. Findings: The extracted factors were synthesized thematically into seven dimensions of patient-centred, social, economic, health system, therapy, lifestyle, and geographic access factors. More than 20 distinct factors were identified under these headings. Some of these factors may also apply quite widely in other settings, with greater or lesser influence, but some are particularly applicable to the Ethiopian setting. Conclusion: Helping patients to achieve full adherence to TB medication is a complex problem as it is influenced by interplay between many factors. Healthcare managers, providers, and researchers need to consider and address multiple underlying factors when designing adherence interventions. This work provides a reference set of such factors for Ethiopian interventions.

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

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.

Study of defaulters amongst pulmonary tuberculosis patients attending DOTS centre in urban area of Ghaziabad district

Objectives: to determine the default rate among above Tuberculosis patients under DOTS and to elicit reasons of treatment default in the above tuberculosis patients. Setting: The study was carried out in selected DOTS centers of district Ghaziabad. Sampling: Multistage sampling. Study period: May 2014 to April 2015.