FRIL: A Support Logic Programming System

FRIL: A Support Logic Programming System is principally an extension of Prolog designed to facilitate the modelling of uncertainty in applications which are suitable for Prolog and need to allow for probabilistic, evidential or vague reasoning. This review was carried out on an Amstrad 1640HD. The product runs on IBM PC, XT, AT and PS/2 computers and compatibles running MS-DOS 3.0 or higher, with 640 Kb RAM. It also runs on a variety of workstations and minicomputers such as the Sun and VAX range. Prices of currently available versions are as follows:

• PC single user: £495

• PC single user with expanded memory (2 Mb): £995

• PC networks (up to ten PCs): £1495

• SUN, Apollo HP300 workstations: £2500

• MicroVax and VAX workstations (UNIX or VMS): £5000

• VAX 11/730, 11/750, 11/780 (UNIX or VMS): £6000.

The product is available from FRIL Systems Ltd, Bristol ITeC, St Anne's House, St Anne's Road, Bristol BS4 4AB, England. Telephone: (0272) 713481. FRIL Systems launched version 4.0 of FRIL in late 1988.     

Wanted: Dead OR Alive—Ways of Using Problem-structuring Methods in Community OR

Problem structuring has often been seen as providing an appropriate framework for Community OR; from our point of view the question to raise is not how to choose the best method for any particular situation, but how to act on opportunities to use different methods in practice, i.e. making the process the central focus. In this paper we examine our use of problem-structuring methods in the context provided by postmodernist poststructuralist ideas in some Community OR (COR) case studies. In particular this paper will:

• • scrutinise the notion of 'problem' and suggest that it might open a larger space for action and choice to recast this in terms of issues;

• • show the applicability of issue-structuring methods in combination with other participatory methods, e.g. rapid appraisal and action methods, especially in the context of evaluation, which most of our case studies will be concerned with;

• • illustrate the possibilities of mixing and matching different parts of different issue structuring methods in practice.

In this way we demonstrate some ways in which the practice of OR can be revitalised, in particular through a re-conceptualisation of the notion of 'praxis'.     

英文摘要

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英文摘要

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System LS: A Three-Tiered Nonmonotonic Reasoning System

In this paper, a formal system of nonmonotonic reasoning is developed, which takes as its inspiration the manner in which some people make logically justifiable conclusions about nonmonotonic reasoning problems. The people, when asked about individuals, compare the logical strength of the arguments relating any sets to which the individual belongs, to other sets. A three-tiered system of rules including rules of System P as well as Transitivity and Monotonicity is developed. The system, known as System LS for logical strength, deals with three levels of non-strict relationships:

• α ₁β  α are normally β ( more than half of the α are β ) ;

       
  
  

Linearized oscillations of first-order nonlinear neutral delay difference equations

In this paper, we establish an equivalence of oscillation for the first-order nonlinear neutral delay difference equation

and its corresponding linear equation

under weaker conditions on f_i.     

Asymptotic expansions of Hankel transforms of functions with logarithmic singularities

Asymptotic expansions as λ → +∞ are obtained for the Hankel transform

whereJ_v(t) is the Bessel function of the first kind and v is a fixed complex number. The function \tf(t) is allowed to have an asymptotic expansion near the origin of the form

Here, Re _n ↑ +∞ and β_n is an arbitrary complex number.     

Some generalised radiation field integrals

In this paper, two families of integrals that are generalisations of the radiation field integrals are considered:

and

where μ, ν, λ and λ' are arbitrary constants except that ν ≠ 0, −1, −2,…, and ø(μ,ν;x) is the confluent hypergeometric function of the first kind. They are expressed in the form of an infinite series and the corresponding coefficients are evaluated. Some particular cases are mentioned. Algorithms for the tabulation of these integrals are developed and tables (with better precision than those available in the literature) for numerical values have been obtained for some parameter values.     

Oscillatory property of higher order nonlinear difference equations

In this paper, we study the oscillatory and asymptotic behaviour of solutions of higher order nonlinear difference equations of the form

We obtain some necessary and sufficient conditions for all bounded solutions of (*) to be oscillatory and for (*) to have a nonoscillatory solution of a special form.     

New oscillation criteria for first-order delay difference equations

In this paper, some new oscillation criteria are obtained for the first-order delay difference equation

, where k,l₁,l₂,, l_s are positive integer numbers, f is a function. Our results improve the known results in the literature. And some examples are given to demonstrate the advantage of our results.     

Time-Minimal Control of Dissipative Two-Level Quantum Systems: The Generic Case

The objective of this article is to complete preliminary results from , concerning the time-minimal control of dissipative two-level quantum systems whose dynamics is governed by the Lindblad equation. The extremal system is described by a 3-D-Hamiltonian depending upon three parameters. We combine geometric techniques with numerical simulations to deduce the optimal solutions.      

