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1.
No work is inherently either visible or invisible. We always see work through a selection of indicators: straining muscles, finished artifacts, a changed state of affairs. The indicators change with context, and that context becomes a negotiation about the relationship between visible and invisible work. With shifts in industrial practice these negotiations require longer chains of inference and representation, and may become solely abstract.This article provides a framework for analyzing invisible work in CSCW systems. We sample across a variety of kinds of work to enrich the understanding of how invisibility and visibility operate. Processes examined include creating a non-person in domestic work; disembedding background work; and going backstage. Understanding these processes may inform the design of CSCW systems and the development of related social theory. 相似文献
2.
Masakazu Nasu 《Theory of Computing Systems》1979,13(1):81-93
Indecomposable local maps of one-dimensional tessellation automata are studied. The main results of this paper are the following. (1) For any alphabet containing two or more symbols and for anyn 1, there exist indecomposable scope-n local maps over . (2) If is a finite field of prime order, then a linear scope-n local map over is indecomposable if and only if its associated polynomial is an irreducible polynomial of degreen – 1 over , except for a trivial case. (3) Result (2) is no longer true if is a finite field whose order is not prime. 相似文献
3.
The relation between an operational interleaving semantics forTSCP based on a transition system and a compositional true concurrency semantics based on event structures is studied. In particular we extend the consistency result of Goltz and Loogan [15] forTCSP processes without recursion to the general case. Thus we obtain for everyTCSP processP that its operational meaningO(P) and the interleaving behaviourO( M3P3) which is derived from the event structureM3P3 associated withP are bisimilar. 相似文献
4.
We give an O(k · n2) fixed parameter tractable algorithm for the
1-Sided Crossing Minimization. The constant in the running time is the golden ratio
= (1+5)/2 1.618. The constant k is the parameter of the
problem: the number of allowed edge crossings. 相似文献
5.
Our starting point is a definition of conditional event EH which differs from many seemingly similar ones adopted in the relevant literature since 1935, starting with de Finetti. In fact, if we do not assign the same third value u (undetermined) to all conditional events, but make it depend on EH, it turns out that this function t(EH) can be taken as a general conditional uncertainty measure, and we get (through a suitable – in a sense, compulsory – choice of the relevant operations among conditional events) the natural axioms for many different (besides probability) conditional measures. 相似文献
6.
J. Roger Hindley 《Formal Aspects of Computing》1992,4(5):470-486
This paper is an informal introduction to the theory of types which use a connective for the intersection of two types and a constant for a universal type, besides the usual connective for function-types. This theory was first devised in about 1977 by Coppo, Dezani and Sallé in the context of-calculus and its main development has been by Coppo and Dezani and their collaborators in Turin. With suitable axioms and rules to assign types to-calculus terms, they obtained a system in which (i) the set of types given to a term does not change under-conversion, (ii) some interesting sets of terms, for example the solvable terms and the terms with normal form, can be characterised exactly by the types of their members, and (iii) the type-apparatus is not so complex as polymorphic systems with quantifier-containing types and therefore probably not so expensive to implement mechanically as these systems.There are in fact several variant systems with different detailed properties. This paper defines and motivates the simplest one from which the others are derived, and describes its most basic properties. No proofs are given but the motivation is shown by examples. A comprehensive bibliography is included. 相似文献
7.
Stephen J. Hegner 《Annals of Mathematics and Artificial Intelligence》1993,7(1-4):129-195
The classical theory of acyclicity of universal relational schemata identifies a set of desirable properties of such schemata, and then shows that all of these properties are equivalent to one another, and in turn equivalent to certain acyclicity characterizations of a hypergraph underlying the schema. The desirable properties include the simplicity of constraints, the correctness of certain efficient query evaluation algorithms, and the complexity of maintaining the integrity of a decomposed database. The principal result of this paper is to show that the essence of this result may be extended to a much more general setting; namely, that in which database schemata are just sets and database mappings just functions. Rather than identifying a single desirability class, our work shows that there are several, all of which collapse to a common group when restricted to the universal relational setting. Particularly, the classical notions of pairwise consistency implies global consistency and hypergraph acyclicity are not equivalent in the general case, but rather are independent of each other, and may be considered separately or in combination, to yield varying strengths of desirability. 相似文献
8.
