Showing papers on "Representation (systemics) published in 1996"

Local feature analysis: a general statistical theory for object representation

Abstract: Low-dimensional representations of sensory signals are key to solving many of the computational problems encountered in high-level vision. Principal component analysis (PCA) has been used in the pa...

Part-whole relations in object-centered systems: an overview

Abstract: Knowledge bases, data bases and object-oriented systems (referred to in the paper as Object-Centered systems) all rely on attributes as the main construct used to associate properties to objects; among these, a fundamental role is played by the so-called part-whole relation. The representation of such structural information usually requires particular semantics together with specialized inference and update mechanisms, but rarely do current modelling formalisms and methodologies give it a specific, ‘first-class’ dignity. The main thesis of this paper is that the part-whole relation cannot simply be considered as an ordinary attribute: its specific ontological nature requires to be understood and integrated within data-modelling formalisms and methodologies. On the basis of such an ontological perspective, we survey the conceptual modelling issues involving part-whole relations, and the various modelling frameworks provided by knowledge representation and object-oriented formalisms.

Method and system for digital plenoptic imaging

Abstract: A computer-based method and system for digital 3-dimensional imaging of an object which allows for viewing images of the object from arbitrary vantage points. The system, referred to as the Lumigraph system, collects a complete appearance of either a synthetic or real object (or a scene), stores a representation of the appearance, and uses the representation to render images of the object from any vantage point. The appearance of an object is a collection of light rays that emanate from the object in all directions. The system stores the representation of the appearance as a set of coefficients of a 4-dimensional function, referred to as the Lumigraph function. From the Lumigraph function with these coefficients, the Lumigraph system can generate 2-dimensional images of the object from any vantage point. The Lumigraph system generates an image by evaluating the Lumigraph function to identify the intensity values of light rays that would emanate from the object to form the image. The Lumigraph system then combines these intensity values to form the image.

Origins and early development of perception, action, and representation

Abstract: Research relevant to the origins and early development of two functionally dissociable perceptual systems is summarized. One system is concerned with the perceptual control and guidance of actions, the other with the perception and recognition of objects and events. Perceptually controlled actions function in real time and are modularly organized. Infants perceive where they are and what they are doing. By contrast, research on object recognition suggests that even young infants represent some of the defining features and physical constraints that specify the identity and continuity of objects. Different factors contribute to developmental changes within the two systems; it is difficult to generalize from one response system to another; and neither perception, action, nor representation qualifies as ontogenetically privileged. All three processes develop from birth as a function of intrinsic processing constraints and experience.

System and method for interactively transforming a system or process into a visual representation

Abstract: A computerized modeling system is provided. The present invention is a computer-implemented, interactive, real-time software tool, for physically transforming a system or process into a visual representation. The software tool includes a class developer for interactively developing the visual representation in real time. The visual representation is physically embodied in a computer-readable medium for visualization on a computer display device, and includes at least one of a class, a class behavior, a class attribute, a collaboration, and a collaboration message flow. The software tool also includes a three-dimensional visual representation module for displaying a three-dimensional depiction of the visual representation on the display device.

Using fontless structured document image representations to render displayed and printed documents at preferred resolutions

Abstract: A method in which first and second representations of a document are provided, for example, by being made available on one or more server computers connected to a computer network, such as the Internet or a corporate intranet. The first and second representations are resolution-dependent structured representations and have, respectively, first and second characteristic resolutions, the second resolution being greater than the first. The first representation, but not the second, is provided in digital form to an untrusted recipient. For example, the first representation can be transmitted through the network from the server on which the first representation is available to a client computer connected to the network. The second representation is converted to a third representation of the document, the third representation being a representation in a human-readable, nondigital form. For example, the second representation can be transmitted through the network in a secure manner to a trusted printing facility connected to the network. The trusted facility can then produce the third representation, for example by printing a hardcopy representation of the document. Finally, the third representation, but not the second, is provided to the untrusted recipient, for example, by physically transferring the third representation to the untrusted recipient.

Scale-Space : A Framework for Handling Image Structures at Multiple Scales

Abstract: This article gives a tutorial overview of essential components of scale-space theory --- a framework for multi-scale signal representation, which has been developed by the computer vision community to analyse and interpret real-world images by automatic methods.

Picture similarity retrieval using the 2D projection interval representation

Abstract: Spatial relationships are important ingredients for expressing constraints in retrieval systems for pictorial or multimedia databases. We have proposed a unified representation for spatial relationships, 2D Projection Interval Relationships (2D-PIR), that integrates both directional and topological relationships. We develop techniques for similarity retrieval based on the 2D-PIR representation, including a method for dealing with rotated and reflected images.

