Context calibration

The basic starting point of this paper is that context constitutes most of the user interface when doing VR-related experiments, but even so one bases performance measures on only a few active tasks. Thus, in order to meaningfully compare results obtained in vastly different experiments one needs to somehow subtract the contribution to observables that are due to the context. For the case where one is investigating whether changes in one observable causes changes in another, a method, context calibration, is proposed that does just that. This method is expected to, to a large extent, factor out the part of one's results that are due to factors that are not explicitly considered when evaluating the experiment, factors that the experimenter might not even suspect influences the experiment. A procedure for systematically investigating the theoretical assumptions underlying context calibration is also discussed as is an initial experiment adhering to the proposed methodology.     

Reduction and unification in lambda calculi with a general notion of subtype

Reduction, equality, and unification are studied for a family of simply typed -calculi with subtypes. The subtype relation is required to relate base types only to base types and to satisfy some order-theoretic conditions. Constants are required to have a least type, that is, no overloading. We define the usual and a subtype-dependent -reduction. These are related to a typed equality relation and shown to be confluent in a certain sense. We present a generic algorithm for preunification modulo -conversion and an arbitrary subtype relation. Furthermore it is shown that unification with respect to any subtype relation is universal.     

The π-Calculus in Direct Style

We introduce a calculus which is a direct extension of both the and the calculi. We give a simple type system for it, that encompasses both Curry's type inference for the -calculus, and Milner's sorting for the -calculus as particular cases of typing. We observe that the various continuation passing style transformations for -terms, written in our calculus, actually correspond to encodings already given by Milner and others for evaluation strategies of -terms into the -calculus. Furthermore, the associated sortings correspond to well-known double negation translations on types. Finally we provide an adequate CPS transform from our calculus to the -calculus. This shows that the latter may be regarded as an assembly language, while our calculus seems to provide a better programming notation for higher-order concurrency. We conclude by discussing some alternative design decisions.     

A predicate transformer for the progress property ‘to-always’

The temporal property to-always has been proposed for specifying progress properties of concurrent programs. Although the to-always properties are a subset of the leads-to properties for a given program, to-always has more convenient proof rules and in some cases more accurately describes the desired system behavior. In this paper, we give a predicate transformerwta, derive some of its properties, and use it to define to-always. Proof rules for to-always are derived from the properties ofwta. We conclude by briefly describing two application areas, nondeterministic data flow networks and self-stabilizing systems where to-always properties are useful.     

Design sensitivity analysis of nonlinear dynamic response of structural and mechanical systems

This paper describes a unified variational theory for design sensitivity analysis of nonlinear dynamic response of structural and mechanical systems for shape, nonshape, material and mechanical properties selection, as well as control problems. The concept of an adjoint system, the principle of virtual work and a Lagrangian-Eulerian formulation to describe the deformations and the design variations are used to develop a unified view point. A general formula for design sensitivity analysis is derived and interpreted for usual performance functionals. Analytical examples are utilized to demonstrate the use of the theory and give insights for application to more complex problems that must be treated numerically.Derivatives The comma notation for partial derivatives is used, i.e. G,_u = G/u. An upper dot represents material time derivative, i.e. ü = ²u/t². A prime implies derivative with respect to the time measured in the reference time-domain, i.e. u = du/d.     

The Implications of an Externalist Theory of Rule-Following Behaviour for Robot Cognition

Given (1) Wittgensteins externalist analysis of the distinction between following a rule and behaving in accordance with a rule, (2) prima facie connections between rule-following and psychological capacities, and (3) pragmatic issues about training, it follows that most, even all, future artificially intelligent computers and robots will not use language, possess concepts, or reason. This argument suggests that AIs traditional aim of building machines with minds, exemplified in current work on cognitive robotics, is in need of substantial revision.     

Random Constraint Satisfaction: Flaws and Structure

A recent theoretical result by Achlioptas et al. shows that many models of random binary constraint satisfaction problems become trivially insoluble as problem size increases. This insolubility is partly due to the presence of flawed variables, variables whose values are all flawed (or unsupported). In this paper, we analyse how seriously existing work has been affected. We survey the literature to identify experimental studies that use models and parameters that may have been affected by flaws. We then estimate theoretically and measure experimentally the size at which flawed variables can be expected to occur. To eliminate flawed values and variables in the models currently used, we introduce a flawless generator which puts a limited amount of structure into the conflict matrix. We prove that such flawless problems are not trivially insoluble for constraint tightnesses up to 1/2. We also prove that the standard models B and C do not suffer from flaws when the constraint tightness is less than the reciprocal of domain size. We consider introducing types of structure into the constraint graph which are rare in random graphs and present experimental results with such structured graphs.     

