1.

Terminal Area Simulation System User's Guide - Version 10.0
- Switzer, George F.; Proctor, Fred H.
The Terminal Area Simulation System (TASS) is a three-dimensional, time-dependent, large eddy simulation model that has been developed for studies of wake vortex and weather hazards to aviation, along with other atmospheric turbulence, and cloud-scale weather phenomenology. This document describes the source code for TASS version 10.0 and provides users with needed documentation to run the model. The source code is programed in Fortran language and is formulated to take advantage of vector and efficient multi-processor scaling for execution on massively-parallel supercomputer clusters. The code contains different initialization modules allowing the study of aircraft wake vortex interaction with the atmosphere...

2.

A Proof Theory for Constructive Default Logic
- Yao-hua Tan
. We present what we call Constructive Default Logic (CDL) - a default logic in which the fixedpoint definition of extensions is replaced by a constructive definition which yield so-called constructive extensions. Selection functions are used to represent explicitly the control of the reasoning process in this default logic. It is well-known that Reiter's original default logic lacks, in general, a default proof theory. We will show that CDL does have a default proof theory, and we will also show that this is related to the fact that CDL has the existence property for constructive extensions and that it also...

3.

Using First-Order Probability Logic for the Construction of Bayesian Networks
- Fahiem Bacchus
We present a mechanism for constructing graphical models, specifically Bayesian networks, from a knowledge base of general probabilistic information. The unique feature of our approach is that it uses a powerful first-order probabilistic logic for expressing the general knowledge base. This logic allows for the representation of a wide range of logical and probabilistic information. The model construction procedure we propose uses notions from direct inference to identify pieces of local statistical information from the knowledge base that are most appropriate to the particular event we want to reason about. These pieces are composed to generate a joint probability distribution...

4.

Structural Operational Semantics for AKL
- Seif Haridi; Sverker Janson; Catuscia Palamidessi
The Andorra Kernel Language (AKL) is a concurrent constraint programming language. It can be seen as a general combination of logic programming languages such as Prolog, GHC, and Parlog, the first of which provides don't know nondeterminism, and the last two of which are concurrent logic programming languages. The constraint system is an independent parameter of the language description. In this paper, we revisit the description of Janson and Haridi [10], adding the formal machinery which is necessary in order to completely formalize the control of the computation model. To this we add a formal description of the transformational semantics...

5.

Ports for Objects in Concurrent Logic Programs
- Sverker Janson; Johan Montelius; Seif Haridi
We introduce ports, an alternative to streams, as communication support for object-oriented programming in concurrent constraint logic programming languages. From a pragmatic point of view ports provide efficient many-toone communication, object identity, means for garbage collection of objects, and opportunities for optimised compilation techniques for concurrent objects. From a semantic point of view, ports preserve the monotonicity of the constraint store which is a crucial property of all concurrent constraint languages. We also show that the Exclusive-read, Exclusive-write PRAM model of parallel computation can be realised quite faithfully using ports in terms of space and time complexity, thus allowing arbitrary...

6.

Encoding Dependent Types in an Intuitionistic Logic
- Amy Felty
Various languages have been proposed as specification languages for representing a wide variety of logics. The development of typed -calculi has been one approach toward this goal. The logical framework (LF), a -calculus with dependent types is one example of such a language. A small subset of intuitionistic logic with quantification over the simply typed -calculus has also been proposed as a framework for specifying general logics. The logic of hereditary Harrop formulas with quantification at all non-predicate types, denoted here as hh ! , is such a meta-logic. In this paper, we show how to translate specifications in LF...

7.

Programming Paradigms of the Andorra Kernel Language
- Sverker Janson; Seif Haridi
The Andorra Kernel Language (AKL) is introduced. It is shown how AKL provides the programming paradigms of both Prolog and GHC. This is the original goal of the design. However, it has also been possible to provide capabilities beyond that of Prolog and GHC. There are means to structure search, more powerful than plain backtracking. It is possible to encapsulate search in concurrent reactive processes. It is also possible to write a multi-way merger with constant delay. In these respects AKL is quite original. Although AKL is an instance of our previously introduced Kernel Andorra Prolog framework, this exposition contains...

