Decision making under uncertainty is usually based on the comparative evaluation of different alternatives by means of a decision criterion. In a qualitative setting, pessimistic and optimistic criteria have been proposed. In that setting, the whole decision process is compacted into a criterion formula on the basis of which alternatives are compared. It is thus impossible for an end user to un...

A real-time database system differs from a conventional database system because in addition to the consistency constraints of the database, timing constraints of individual transaction need to be satisfied. Various real-time transaction scheduling algorithms have been proposed which employ either a pessimistic or an optimistic approach to concurrency control. In this paper, we present new real-...

In Possibilistic Decision Theory (PDT), decisions are ranked by a pessimistic and an optimistic qualitative criteria. The preference relations induced by these criteria have been axiomatized by corresponding sets of rationality postulates, both à la Neumann-Morgenstern and à la Savage. In this paper we first address a particular issue regarding the axiomatic systems of PDT à la von Neumann and ...

Software has a far ranging nature and sometimes it is difficult to predict the cost. So, it was demanded to develop some useful models that predict the accurate cost, schedule and quality of a software product. There is a great need to accurately predict the cost by selecting the appropriate estimation method. Expert Based Judgment is quite successful. Wideband Delphi estimation comes under thi...

In this paper, we present a new approach to synchronization in real-time systems. Existing methods for synchronization in real-time systems are pessimistic, and use blocking to enforce concurrency control. Protocols such as the priority ceiling protocol have been proposed to reduce the priority inversion that occurs when low priority tasks block high priority tasks. However, the priority ceilin...

The combination of classifiers has been proposed as a method to improve the accuracy achieved by a single classifier. In this study, the performances of optimistic and pessimistic ordered weighted averaging operators for protein secondary structure classifiers fusion have been investigated. Each secondary structure classifier outputs a unique structure for each input residue. We used confusion ...

We study the problem of computing an equilibrium in leader-follower games with a single leader and multiple followers where, after the leader’s commitment to a mixed strategy, the followers play simultaneously in a noncooperative way, reaching a Nash equilibrium. We tackle the problem from a bilevel programming perspective. Since, given the leader’s strategy, the followers’ subgame may admit mu...

Modern concurrent programming benefits from a large variety of synchronization techniques. These include conventional pessimistic locking, as well as optimistic techniques based on conditional synchronization primitives or transactional memory. Yet, it is unclear which of these approaches better leverage the concurrency inherent to multi-cores. In this paper, we compare the level of concurrency...

In distributed systems, the communication among group members often needs ordered messages to guarantee that every member receives the messages in the same order. Oftentimes, changes in distributed computing environment occur and this undermines the assumption of any ordering algorithm. Therefore, it is difficult to presume a suitable ordering algorithm and apply a single algorithm throughout t...