This paper is an enquiry into the logical, metaphysical, and physical possibility of time travel understood in the sense of the existence of closed worldlines that can be traced out by physical objects. We argue that none of the purported paradoxes rule out time travel either on grounds of logic or metaphysics. More relevantly, modern spacetime theories such as general relativity seem to permit...

Ecem Yıldız a, Yeliz Ekinci b a Institute of Graduate Studies in Science and Engineering, Istanbul Bilgi University, Istanbul, Turkey b Department of Industrial Engineering, Istanbul Bilgi University, Istanbul, Turkey Abstract: This study solves the facility location problem of an IT service company whose main problem is to arrive at the customer’s site in the shortest time when support is ne...

Graph theory has numerous application to problems in systems analysis, operations research, economics, and transportation. However, in many cases, some aspects of a graph-theoretic problem may be uncertain. For example, the vehicle travel time or vehicle capacity on a road network may not be known exactly. In such cases, it is natural to deal with the uncertainty using the methods of fuzzy sets...

Geographical Information Systems (GIS) and Image Processing Systems are usually based on classical logic and set theory. This fact pass in case of some GIS elements because of presence of many uncertainties in the nature. Hence, these GIS elements can not be based on classical model at all time. Constantly growing demands on utilization of GISs require extension of area of their usage in the wa...