Abstract
The detection of anomalies in computer environments, like network intrusion detection, computer virus or spam classification, is usually based on some form of pattern search on a database of "signatures " for known anomalies. Although very successful and widely deployed, these approaches are only able to cope with anomalous events that have already been seen. To cope with these weaknesses, the "behaviour" based systems has been deployed. Although conceptually more appealing, they have still an impractical high rate of false alarms. The vertebrate Immune System is an emergent and appealing metaphor for new ideas on anomaly detection, being already adopted some algorithms and theoretical theories in particular fields, such as network intrusion detection. In this paper we present a temporal anomaly detection architecture based on the Grossman's Tunable Activation Threshold (TAT) hypothesis. The basic idea is that the repertoire of immune cells is constantly tuned according to the cells temporal interactions with the environment and yet retains responsiveness to an open-ended set of abnormal events. We describe some preliminary work on the development of an anomaly detection algorithm derived from TAT and present the results obtained thus far using some synthetic data-sets.

Abstract
One of the advantages of logic programming is the fact that it offers several sources of implicit parallelism. One particularly interesting form of And-Parallelism is Independent And-Parallelism (IAP). Most work on the implementation of IAP is based on Hermenegildo's RAP-WAM. Unfortunately there are some drawbacks associated with the classical approaches based on the use of parcalls and markers. One first observation is that the introduction of parcall frames significantly slows down sequential execution. Moreover, it may result in fine-grained parallel work. We found these problems to be particularly significant in the context of the implementation of combined AND/OR systems. In this paper we take a fresh look at this issue. Our goal is to start from a standard sequential Prolog implementation and try to discover the minimal number of changes that would be required for an efficient implementation of IAP. The key ideas in our design are to (i) to always take advantage of analogy between or-parallelism and IAP; (ii) to avoid creating new structures by adapting preexistingx WAM data-structures wherever possible; and (iii) to avoid major changes to the compiler. The authors would like to acknowledge and thank the contribution and support from Fernando Silva. The work has also benefitted from discussions with Luis Fernando Castro, Ines de Castro Dutra, Kish Shen, Gopal Gupta, and Enrico Pontelli. Our work has been partly supported by Fundaçã da Ciencia e Tecnologia and JNICT under the projects Melodia (JNICT/PBIC/C/TIT/2495/95) and Dolphin (PRAXIS/2/2.l/TIT/1577/95). © 2000 Published by Elsevier B.V.

Abstract
One important problem in the design of novel logic programming systems is the support of several forms of implicit parallelism. A new binding model, the Sparse Binding Array (SBA), has been proposed for the efficient and simplified integration of Independent-And, Determinate-And and Or-parallelism. In this paper we report on the use of this model for pure Or-parallelism. The work discusses the major implementation issues in supporting this binding model for pure Or-parallelism. We show that an implementation based on this Binding model is more efficient then the original Aurora using tbe traditional Binding Array model [16]. Moreover, we explain how the notion of a variable level can be used to reduce overheads of the Orparallel system. Our results in supporting pure or-parallelism show that the approach is very promissing for combined paralell systems.

Abstract
Prolog programs have explicit parallelism, that is, parallelism which can be exploited by a machine with minimal user effort. Or-parallelism is one such form of parallelism, and is particularly useful in that it is present in the many Prolog applications where several alternatives need to be considered. Or-parallelism has been exploited successfully in several systems, and especially in the Aurora and Muse systems. In this paper we analyze the portability of these two parallel systems onto a commercial shared memory parallel computer, a Sun SPARCcenter 2000 with 8 processors, running the Solaris 2.2 Operating System. We also analyze both systems' performance for classical benchmark programs and for two large Prolog applications.

Abstract
This paper presents DAOS, a model for exploitation of Andand Or-parallelism in logic programs. DAOS assumes a physically distributed memory environment and a logically shared address space. Exploiting both major forms of implicit parallelism should serve a broadest range of applications. Besides, a model that uses a distributed memory environment provides scalability and can be implemented over a computer network. However, distributed implementations of logic programs have to deal with communication overhead and inherent complexity of distributed memory managent. DAOS overcomes those problems through the use of a distributed shared memory layer to provide single-writer, multiple-readers sharing for the main execution stacks combined with explicit message passing for work distribution and management.

Abstract