Recently several authors have stressed and illustrated the importance of including a second kind of negation (explicit negation) in logic programs besides \negation as failure", and its use in deductive databases, knowledge representation, and nonmonotonic reasoning. By introducing explicit negation into logic programs contradiction may appear. In this work we present two approaches for dealing...

Equation of motion for real dust particle under the action of electromagnetic radiation is more general than equation of motion corresponding to standardly used Poynting-Robertson effect (P-R effect). As a consequence, orbital evolution of particles may significantly differ from that corresponding to the P-R effect. The paper discusses recently published (Icarus, June 2002) derivation of equati...

This paper is an attempt to attain a new and profound model of the nature’s structure using a vortex-ringfractal theory (VRFT). Scientists have been trying to explain some phenomena in Nature that have not been explained so far. The aim of this paper is the vortex-ring-fractal modeling of elements in the Mendeleev’s periodic table, which is not in contradiction to the known laws of nature. We w...

in the present era, the cultural heritage of the nations is taken into consideration, and has found great significance in several aspects. this importance has enforced the nations to enact their particular laws in cultural heritage domain; among the rest, the ownership of historic-cultural monuments. these laws lead to the restriction of private ownerships in many cases. in the first glance, it...