Artefacts as designed, artefacts as used: resources for uncovering activity dynamics

This paper addresses the use of artefacts as a powerful resource for analysis, focusing on the artefact as designed as a means of eliciting the designers explicit and implicit knowledge and artefacts as used as a means of uncovering the trail left by currently inactive processes. Artefact analysis is particularly suitable in situations where direct observation is ineffective, especially in activities that occur infrequently. We demonstrate the usefulness of our technique through the analysis of artefacts within both the office and the meeting environment. This is part of a wider study aimed at understanding the nature of decisions in meetings with the view of producing a tool to aid decision management and hence reduce rework. We conclude by drawing out some general lessons from our analysis, which reaffirms the intricate role that artefacts play in maintaining activity dynamics.

Constructing the ‘Dossier Représentatif’

This paper analyzes the complex nature of collaboration in hospitals. Information-sharing under different technological regimes and work organizations is examined with special attention to the role of different types of screen-based records. The need for supporting local practices, professional distance and the different world views of the medical and nursing staff and administrators is stressed. Four meanings of information sharing based on the idea of a dossier réprésentatif are explored: (i) a core document of basic patient-related data which is shared by all organizational units and professions; (ii) using the (real time) transfer of data across a distributed environment to strengthen the opportunity for, dialogue; (iii) computer support for browsing through a variety of folders that embed different practices; (iv) a unified dossier shared by a bounded collaborative ensemble.     

A note to the definition of the ŁΠ-algebras

The -algebras are interesting algebraic structures. They were introduced by Esteva, Godo, and Montagna. These algebras are closely related to the well-known MV-algebras and -algebras. They have two sets of operations and reduct to one set is an MV-algebra and to the other one is a -algebra.Other important reducts of -algebras are so-called P-algebras (an MV-algebras enriched with product connective) and -algebras (-algebras with additional involutive negation).The definition of -algebras is based on its MV-algabraic reduct and the additional identities. In this paper we present how to base this definition on the other reducts we mention above. We present minimal sets of conditions which has to be added to the defining conditions of those reducts in order to obtain -algebras.     

Sarcasm,Deception, and Stating the Obvious: Planning Dialogue without Speech Acts

This paper presents an alternative to the speech acts with STRIPS approach to implementing dialogue a fully implemented AI planner which generates and analyses the semantics of utterances using a single linguistic act for all contexts. Using this act, the planner can model problematic conversational situations, including felicitous and infelicitous instances of bluffing, lying, sarcasm, and stating the obvious. The act has negligible effects, and its precondition can always be proved. Speaker maxims enable the speaker to plan to deceive, as well as to generate implicatures, while hearer maxims enable the hearer to recognise deceptions, and interpret implicatures. The planner proceeds by achieving parts of the constructive proof of a goal. It incorporates an epistemic theorem prover, which embodies a deduction model of belief, and a constructive logic.     

On a random Volterra integral equation

Summary Tsokos [12] showed the existence of a unique random solution of the random Volterra integral equation (*)x(t; ) = h(t; ) + _o ^t k(t, ; )f(, x(; )) d, where , the supporting set of a probability measure space (,A, P). It was required thatf must satisfy a Lipschitz condition in a certain subset of a Banach space. By using an extension of Banach's contraction-mapping principle, it is shown here that a unique random solution of (*) exists whenf is (, )-uniformly locally Lipschitz in the same subset of the Banach space considered in [12].     

Alternative human role in manufacturing

The limits of Taylorism are alive and well in today's manufacturing systems. Automation does have to constrain human ability creativity, judgement and skill, and undermine human dignity. The paper presents an interactive concept of manufacturing. Human-Oriented Manufacturing Systems (HOMS), which aims to achieve high flexibility and quality of production while creating an environment for happy working and joyful living.Presented at conference on Ecology of Science and Technology, Japan Science Foundation, Tokyo, 1992.     

An operational model for structuring the requirements generation process

Product quality is directly related to how well that product meets the customers needs and intents. Therefore, the ability to capture customer requirements correctly and succinctly is paramount. Unfortunately, within most software development frameworks requirements elicitation, recording and evaluation are some of the more ill-defined and least structured activities. To help address such inadequacies, we propose a requirements generation model (RGM) that (a) decomposes the conventional requirements analysis phase into sub-phases which focus and refine requirement generation activities, (b) bounds and structures those activities to promote a more effective generation process, and (c) implements a monitoring methodology to assist in detecting deviations from well-defined procedures intended to support the generation of requirements that meet the customers intent. The RGM incorporates lessons learned from a preliminary study that concentrated on identifying where and how miscommunication and requirements omission occur. An industry study (also reported in this paper) attests to the effectiveness of the RGM. The results of that study indicate that the RGM helps (a) reduce the late discovery of requirements, (b) reduce the slippage in milestone completion dates, and (c) increase customer and management satisfaction levels.     

