From electronic design problems to resolution proofs to SAT solvers, this book focuses on the satisfiabilityof theories that consist of propositional logic ...

We investigate the complexity of finding solutions to infinite recursive constraint satisfaction problems. We show that, in general, the problem of finding a solution to an infinite recursive constraint satisfaction problem is equivalent to the problem of finding an infinite path through a recursive tree. We also identify natural classes of infinite recursive constraint satisfaction problems where the problem of finding a solution to the infinite recursive constraint satisfaction problem is equivalent to the problem of finding an infinite path through (...) finitely branching recursive trees or recursive binary trees. There are a large number of results in the literature on the complexity of the problem of finding an infinite path through a recursive tree. Our main result allows us to automatically transfer such results to give equivalent results about the complexity of the problem of finding a solution to a recursive constraint satisfaction problem. (shrink)

Kill one person, and it is considered murder.Kill ten thousand person, and it is considered foreign policy.-Anonymous.

Kill one person, and it is considered murder.Kill ten thousand person, and it is considered foreign policy.-Anonymous.

Planning of effective responses to the recent resurgence of tuberculosis in the United States, and particularly in New York City, requires review of our knowledge of the factors that led to the decline of tuberculosis in the U.S. and other countries during the nineteenth and the first three-quarters of the twentieth century, and the recent changes in these same factors and the rise of new factors that have contributed to its resurgence. Because the analysis of the impact of all of (...) these factors in both the remote and the recent past is controversial, it is important to use a well-defined framework to organize the analysis. The framework we will use is shown in Table 1. To the classic epidemiologic triad of Agent, Host and Environment it adds the category of Health Services. In this paper we redefine both the classic and new categories using current disciplines and concepts applicable to tuberculosis. (shrink)

Planning of effective responses to the recent resurgence of tuberculosis in the United States, and particularly in New York City, requires review of our knowledge of the factors that led to the decline of tuberculosis in the U.S. and other countries during the nineteenth and the first three-quarters of the twentieth century, and the recent changes in these same factors and the rise of new factors that have contributed to its resurgence. Because the analysis of the impact of all of (...) these factors in both the remote and the recent past is controversial, it is important to use a well-defined framework to organize the analysis. The framework we will use is shown in Table 1. To the classic epidemiologic triad of Agent, Host and Environment it adds the category of Health Services. In this paper we redefine both the classic and new categories using current disciplines and concepts applicable to tuberculosis. (shrink)

Using the Makkai's duality for first-order logic, we characterise effective descent morphisms in 2-categories of pretoposes and Barr-exact categories. In both cases they coincide with conservative morphisms. We show that in those 2-categories the 2-coregular factorisations are exactly quotient-conservative factorisations. We also prove a generalisation of the Makkai duality for pseudoelementary categories.

In my paper I review the main strategies adopted by two leading schools in cognitive science, symbolic artificial intelligence (AI) and connectionism, in modeling time-dependent phenomena such as learning. In particular, I briefly mention shortcomings of non-monotonic logic approach that dominates symbolic AI. I also discuss the problems that beset the recurrent networks approach advocated by connectionists (e.g., S. Grossberg) and philosophers (e.g., P. Churchland), who focus their attention on oscillatory behavior of such networks. I point out that neither approach (...) adequately captures essential features of the dynamics of human temporal awareness. Finally, I develop certain ideas borrowed from neurophysiologists (e.g., W. Freeman) and system theorists and describe the brain-mind, the entity that is capable of producing temporal awareness, as a self-organizing system that exhibits chaotic dynamics and generates a dynamic structure that resembles the chaotic hierarchy o Rossler. (shrink)