Im Teil II Bildung von Elementarsätzen wird der Teil Namengebung und Kennzeichnung vorbereitet. Seine Überschrift könnte auch lauten: Was sind Nominatoren und wie kommen sie zustande? Teil V ist wie seine Vorgänger Teil III Gleichheit und Abstraktion und Teil IV Objektsprache/Metasprache als eine Erweiterung einer rationalen Grammatik aufzufassen. Der noch folgende Teil VI Logik und Geltungsicherung von Behauptungen schließt die Serie Informatik als Grundbildung ab. 相似文献
9.
Dr. T. Ström 《Computing》1972,10(1-2):1-7
It is a commonly occurring problem to find good norms · or logarithmic norms (·) for a given matrix in the sense that they should be close to respectively the spectral radius (A) and the spectral abscissa (A). Examples may be the certification thatA is convergent, i.e. (A)A<1 or stable, i.e. (A)(A)<0. Often the ordinary norms do not suffice and one would like to try simple modifications of them such as using an ordinary norm for a diagonally transformed matrix. This paper treats this problem for some of the ordinary norms.
Minimisierung von Normen und Logarithmischen Normen durch Diagonale Transformationen
Zusammenfassung Ein oft vorkommendes praktisches Problem ist die Konstruktion von guten Normen · und logarithmischen Normen (·) für eine gegebene MatrixA. Mit gut wird dann verstanden, daß A den Spektralradius (A)=max |1| und (A) die Spektralabszisse (A)=max Re i gut approximieren. Beispiele findet man für konvergente Matrizen wo (A)A<1 gewünscht ist, und für stabile Matrizen wo (A)(A)<0 zu zeigen ist. Wir untersuchen hier, wie weit man mit Diagonaltransformationen und dengewöhnlichsten Normen kommen kann.相似文献
10.
Let (X, #) be an orthogonality space such that the lattice C(X, #) of closed subsets of (X, #) is orthomodular and let (, ) denote the free orthogonality monoid over (X, #). Let C0(, ) be the subset of C(, ), consisting of all closures of bounded orthogonal sets. We show that C0(, ) is a suborthomodular lattice of C(, ) and we provide a necessary and sufficient condition for C0(, ) to carry a full set of dispersion free states.The work of the second author on this paper was supported by National Science Foundation Grant GP-9005. 相似文献
11.
Rainer Kuhlen 《Computers and the Humanities》1991,25(2-3):93-101
This paper discusses terms which are of mutual importance to the fields of information science and computer science. Specifically we discuss the notions of information and knowledge: their interrelationships as well as their differences, and the concept of value-adding. Concrete examples are used in the discussion.Rainer Kuhlen is professor of Information Science at the University of Konstanz. 相似文献
12.
Piero Pagliani 《Journal of Logic, Language and Information》1997,6(1):63-99
Semantics connected to some information based metaphor are well-known in logic literature: a paradigmatic example is Kripke semantic for Intuitionistic Logic. In this paper we start from the concrete problem of providing suitable logic-algebraic models for the calculus of attribute dependencies in Formal Contexts with information gaps and we obtain an intuitive model based on the notion of passage of information showing that Kleene algebras, semi-simple Nelson algebras, three-valued ukasiewicz algebras and Post algebras of order three are, in a sense, naturally and directly connected to partially defined information systems. In this way wecan provide for these logic-algebraic structures a raison dêetre different from the original motivations concerning, for instance, computability theory. 相似文献
13.
D. E. Khmelnov 《Programming and Computer Software》2001,27(1):12-17
The basic disadvantage of the algorithms of EG-eliminations [1] is that the degrees of elements of the polynomial matrix being used and the coefficients of these elements grow. The progress in overcoming this difficulty is associated with the use of modular approaches. The paper describes modularization of EG-eliminations and a modified elimination scheme based on that modularization (quasi-modular algorithm). 相似文献
14.