Coordinating Multiple Agents via Reinforcement Learning

In this paper, we attempt to use reinforcement learning techniques to solve agent coordination problems in task-oriented environments. The Fuzzy Subjective Task Structure model (FSTS) is presented to model the general agent coordination. We show that an agent coordination problem modeled in FSTS is a Decision-Theoretic Planning (DTP) problem, to which reinforcement learning can be applied. Two learning algorithms, coarse-grained and fine-grained, are proposed to address agents coordination behavior at two different levels. The coarse-grained algorithm operates at one level and tackle hard system constraints, and the fine-grained at another level and for soft constraints. We argue that it is important to explicitly model and explore coordination-specific (particularly system constraints) information, which underpins the two algorithms and attributes to the effectiveness of the algorithms. The algorithms are formally proved to converge and experimentally shown to be effective.     

Extremal Relations between Additive Loss Functions and the Kolmogorov Complexity

Conditions are presented under which the maximum of the Kolmogorov complexity (algorithmic entropy) K(₁... _N ) is attained, given the cost f( _i ) of a message ₁... _N . Various extremal relations between the message cost and the Kolmogorov complexity are also considered; in particular, the minimization problem for the function f( _i ) – K(₁... _N ) is studied. Here, is a parameter, called the temperature by analogy with thermodynamics. We also study domains of small variation of this function.     

Comparative complexity of the representation of languages by probabilistic automata

We analyze the effect of the degree of isolation of a cut point on the number of states P(U, ) of a probabilistic automaton representing the language U. We give an example of a language Uⁿ consisting of words of length n such that there exist numbers < for which P(Uⁿ, )/P(Uⁿ, )0 as n.Translated from Kibernetika, No. 3, pp. 21–25, May–June, 1989.     

Implementing the ‘Fool's model’ of combinatory logic

This paper studies Fool's models of combinatory logic, and relates them to Hindley's D-completeness problem. A fool's model is a family of sets of formulas, closed under condensed detachment. Alternatively, it is a model ofCL in naive set theory. We examine Resolution; and the P-W problem. A sequel shows T is D-complete; also, its extensions. We close with an implementation FMO of these ideas.     

On the capabilities of systolic systems

This paper studies transformations of systems into systolic systems with related functionality. It distinguishes two antithetical transformation methods: one syntactic, the other semantic.The syntactic method considers the topology of the system, but ignores its behavior and the behavior of its combinational units. We use retiming and introduce two new basic syntactic techniques: tiling and bypassing. Using these, we present syntactic transformations that perform the following: conversion of a semisystolic system to a systolic one; elimination of either broadcast or instant-accumulation from a system that is otherwise systolic; and speeding up a systolic system by any constant factor. Leiserson and Saxe [10] have developed transformations to accomplish the first two tasks, but failed to preserve the behavior of the system. Our transformations leave the behavior of the system intact.The semantic method considers the functionality of the system as a whole, but ignores its internal structure. A system is called -homogeneous if all its combinational units are identical and equal to the given unit . We show that every semisystolic system can be transformed into a -homogeneous systolic system, where depends only on the alphabet used by the system to communicate with the external world. As a special case, any regular language L ^* is defined by some -homogeneous systolic system, where depends only on .For binary systems, this technique produces a systolic system with a feasible clock period ofO(i + log(o)), wherei ando are the numbers of input and output ports of the system. This clock period is independent of the size and complexity of the given system.Part of this work was done while the authors were with Bellcore, 445 South Street, Morristown, NJ 07960-1910, USA.     

Almost surely continuous solutions of a nonlinear stochastic integral equation

A nonlinear stochastic integral equation of the Hammerstein type in the formx(t; ) = h(t, x(t; )) + _s k(t, s; )f(s, x(s; ); )d(s) is studied wheret S, a measure space with certain properties, , the supporting set of a probability measure space (,A, P), and the integral is a Bochner integral. A random solution of the equation is defined to be an almost surely continuousm-dimensional vector-valued stochastic process onS which is bounded with probability one for eacht S and which satisfies the equation almost surely. Several theorems are proved which give conditions such that a unique random solution exists. AMS (MOS) subject classifications (1970): Primary; 60H20, 45G99. Secondary: 60G99.