We consider the problem of deciding whether a given directed graph can be vertex partitioned into two acyclic subgraphs. Applications of this problem include testing rationality of collective consumption behavior, a subject in micro-economics. We prove that the problem is NP-complete even for oriented graphs and argue that the existence of a constant-factor approximation algorithm is unlikely f...

Immune systems face a daunting control challenge. On the one hand, they need to minimize damage from pathogens, without wasting energy and resources, but on the other must avoid initiating or perpetuating autoimmune responses. Finally, because pathogens interfere with immune function, immune systems must be robust against sabotage. We describe here how these challenges are met by two immune sys...

Several approaches generalizing association rules to fuzzy association rules have been proposed so far. While the formal specification of fuzzy associations is more or less straightforward, the evaluation of such rules by means of appropriate quality measures assumes an understanding of the semantic meaning of a fuzzy rule. In this respect, most existing proposals can be considered ad-hoc to so...

Evaluating a trainee's performance on a simulated procedure involves determining whether a specified objective was met while avoiding certain "injurious" actions that damage vulnerable structures. However, it is also important to teach the stylistic behaviors that minimize overall risk to the patient, even though these criteria may be more difficult to explicitly specify and detect. In this pap...

abstract personal knowledge management has been developed in various fields such as knowledge management, personal information management, communication psychology and philosophy of science, management, communications, and so a lot of research to a few experimental or approved about (pkm) is a research that the original data is just a few pages. so research in this area seems to be very focused...

Fig. 1. Progress of rendering virtual views of di€icult scenes containing foliage, wide baseline occlusions and reflections. View ray and texture mapping ray visibility is modelled soly according to a distribution of depth probabilities retained from the reconstruction stage. This results in so edges, so occlusion removal, partial uncertainty of depth in textureless areas, and so transition...

background: one of the problems at the present age is anxiety, feelings of hopelessness and nihilism among humans that would cause many problems in life so that stress has called new civilization diseases. this issue would be doubled importance of addressing to this subject and find a way for the treatment and prevention of mental health risk. methods: this study was conducted with library meth...

various factors are engaged in broadening the culture and structures related to individualism, humanism and egoism which have provided humans with a uniform lifestyle leaving the religious in confrontation with their environs. in order to get out of this situation, the principles of a religious life must be read out and structured as ignoring any principle may have considerable qualitative and ...