8.

Why Machines Cannot be Conscious
- Subhash C. Kak
Mental processes are abstracted from a subset of the physical universe; these, in turn, lead to the world of ideas. Although these ideas include quantum logic, no credible way has yet been found that constructs machines which use superimposed possibilities in the style of quantum logic, more general in computing power to machines based on classical logic. Machine theories are based exclusively on classical logic and socalled "quantum computers" are equivalent, computationally, to classical computers. A machine cannot be conscious because it can only respond according to a pre-determined program. Viewed as a machine, there is no explanation for the...

9.

Retractions in Comparing Prolog Semantics
- De Bruin Faculty; A. De Bruin; Y
We present an operational model O and a continuation based denotational model D for a uniform variant of Prolog, including the cut operator. The two semantical definitions make use of higher order transformations F and Y, respectively. We prove O and D equivalent in a novel way by comparing yet another pair of higher order transformations F and Y , that yield F and Y, respectively, by application of a suitable abstraction operator. Section 1 Introduction In [BV] we presented both an operational and a denotational continuation based semantics for the core of Prolog, and we proved these two semantics...

10.

Proving Compiler Correctness with Evolving Algebra Specifications
- Bernhard Beckert; Reiner Hähnle
Introduction The purpose of this note is to define a framework for proving compiler correctness with evolving algebra (EA) specifications [2]. Although our specific domain is the verification of a Prolog-toWAM compiler [1, 3], we think that our considerations are fairly general and they should be useful in other areas as well. The starting point for us was the observation that the notions of correctness and completeness as used in [1] become quite counterintuitive when seen from the point of view of compiler construction. First we will define our general view of the semantics of a programming language, of how...

11.

Overview of F-logic from Database Transformation Perspective
- György Kovács; Patrick Van Bommel
This paper is the result of a preparatory work for our approach to the transformation of conceptual data models into object-oriented database systems. In our approach this transformation is captured within the framework of a two level architecture. Conceptual models are first mapped to intermediate specifications, which are then transformed to database schemas in a given object-oriented target database environment (e.g. SQL3, ODMG). To express intermediate representations of conceptual models we use F-logic, a logic-based abstract specification language for object-oriented systems. The goal of this paper is giving a summary of F-logic in general, and from the perspective of the...

12.

Knowledge Modeling and Reusability in E x Claim
- Liviu Badea
This paper presents E x Claim, a hybrid language for knowledge representation and reasoning. Originally developed as an operationalization language for the KADS knowledge based systems (KBS) development methodology, E x Claim has a meta-level architecture: it structures the knowledge on three levels, namely the domain, inference and task level. An extension of a description logic is used for implementing the domain level. The inference and task levels are general logic programs integrated with the domain level by means of upward and downward reection rules which describe the automatic domain operations performed whenever arguments of inferences or tasks are accessed....

13.

An Overview of Computer Viruses in a Research Environment
- Matt Bishop
The threat of attack by computer viruses is in reality a very small part of a much more general threat, specifically attacks aimed at subverting computer security. This paper examines computer viruses as malicious logic in a research and development environment, relates them to various models of security and integrity, and examines current research techniques aimed at controlling the threats viruses in particular, and malicious logic in general, pose to computer systems. Finally, a brief examination of the vulnerabilities of research and development systems that malicious logic and computer viruses may exploit is undertaken. 1. Introduction A computer virus is...

14.

