摘要:

In a discourse the hearer must recognize the response intended by the speaker. To perform this recognition, the hearer must ascertain what plans the speaker is undertaking and how the utterances in the discourse further that plan. To do so, the hearer can parse the initial intentions (recoverable from the utterance) and recognize the plans the speaker has in mind and intends the hearer to know about. This paper reports on a theory of parsing the intentions in discourse. It also discusses the role of another aspect of discourse, discourse markers, that are valuable to intended response recognition.

ISSN:0824-7935    

DOI:10.1111/j.1467-8640.1985.tb00054.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

We focus on McCarthy's method of predicate circumscription in order to establish various results about its consistency, and about its ability to conjecture new information. A basic result is that predicate circumscription cannot account for the standard kinds of default reasoning. Another is that predicate circumscription yields no new information about the equality predicate. This has important consequences for the unique names and domain closure assumptions.

ISSN:0824-7935    

DOI:10.1111/j.1467-8640.1985.tb00055.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The so‐called “first generation” expert systems were rule‐based and offered a successful framework for building applications systems for certain kinds of tasks. Spatial, temporal, and causal reasoning, knowledge abstractions, and structuring are among topics of research for “second generation” expert systems. It is proposed that one of the keys for such research isknowledge organization.Knowledge organization determines control structure design, explanation and evaluation capabilities for the resultant knowledge base, and has strong influence on system performance. We are exploring a framework for expert system design that focuses on knowledge organization, for a specific class of input data, namely, continuous, time‐varying data (image sequences or other signal forms). Such data are rich in temporal relationships as well as temporal changes of spatial relations, and are thus a very appropriate testbed for studies involving spatio‐temporal reasoning. In particular, the representation formalism specifies the semantics of the organization of knowledge classes along the relationships of generalization/specialization, decomposition/aggregation, temporal precedence, instantiation, and expectation‐activated similarity. Á hypothesize‐and‐test control structure is driven by the class organizational principles, and includes several interacting dimensions of search (data‐driven, model‐driven, goal‐driven temporal, and failure‐driven search). The hypothesis ranking scheme is based on temporal cooperative computation, with hypothesis “fields of influence” being defined by the hypothesis’ organizational relationships. This control structure has proven to be robust enough to handle a variety of interpretation tasks for continuous temporal data. A particular incarnation, the ALVEN system, for left ventricular performance assessment from X‐ray image seque

ISSN:0824-7935    

DOI:10.1111/j.1467-8640.1985.tb00056.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

In real‐world domains (e.g., a mobile robot environment), things do not always proceed as planned, so it is important to develop better execution‐monitoring techniques and replanning capabilities. This paper describes these capabilities in the SIPE (System for Interactive Planning and Execution Monitoring) planning system. The motivation behind SIPE is to place enough limitations on the representation so that planning can be done efficiently, while retaining sufficient power to still be useful. This work assumes that new information given to the execution monitor is in the form of predicates, thus avoiding the difficult problem of how to generate these predicates from information provided by sensors.The replanning module presented here takes advantage of the rich structure of SIPE plans and is intimately connected with the planner, which can be called as a subroutine. This allows the use of SIPE's capabilities to determine efficiently how unexpected events affect the plan being executed and, in many cases, to retain most of the original plan by making changes in it to avoid problems caused by these unexpected events. SIPE is also capable of shortening the original plan when serendipitous events occur. A general set of replanning actions is presented along with a general replanning capability that has been implemented by using these acti

ISSN:0824-7935    

DOI:10.1111/j.1467-8640.1985.tb00057.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

From the mid‐1950's to the present the notion of a heuristic has played a crucial role in the AI researchers’ descriptions of their work. What has not been generally noticed is that different researchers have often applied the term to rather different aspects of their programs. Things that would be called a heuristic by one researcher would not be so called by others. This is because many heuristics embody a variety of different features, and the various researchers have emphasized different ones of these features as being essential to being a heuristic. This paper steps back from any particular research program and investigates the question of what things, historically, have been thought to be central to the notion of a heuristic and which ones conflict with others. After analyzing the previous definitions and examining current usage of the term, a synthesizing definition is provided. The hope is that with this broader account of ‘heuristic’ in hand, researchers can benefit more fully from the insights of others, even if those insights are couched in a somewhat alien voc

ISSN:0824-7935    

DOI:10.1111/j.1467-8640.1985.tb00058.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

