Declarative programs with implicit implication

In the presence of taxonomic information, there often exists implicit implication among atoms in an interpretation domain. A general framework is proposed for the discussion of an appropriate semantics for declarative programs with respect to such implicit implication. It is first assumed that the implicit implication can be predetermined and represented by a preorder on the interpretation domain. Under the consequent constraint that every interpretation must conform to the implicit implication, an appropriate model-theoretic semantics as well as its corresponding fixpoint semantics for declarative programs is described. Based on Kostler et al.'s (1993) foundation of fixpoint with subsumption, it is shown that, it the implicit-implication relation is, in addition, assumed to be a partial order, then the meaning of a program can be determined more efficiently by application of an immediate-consequence operator which involves only reduced representations, basically consisting only of their maximal elements, of subsets of the interpretation domain     

Theory and experiment of a two-dimensional cone concentrator for sunlight

A two-dimensional cone concentrator for sunlight was theoretically and experimentally studied. The calculation revealed the maximum number of reflections that sunlight could make before exiting the cone. A higher number of reflections caused the sunlight to bounce backward to the entrance of the cone. The characteristics and geometric parameters of the cone were assessed. As the cone angle increased from 45° to 90°, the calculated concentration ratio, taking the reflection coefficient into account, increased nonlinearly from one to infinity, while the height of the cone also increased from zero to infinity. The experimental concentration ratio was found to be less than the theoretical one in all cases.     

Defeasible Inheritance Through Specialization

Typed substitution provides a means of capturing inheritance in logic deduction systems. However, in the presence of method overriding and multiple inheritance, inheritance is known to be nonmonotonic, and the semantics of programs becomes a problematic issue. This article attempts to provide a general framework, based on Dung's argumentation theoretic framework, for developing a natural semantics for programs with dynamic nonmonotonic inheritance. The relationship between the presented semantics and perfect‐model (with overriding) semantics, proposed by Dobbie and Topor (1995), is investigated. It is shown that for inheritance‐stratified programs, the two semantics coincide. However, the proposed semantics also provides correct skeptical meanings for the programs that are not inheritance‐stratified.