A new way of counting n

In this paper, we shall give a combinatorial proof of the following equation:

,

where m and n are positive integers, m ≤ n, and k₁, k₂, …, k_n-1 are nonnegative integers.     

An improved solution technique for large economic models with consistent expectations

Rational expectations, when applied to the large macro-economic models, implies that the expectation of a variable must be the same as the eventual model forecast of that variable. This has presented large model users with some particular problems as the traditional model solution techniques are not capable of solving such models. Currently two different approaches have been used to solve this problem. These are described by [4] and [1].

This note describes the technique which has been implemented as part of the National Institute's model solution software (NIMODEL); the technique is a simple extension of the traditional Gauss-Seidel solution technique; it appears to offer a considerable increase in efficiency and reliability.     

High-Pitch Formant Estimation by Exploiting Temporal Change of Pitch

This paper considers the problem of obtaining an accurate spectral representation of speech formant structure when the voicing source exhibits a high fundamental frequency. Our work is inspired by auditory perception and physiological studies implicating the use of pitch dynamics in speech by humans. We develop and assess signal processing schemes aimed at exploiting temporal change of pitch to address the high-pitch formant frequency estimation problem. Specifically, we propose a 2-D analysis framework using 2-D transformations of the time–frequency space. In one approach, we project changing spectral harmonics over time to a 1-D function of frequency. In a second approach, we draw upon previous work of Quatieri and Ezzat , , with similarities to the auditory modeling efforts of Chi , where localized 2-D Fourier transforms of the time–frequency space provide improved source-filter separation when pitch is changing. Our methods show quantitative improvements for synthesized vowels with stationary formant structure in comparison to traditional and homomorphic linear prediction. We also demonstrate the feasibility of applying our methods on stationary vowel regions of natural speech spoken by high-pitch females of the TIMIT corpus. Finally, we show improvements afforded by the proposed analysis framework in formant tracking on examples of stationary and time-varying formant structure.      

Conceptual indexing and active retrieval of video for interactive learning environments

Selecting an instructive story from a video case base is an information retrieval problem, but standard indexing and retrieval techniques [1] were not developed with such applications in mind. The classical model assumes a passive retrieval system queried by interested and well-informed users. In educational situations, students cannot be expected to form appropriate queries or to identify their own ignorance. Systems that teach must, therefore, be active retrievers that formulate their own retrieval cues and reason about the appropriateness of intervention.

The Story Producer for InteractivE Learning (SPIEL) is an active retrieval system for recalling stories to tell to students who are learning social skills in a simulated environment [2, 3]. SPIEL is a component of the Guided Social Simulation (GuSS) architecture [4] used to build YELLO, a program that teaches account executives the fine points of selling Yellow Pages advertising. SPIEL uses structured, conceptual indices derived from research in case-based reasoning [5, 6]. SPIEL's manually-created indices are detailed representations of what stories are about, and they are needed to make precise assessments of stories' relevance.

SPIEL's opportunistic retrieval architecture operates in two phases. During the storage phase, the system uses its educational knowledge encapsulated in a library of “storytelling strategies” to determine, for each story, what an opportunity to tell that story would look like. During the retrieval phase, the system tries to recognize those opportunities while the student interacts with the simulation. This design is similar to “opportunistic memory” architectures proposed for opportunistic planning [7, 8].     

Stability for first order delay dynamic equations on time scales

In this paper, we establish some sufficient conditions for the uniform stability and the uniformly asymptotical stability of the first order delay dynamic equation

where is a time scale, p(.) is rd-continuous and positive, the delay function . Our results unify the corresponding ones for differential and difference equations. To the best of our knowledge, this is the first time to discuss the asymptotical behavior of delay dynamic equations on time scales.     

Eigenvalue of fourth-order -point boundary value problem with derivatives

This paper deals with the existence of positive solutions for the fourth-order nonlinear ordinary differential equation

subject to the boundary conditions:

where ,β,γ,δ≥0 are constants such that ρ=δ+γ+βδ>0, and . By means of a fixed-point theorem due to Krasnaselskii, some new existence results of positive solutions for the above multi-point boundary value problem are obtained, which improve the main results of Graef et al. [J.R. Graef, C. Qian, B. Yang, A three-point boundary value problem for nonlinear fourth-order differential equations, J. Math. Anal. Appl. 287 (2003) 217–233]. An example is given to demonstrate the main results of this paper.     

Edge coloring of bipartite graphs with constraints

A classical result from graph theory states that the edges of an l-regular bipartite graph can be colored using exactly l colors so that edges that share an endpoint are assigned different colors. In this paper, we study two constrained versions of the bipartite edge coloring problem.

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