In this paper, we argue that several recent ‘wide’ perspectives on cognition (embodied, embedded, extended, enactive, and distributed) are only partially relevant to the study of cognition. While these wide accounts override traditional methodological individualism, the study of cognition has already progressed beyond these proposed perspectives towards building integrated explanations of the mechanisms involved, including not only internal submechanisms but also interactions with others, groups, cognitive artifacts, and their environment. The claim is substantiated with reference to recent developments in the (...) study of “mindreading” and debates on emotions. We claim that the current practice in cognitive (neuro)science has undergone, in effect, a silent mechanistic revolution, and has turned from initial binary oppositions and abstract proposals towards the integration of wide perspectives with the rest of the cognitive (neuro)sciences. (shrink)

In the paper [8], the first author developped a topos- theoretic approach to reference and modality. (See also [5]). This approach leads naturally to modal operators on locales (or spaces without points). The aim of this paper is to develop the theory of such modal operators in the context of the theory of locales, to axiomatize the propositional modal logics arising in this context and to study completeness and decidability of the resulting systems.

A number of nonmonotonic reasoning formalisms have been introduced to model the set of beliefs of an agent. These include the extensions of a default logic, the stable models of a general logic program, and the extensions of a truth maintenance system among others. In [13] and [16], the authors introduced nonmonotomic rule systems as a nonlogical generalization of all essential features of such formulisms so that theorems applying to all could be proven once and for all. In this paper, (...) we extend Rieter's normal default theories, which have a number of the nice properties which make them a desirable context for belief revision, to the setting of nonmonotonic rule systems. Reiter defined a default theory to be normal if all the rules of the default theory satisfied a simple syntatic condition. However, this simple syntatic condition has no obvious analogue in the setting of nonmonotonic rule systems. Nevertheless, an analysis of the proofs of the main results on normal default theories reveals that the proofs do not rely on the particular syntactic form of the rules but rather on the fact that all rules have a certain consistency property. This led us to extend the notion of normal default theories with respect to a general consistency property. This extended notion of normal default theories, which we call Forward Chaining normal , is easily lifted to nonmonotomic rule systems and hence applies to general logic programs and truth maintenance. (shrink)

Gelfond and Lifschitz proposed the notion of a stable model of a logic program. We establish that the set of all stable models in a Herbrand universe of a recursive logic program is, up to recursive renaming, the set of all infinite paths of a recursive, countably branching tree, and conversely. As a consequence, the problem, given a recursive logic program, of determining whether it has at least one stable model, is Σ11-complete. Due to the equivalences established in the authors' (...) previous nonmonotone rule systems papers ), this applies equally to truth maintenance systems and default logics. (shrink)

This breakthrough volume integrates European, British, and American scholarship in advanced areas of philosophy and decision theory. Contributions cover a broad area of economics--from criticism of institutional economics to examination of the role of induction in economic forecasting.

ObjectiveTo prospectively study the cingulate cortex for the localization and role of the grasping action in humans during electrical stimulation of depth electrodes.MethodsAll the patients with intractable focal epilepsy and a depth electrode stereotactically placed in the cingulate cortex, as part of their pre-surgical epilepsy evaluation from 2015 to 2017, were included. Cortical stimulation was performed and examined for grasping actions. Post-implantation volumetric T1 MRIs were co-registered to determine the exact electrode position.ResultsFive patients exhibited contralateral grasping actions during electrical stimulation. (...) All patients had electrodes implanted in the ventral bank of the right cingulate sulcus adjacent to the vertical anterior commissure line. Stimulation of other electrodes in adjacent regions did not elicit grasping.ConclusionGrasping action elicited from a localized region in the mid-cingulate cortex directly supports the concept of the cingulate cortex being crucially involved in the grasping network. This opens an opportunity to explore this region with deep brain stimulation as a motor neuromodulation target for treatment in specific movement disorders or neurorehabilitation. (shrink)

For a complete Heyting lattice , we define a category Etale (). We show that the category Etale () is equivalent to the category of the sheaves over , Sh(), hence also with -valued sets, see [2], [1]. The category Etale() is a generalization of the category Etale (X), see [1], where X is a topological space.