712 research outputs found
Typed feature structures, definite equivalences, greatest model semantics, and nonmonotonicity
Typed feature logics have been employed as description languages in modern type-oriented grammar theories like HPSG and have laid the theoretical foundations for many implemented systems. However, recursivity pose severe problems and have been addressed through specialized powerdomain constructions which depend on the particular view of the logician. In this paper, we argue that definite equivalences introduced by Smolka can serve as the formal basis for arbitrarily formalized typed feature structures and typed feature-based grammars/lexicons, as employed in, e.g., TFS or TDL. The idea here is that type definitions in such systems can be transformed into an equivalent definite program, whereas the meaning of the definite program then is identified with the denotation of the type system. Now, models of a definite program P can be characterized by the set of ground atoms which are logical consequences of the definite program. These models are ordered by subset inclusion and, for reasons that will become clear, we propose the greatest model as the intended interpretation of P, or equivalent, as the denotation of the associated type system. Our transformational approach has also a great impact on nonmonotonically defined types, since under this interpretation, we can view the type hierarchy as a pure transport medium, allowing us to get rid of the transitivity of type information (inheritance), and yielding a perfectly monotonic definite program
Anomalous near-field heat transfer between a cylinder and a perforated surface
We predict that the radiative heat-transfer rate between a cylinder and a
perforated surface depends non-monotonically on their separation. This
anomalous behavior, which arises due to near-field effects, is explained using
a heuristic model based on the interaction of a dipole with a plate. We show
that nonmonotonicity depends not only on geometry and temperature but also on
material dispersion - for micron and submicron objects, nonmonotonicity is
present in polar dielectrics but absent in metals with small skin depths
A Nonmonotonic Sequent Calculus for Inferentialist Expressivists
I am presenting a sequent calculus that extends a nonmonotonic consequence relation over an atomic language to a logically complex language. The system is in line with two guiding philosophical ideas: (i) logical inferentialism and (ii) logical expressivism. The extension defined by the sequent rules is conservative. The conditional tracks the consequence relation and negation tracks incoherence. Besides the ordinary propositional connectives, the sequent calculus introduces a new kind of modal operator that marks implications that hold monotonically. Transitivity fails, but for good reasons. Intuitionism and classical logic can easily be recovered from the system
Typed feature structures, definite equivalences, greatest model semantics, and nonmonotonicity
Typed feature logics have been employed as description languages in modern type-oriented grammar theories like HPSG and have laid the theoretical foundations for many implemented systems. However, recursivity pose severe problems and have been addressed through specialized powerdomain constructions which depend on the particular view of the logician. In this paper, we argue that definite equivalences introduced by Smolka can serve as the formal basis for arbitrarily formalized typed feature structures and typed feature-based grammars/lexicons, as employed in, e.g., TFS or TDL. The idea here is that type definitions in such systems can be transformed into an equivalent definite program, whereas the meaning of the definite program then is identified with the denotation of the type system. Now, models of a definite program P can be characterized by the set of ground atoms which are logical consequences of the definite program. These models are ordered by subset inclusion and, for reasons that will become clear, we propose the greatest model as the intended interpretation of P, or equivalent, as the denotation of the associated type system. Our transformational approach has also a great impact on nonmonotonically defined types, since under this interpretation, we can view the type hierarchy as a pure transport medium, allowing us to get rid of the transitivity of type information (inheritance), and yielding a perfectly monotonic definite program
Size dependence of second-order hyperpolarizability of finite periodic chain under Su-Schrieffer-Heeger model
The second hyperpolarizability of
double-bond finite chain of trans-polyactylene is analyzed using the
Su-Schrieffer-Heeger model to explain qualitative features of the
size-dependence behavior of . Our study shows that is
{\it nonmonotonic} with and that the nonmonotonicity is caused by the
dominant contribution of the intraband transition to in polyenes.
Several important physical effects are discussed to reduce quantitative
discrepancies between experimental and our resultsComment: 3 figures, 1 tabl
Housing prices and multiple employment nodes: is the relationship nonmonotonic?
Standard urban economic theory predicts that house prices will decline with distance from the central business district. Empirical results have been equivocal, however. Disjoints between theory and empirics may be due to a nonmonotonic relationship between house prices and access to employment arising from the negative externalities associated with proximity to multiple centres of employment. Based on data from Glasgow (Scotland), we use gravity-based measures of accessibility estimated using a flexible functional form that allows for nonmonotonicity. The results are thoroughly tested using recent advances in spatial econometrics. We find compelling evidence of a nonmonotonic effect in the accessibility measure and discuss the implications for planning and housing policy
Metallic behavior in Si/SiGe 2D electron systems
We calculate the temperature, density, and parallel magnetic field dependence
of low temperature electronic resistivity in 2D high-mobility Si/SiGe quantum
structures, assuming the conductivity limiting mechanism to be carrier
scattering by screened random charged Coulombic impurity centers. We obtain
comprehensive agreement with existing experimental transport data, compellingly
establishing that the observed 2D metallic behavior in low-density Si/SiGe
systems arises from the peculiar nature of 2D screening of long-range impurity
disorder. In particular, our theory correctly predicts the experimentally
observed metallic temperature dependence of 2D resistivity in the fully
spin-polarized system
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