To plan means reasoning about possible actions, but a robot must also reason about actual events. This paper proposes a formal theory about actual and possible events. It presents a new modal logic as a notation for this theory and a technique for planning in the modal logic using a first‐order theorem prover augmented with simple modal reasoning. This avoids the need for a general modal‐logic theorem prover. Adding beliefs to this theory raises an interesting problem for which the paper offers a tentative solut

ISSN:0824-7935    

DOI:10.1111/j.1467-8640.1985.tb00059.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The central problem in vision is to determine scene properties from image properties. This is difficult because the problem, formally posed, is underconstrained. Methods that infer scene properties from images make assumptions about how the world determines what we see. In remote sensing, some of these assumptions can be dealt with explicitly. Available scene knowledge, in the form of a digital terrain model and a ground cover map, is used to synthesize an image for a given date and time. The synthesis process assumes that the surface is a perfectly diffuse or “lambertian” reflector. A scene radiance equation is described based on simple models of direct solar irradiance, diffuse sky irradiance, and atmospheric path radiance. Parameters of the model are estimated from the real image. A statistical comparison of the real image and the synthetic image is used to judge how well the model represents the mapping from scene to image.The methods presented for image synthesis are similar to those used in computer graphics. The motivation, however, is different. In graphics, the goal is to produce an effective rendering of the scene for a human viewer. Here, the goal is to predict properties of real images. In vision, one must deal with a confounding of effects due to surface shape, surface material, illumination, shadows, and atmosphere. These effects often detract from, rather than enhance, the determination of invariant scene characterist

ISSN:0824-7935    

DOI:10.1111/j.1467-8640.1985.tb00060.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Axiom sets and their extensions are viewed as functions from the set of formulas in the language to a set of four truth values,t, f, ufor undefined, andkfor contradiction. Such functions form a lattice with “contains less information” as the partial order ?, and “combination of several sources of knowledge” as the least‐upper‐bound operation ⊔. Inference rules are expressed as binary relations between such functions. We show that the usual criterium on fixpoints, namely, to be minimal, does not apply correctly in the case of non‐monotonic inference rules. A stronger concept, approachable fixpoints, is introduced and proven to be sufficient for the existence of a derivation of the fixpoint. In addition, the usefulness of our approach is demonstrated by concise proofs for some previously known results about norma

ISSN:0824-7935    

DOI:10.1111/j.1467-8640.1985.tb00061.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Several computational theories of early visual processing, such as Marr's zero‐crossing theory, are biologically motivated and based largely on the well‐known difference of Gaussians (DOG) receptive‐field model of retinal processing. We examine the physiological relevance of the DOG, particularly in the light of evidence indicating significant spatiotemporal inseparability in the behaviour of retinal cell types. From the form of the inseparability we find that commonly accepted functional interpretations of retinal processing based on the DOG, such as the Laplacian of a Gaussian and zero crossings, are not valid for time‐varying images. In contrast to current machine‐vision approaches, which attempt to separate form and motion information at an early stage, it appears that this is not the case in biological systems. It is further shown that the qualitative form of this inseparability provides a convenient precursor to the extraction of both form and motion information. We show the construction of efficient mechanisms for the extraction of orientation and two‐dimensional normal velocity through the use of a hierarchical computational framework. The resultant mechanisms are well localized in space‐time and can be easily tuned to various degrees of orientation and spee

ISSN:0824-7935    

DOI:10.1111/j.1467-8640.1985.tb00062.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

This paper describes a first attempt to base a paraphrase generation system upon Meľčuk and Žolkovskij's linguistic meaning‐text (MT) model whose purpose is to establish correspondences between meanings, represented by networks, and (ideally) all synonymous texts having this meaning. The system described here contains a Prolog implementation of a small explanatory and combinatorial dictionary (the MT lexicon) and, using unification and backtracking, generates from a given network the sentences allowed by the dictionary and the lexical transformations of the model. The passage from a net to the final texts is done through a series of transformations of intermediary structures that closely correspond to MT utterance representations (semantic, deep‐syntax, surface‐syntax, and morphological representations). These are graphs and trees with labeled arcs. The Prolog unification (equality predicate) was extended to extract information from these representations and build new ones. The notion of utterance path, used by many authors, is replaced by that ofcovering by defining sub

ISSN:0824-7935    

DOI:10.1111/j.1467-8640.1985.tb00063.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY