6,917 research outputs found
How much of commonsense and legal reasoning is formalizable? A review of conceptual obstacles
Fifty years of effort in artificial intelligence (AI) and the formalization of legal reasoning have produced both successes and failures. Considerable success in organizing and displaying evidence and its interrelationships has been accompanied by failure to achieve the original ambition of AI as applied to law: fully automated legal decision-making. The obstacles to formalizing legal reasoning have proved to be the same ones that make the formalization of commonsense reasoning so difficult, and are most evident where legal reasoning has to meld with the vast web of ordinary human knowledge of the world. Underlying many of the problems is the mismatch between the discreteness of symbol manipulation and the continuous nature of imprecise natural language, of degrees of similarity and analogy, and of probabilities
Adaptive evolution of transcription factor binding sites
The regulation of a gene depends on the binding of transcription factors to
specific sites located in the regulatory region of the gene. The generation of
these binding sites and of cooperativity between them are essential building
blocks in the evolution of complex regulatory networks. We study a theoretical
model for the sequence evolution of binding sites by point mutations. The
approach is based on biophysical models for the binding of transcription
factors to DNA. Hence we derive empirically grounded fitness landscapes, which
enter a population genetics model including mutations, genetic drift, and
selection. We show that the selection for factor binding generically leads to
specific correlations between nucleotide frequencies at different positions of
a binding site. We demonstrate the possibility of rapid adaptive evolution
generating a new binding site for a given transcription factor by point
mutations. The evolutionary time required is estimated in terms of the neutral
(background) mutation rate, the selection coefficient, and the effective
population size. The efficiency of binding site formation is seen to depend on
two joint conditions: the binding site motif must be short enough and the
promoter region must be long enough. These constraints on promoter architecture
are indeed seen in eukaryotic systems. Furthermore, we analyse the adaptive
evolution of genetic switches and of signal integration through binding
cooperativity between different sites. Experimental tests of this picture
involving the statistics of polymorphisms and phylogenies of sites are
discussed.Comment: published versio
Absorptive capacity and the growth and investment effects of regional transfers : a regression discontinuity design with heterogeneous treatment effects
Researchers often estimate average treatment effects of programs without investigating heterogeneity across units. Yet, individuals, firms, regions, or countries vary in their ability, e.g., to utilize transfers. We analyze Objective 1 Structural Funds transfers of the European Commission to regions of EU member states below a certain income level by way of a regression discontinuity
design with systematically heterogeneous treatment effects. Only about 30% and 21% of the regions - those with sufficient human capital and good-enough institutions - are able to turn transfers into faster per-capita
income growth and per-capita investment. In general, the variance of the treatment effect is much bigger than its mean
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The Rumsfeld Effect: The unknown unknown
A set of studies tested whether people can use awareness of ignorance to provide enhanced test consistency over time if they are allowed to place uncertain items into a âdonât knowâ category. For factual knowledge this did occur, but for a range of other forms of knowledge relating to conceptual knowledge and personal identity, no such effect was seen. Known unknowns would appear to be largely restricted to factual kinds of knowledge
Concepts and Their Dynamics: A Quantum-Theoretic Modeling of Human Thought
We analyze different aspects of our quantum modeling approach of human
concepts, and more specifically focus on the quantum effects of contextuality,
interference, entanglement and emergence, illustrating how each of them makes
its appearance in specific situations of the dynamics of human concepts and
their combinations. We point out the relation of our approach, which is based
on an ontology of a concept as an entity in a state changing under influence of
a context, with the main traditional concept theories, i.e. prototype theory,
exemplar theory and theory theory. We ponder about the question why quantum
theory performs so well in its modeling of human concepts, and shed light on
this question by analyzing the role of complex amplitudes, showing how they
allow to describe interference in the statistics of measurement outcomes, while
in the traditional theories statistics of outcomes originates in classical
probability weights, without the possibility of interference. The relevance of
complex numbers, the appearance of entanglement, and the role of Fock space in
explaining contextual emergence, all as unique features of the quantum
modeling, are explicitly revealed in this paper by analyzing human concepts and
their dynamics.Comment: 31 pages, 5 figure
Inconstant Planck's constant
Motivated by the Dirac idea that fundamental constant are dynamical variables
and by conjectures on quantum structure of spacetime at small distances, we
consider the possibility that Planck constant is a time depending
quantity, undergoing random gaussian fluctuations around its measured constant
mean value, with variance and a typical correlation timescale
. We consider the case of propagation of a free particle and a
one--dimensional harmonic oscillator coherent state, and show that the time
evolution in both cases is different from the standard behaviour. Finally, we
discuss how interferometric experiments or exploiting coherent electromagnetic
fields in a cavity may put effective bounds on the value of .Comment: To appear on the International Journal of Modern Physics
Typicality, graded membership, and vagueness
This paper addresses theoretical problems arising from the vagueness of language terms, and intuitions of the vagueness of the concepts to which they refer. It is argued that the central intuitions of prototype theory are sufficient to account for both typicality phenomena and psychological intuitions about degrees of membership in vaguely defined classes. The first section explains the importance of the relation between degrees of membership and typicality (or goodness of example) in conceptual categorization. The second and third section address arguments advanced by Osherson and Smith (1997), and Kamp and Partee (1995), that the two notions of degree of membership and typicality must relate to fundamentally different aspects of conceptual representations. A version of prototype theoryâthe Threshold Modelâis proposed to counter these arguments and three possible solutions to the problems of logical selfcontradiction and tautology for vague categorizations are outlined. In the final section graded membership is related to the social construction of conceptual boundaries maintained through language use
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