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...

We address the issue of deriving a semantically equivalent optimistic computation from a pessimistic computation by application-independent transformations. Computations are modeled by program dependence graphs (pdgs). The semantics of a computation is de-ned by a mapping from an initial state to a nal state, and is realized by a graph rewriting system. Semantics-preserving transformations are ...

An important cytokine role in dengue fever pathogenesis has been described. These molecules can be associated with haemorrhagic manifestations, coagulation disorders, hypotension and shock, all symptoms implicated in vascular permeability and disease worsening conditions. Several immunological diseases have been treated by cytokine modulation and dexamethasone is utilized clinically to treat pa...

In this paper, we propose to combine the advantages of semantic wikis and P2P wikis in order to design a peer-to-peer semantic wiki. The main challenge is how to merge wiki pages that embed semantic annotations. Merging algorithms used in P2P wiki systems have been designed for linear text and not for semantic data. In this paper, we evaluate two optimistic replication algorithms to build a P2P...

Overview • The Object Space Approach: object-oriented essentials and decoupled communication. • Example: a distributed time service. • A distributed protoypical implementation of Object Space. • Employing replication and optimistic asynchrony: a more efficient implementation.

Optimism is a powerful technique for increasing concurrency. A program can gain concurrency by making an optimistic assumption about its future state, and verifying the assumption in parallel with computations based on the optimistic assumption. To date, use of optimism has been restricted to specialized systems due to the diiculty of writing optimistic programs. In this paper, we deene and jus...

We design cryptographic protocols that recognize best case (optimistic) situations and exploit them. As a case study, we present a new concurrent zeroknowledge protocol that is expected to require only a small constant number of rounds in practice. To prove that our protocol is secure, we identify a weak property of concurrent schedules—called footer-freeness—that suffices for efficient simulat...