Hans Ulrich Simon 《Acta Informatica》1989,26(8):771-785
Summary Many reductions among combinatorial problems are known in the context of NP-completeness. These reductions preserve the optimality of solutions. However, they may change the relative error of approximative solutions dramatically. In this paper, we apply a new type of reductions, called continuous reductions. When one problem is continuously reduced to another, any approximation algorithm for the latter problem can be transformed into an approximation algorithm for the former. Moreover, the performance ratio is preserved up to a constant factor. We relate the problem Minimum Number of Inverters in CMOS-Circuits, which arises in the context of logic synthesis, to several classical combinatorial problems such as Maximum Independent Set and Deletion of a Minimum Number of Vertices (Edges) in Order to Obtain a Bipartite (Partial) Subgraph. 相似文献
15.
This paper presents algorithms for multiterminal net channel routing where multiple interconnect layers are available. Major improvements are possible if wires are able to overlap, and our generalized main algorithm allows overlap, but only on everyKth (K 2) layer. Our algorithm will, for a problem with densityd onL layers,L K + 3,provably use at most three tracks more than optimal: (d + 1)/L/K + 2 tracks, compared with the lower bound of d/L/K. Our algorithm is simple, has few vias, tends to minimize wire length, and could be used if different layers have different grid sizes. Finally, we extend our algorithm in order to obtain improved results for adjacent (K = 1) overlap: (d + 2)/2L/3 + 5 forL 7.This work was supported by the Semiconductor Research Corporation under Contract 83-01-035, by a grant from the General Electric Corporation, and by a grant at the University of the Saarland. 相似文献
16.
Summary In this paper the notions of L form and its interpretations are introduced to define families of structurally similar L systems. The families of L systems thus defined are studied from a number of different points of view. It is felt that this novel approach will shed new light on many questions concerning L systems. 相似文献
17.
Lionel Snell 《AI & Society》1989,3(3):247-255
This article looks at the broadest implications of public acceptance of AI. A distinction is drawn between conscious belief in a technology, and organic belief where the technology is incorporated into an unconscious world model. The extent to which we feel threatened by AI's apparent denial of spirit is considered, along with a discussion of how people react to this threat. It is proposed that organic acceptance of AI models would lead to a rebirth of popular spiritual concepts as paradoxical as the New Age ideas that have their roots in the theories of physics. Finally the relevance of this speculation is discussed in terms of how it could impinge upon public acceptability of AI technology. 相似文献
18.
Using the results obtained for the one-dimensional case in Part I (Reliable Computing
9(1) (2003), pp. 1–20) of the paper, an analysis of the two-dimensional relational expression a
1 x
1 + a
2 x
2 b, where {, , , =}, is conducted with the help of a midpoint-radius diagram and other auxiliary diagrams. The solution sets are obtained with a simple boundary-line selection rule derived using these tools, and are characterized by types of one-dimensional cuts through the solution space. A classification of basic possible solution types is provided in detail. The generalization of the approach for n-dimensional interval systems and avenues for further research are also outlined. 相似文献
19.
Enhancing the performance of an agent-based manufacturing system through learning and forecasting 总被引:3,自引:0,他引:3
Weiming Shen Francisco Maturana Douglas H. Norrie 《Journal of Intelligent Manufacturing》2000,11(4):365-380
Agent-based technology has been identified as an important approach for developing next generation manufacturing systems. One of the key techniques needed for implementing such advanced systems will be learning. This paper first discusses learning issues in agent-based manufacturing systems and reviews related approaches, then describes how to enhance the performance of an agent-based manufacturing system through learning from history (based on distributed case-based learning and reasoning) and learning from the future (through system forecasting simulation). Learning from history is used to enhance coordination capabilities by minimizing communication and processing overheads. Learning from the future is used to adjust promissory schedules through forecasting simulation, by taking into account the shop floor interactions, production and transportation time. Detailed learning and reasoning mechanisms are described and partial experimental results are presented. 相似文献
20.
Consideration was given to scheduling by the criterion for uniform use of resources. It was assumed that each job is executed by a unit resource. Two types of inter-job dependences were studied: finish–finish (one job cannot be completed until the other is completed) and finish–start (one job cannot be started until the other is not completed). To solve the problem, a geometrical method reducing solution to determining the shortest trajectory in a domain constructed from the network graph was proposed. 相似文献