Optimistic concurrency control relies on end-of-transaction validation rather than lock acquisition prior to data accesses. Optimistic concurrency control is popular and various systems employ it based on a conviction that it increases concurrency, performance, and scalability. In contrast, we have concluded that optimistic concurrency control permits more concurrency than pessimistic concurren...

Transactional Memory (TM) is an approach aiming to simplify concurrent programming by automating synchronization while maintaining efficiency. TM usually employs the optimistic concurrency control approach, which relies on transactions aborting and restarting if conflicts occur. However, an aborted transaction can still leave some effects in the system that cannot be cleaned up, if irrevocable ...

Message logging protocols are an integral part of a technique for implementing processes that can recover from crash failures. All message logging protocols require that, when recovery is complete, there be no orphan processes, which are surviving processes whose states are inconsistent with the recovered state of a crashed process. We give a precise speciication of the consistency property \no...

BACKGROUND Preparing for potentially threatening events in the future is essential for survival. Anticipating the future to be unpleasant is also a cognitive key feature of depression. We hypothesized that 'pessimism'-related emotion processing would characterize brain activity in major depression.MethodDuring functional magnetic resonance imaging, depressed patients and a healthy control group...

Message-logging protocols are an integral part of a popular technique for implementing processes that can recover from crash failures. All message-logging protocols require that, when recovery is complete, there be no orphan processes , which are surviving processes whose states are inconsistent with the recovered state of a crashed process. We give a precise speci cation of the consistency pro...

In nonparametric statistics an optimality criterion for estimation procedures is provided by the minimax rate of convergence. However this classical point of view is subject to controversy as it requires to look for the worst behaviour reached by an estimation procedure in a given space. The purpose of this paper is to show that this is not justified as the minimax risk often coincides with a g...

Recent developments in the theory of choice under uncertainty and risk yield a pessimistic decision theory that replaces the classical expected utility criterion with a Choquet expectation that accentuates the likelihood of the least favorable outcomes. A parallel theory has recently emerged in the literature on risk assessment. It is shown that pessimistic portfolio optimization based on the C...