Enhancing Fixed Point Logic With Cardinality Quantifiers
- Lauri Hella; Henrik Imhof
Let Q IFP be any quantifier such that FO(Q IFP ), first order logic enhanced with Q IFP and its vectorizations, equals inductive fixed point logic, IFP in expressive power. It is known that for certain quantifiers Q, the equivalence FO(Q IFP ) j IFP is no longer true if Q is added on both sides [12, 13]. Rather, we have FO(Q IFP ; Q) ! IFP(Q) in such cases. We extend these results to a great variety of quantifiers, namely all unbounded simple cardinality quantifiers. Our argument also applies to partial fixed point logic, PFP . In order to...

15.

Non-monotonic Extensions of Logic Programming: Theory, Implementation and Applications
- Jürgen Dix; Luís Moniz Pereira; Postconference Workshop W; Teodor Przymusinski
) Alexander Bochman e-mail: bochman@bimacs.cs.biu.ac.il Abstract. We suggest a general logical formalism for Logic Programming (called a biconsequence relation) based on a four-valued inference. We show that it forms a proper setting for representing logic programs of a most general kind and for describing logics and semantics that characterize their behavior. In this way we also extend the connection between Logic and Logic Programming beyond positive programs. A uniform representation of various semantics for logic programs is presented. The main conclusion from this representation is that the distinction between these semantics can be largely attributed to the difference in their...

16.

The Fundamental Role of Entailment in Knowledge Representation and Reasoning
- Jingde Cheng
The hot controversy about the role of logic in AI has been repeated so far and probably will continue on as usual. An important fact is that the "logic" as the center of the controversy is classical mathematical logic and/or its various extensions, though there are some "more logical" logic systems. Until recently, what is debated by the researchers working on the fundamentals of AI is, among other things, what role the classical mathematical logic and/or its various extensions plays in knowledge representation and reasoning. As a result, most work on the fundamentals of AI are directly or indirectly based...

17.

Language Independence and Language Tolerance in Logic Programs
- Norman McCain; Hudson Turner
The consequences of a logic program depend in general upon both the rules of the program and its language. However the consequences of some programs are independent of the choice of language, while others depend on the language of the program in only a restricted way. In this paper, we define notions of language independence and language tolerance corresponding to these two cases. Furthermore, we show that there are syntactically-defined classes of programs that are language independent and language tolerant. A primary application of these results is to guarantee that for some programs it is permissible to ignore the fact...

18.

A Monotonicity Theorem for Extended Logic Programs
- Hudson Turner
Because general and extended logic programs behave nonmonotonically, it is in general difficult to predict how even minor changes to such programs will affect their meanings. This paper shows that for a restricted class of extended logic programs --- those with signings --- it is possible to state a fairly general theorem comparing the entailments of programs. To this end, we generalize (to the class of extended logic programs) the definition of a signing, first formulated by Kunen for general programs, and establish a theorem characterizing a restricted monotonicity property for signed extended programs. The theorem is formulated in terms...

19.

Constraint Handling Rules: Applications and Extensions
- Slim Abdennadher
this paper we present a finite domain solver written in CHR, which performs hard and soft constraint propagation. Hard constraints are conditions that must be satisfied, soft constraints, however, may be violated, but should be satisfied as much as possible. The solver is powerful enough to serve as the core of a university timetabling system. Then we show that a small and simple extension to CHR makes it a general-purpose constraint logic programming language. The extended language, called "CHR

20.

Symbol Parameter Conditions Min Typ Max Unit
- N-channel Trenchmos Logic Level Fet; General Description
Logic level N-channel enhancement mode Field-Effect Transistor (FET) in a plastic package using TrenchMOS technology. This product has been designed and qualified to the appropriate AEC standard for use in automotive critical applications. 1.2 Features and benefits � AEC Q101 compliant � Low conduction losses due to low on-state resistance � Suitable for logic level gate drive sources � Suitable for thermally demanding environments due to 175 °C rating 1.3 Applications � 12 V loads � Automotive and general purpose power switching � Motors, lamps and solenoids 1.4 Quick reference data