$L^2$ solvability and representation by caloric layer potentials in time-varying domains

Abstract: We consider boundary value problems for the heat equation in time varying graph domains of the form Ω = {(x0, x, t) ∈ IR × IRn−1 × IR : x0 > A(x, t) }, obtaining solvability of the Dirichlet and Neumann problems when the data lies in L(∂Ω). We also prove optimal regularity estimates for solutions to the Dirichlet problem when the data lies in a parabolic Sobolev space of functions having a tangential (spatial) gradient, and 1/2 of a time derivative in L(∂Ω). Furthermore, we obtain representations of our solutions as caloric layer potentials. We prove these results for functions A(x, t) satisfying a minimal regularity condition which is essentially sharp from the point of view of the related singular integral theory. We construct counter examples which show that our results are in the nature of “ best possible. ” 1991 Mathematics Subject Classification. Primary 42B20, 35K05. keywords and phrases. heat equation, Dirichlet problem, Neumann problem, layer potentials, timevarying domains, singular integrals, Rellich inequalities. 1 Supported by an NSF Grant 0. Background and Notation. A longstanding problem concerning solvability of the Dirichlet problem for Laplace’s equation in a Lipschitz domain was resolved by B. Dahlberg [D1], who showed that in such domains harmonic measure, dω, and surface measure, dσ, are mutually absolutely continuous, and furthermore, that the Dirichlet problem is solvable with data in L(dσ) (and consequently with data in L, 2− < p <∞). R. Hunt proposed the problem of finding an analogue of Dahlberg’s result for the heat equation in domains whose boundaries are given locally as graphs of functions A(x, t) which are Lipschitz in the space variable. It was conjectured at one time that A should be Lip 1 2 in the time variable, but subsequent counterexamples of Kaufmann and Wu [KW] showed that this condition does not suffice. Motivated in part by work of Strichartz [Stz] on BMO Sobolev spaces, and in part by work of M. Murray [Mu], Lewis and Murray [LM], made significant progress toward a solution of Hunt’s question, by establishing mutual absolute continuity of caloric measure and a certain parabolic analogue of surface measure in the case that A has 1 2 of a time derivative in BMO(IR) on rectangles, a condition only slightly stronger than Lip 1 2 . Furthermore these authors obtained solvability of the Dirichlet problem with data in L, for p sufficiently large, but unspecified. The regularity condition which Lewis and Murray imposed upon A(x, t) (or, to be more precise, an equivalent formulation of it) was shown by the first named author to be necessary and sufficient for L boundedness of the first parabolic Calderón commutator, thus further clarifying the connection between the results of [LM] and those of [D1]. Still, by analogy to [D1], it remained an open problem to treat the case of boundary value problems with L data in the parabolic setting. It is this issue of L solvability that we address here. To be more specific in this paper we study the Dirichlet and Neumann problems for the heat equation in non cylindrical (i.e. time-varying) graph domains. We treat each of these problems in the case that the data belongs to L with respect to a certain projective Lebesgue measure. We 1 also consider regularity estimates for solutions of the Dirichlet problem when the data belongs to a parabolic Sobolev space having a full spatial derivative and one half of a time derivative in L. Existence of our solutions will be obtained by using the method of layer potentials. In addition we shall give an alternate, simpler proof of recent results of the first author [H2] concerning “ smoothing operators of Calderòn type, ” including the caloric single layer potential. We shall study these problems in graph domains of the form Ω = {(x0, x, t) ∈ IR× IRn−1 × IR : x0 > A(x, t) } (0.1) where n ≥ 2 and A(x, t) is Lipschitz in the space variable, uniformly in time, i.e., |A(x, t)− A(y, t)| ≤ β0 |x− y|, x, y ∈ IRn−1, t ∈ IR, (0.2) and where A(x, t) satisfies a certain half order smoothness condition in the time variable. To describe this condition we follow Fabes and Riviere [FR1] and define a half-order time derivative by IDnA(x, t) = ( τ ‖(ξ, τ)‖ Â(ξ, τ) )̌ (x, t) (0.3) whereˆandˇdenote respectively the Fourier and inverse Fourier transforms on IR, and ξ, τ denote, respectively, the space and time variables on the Fourier transform side. Also ‖z‖ denotes the parabolic “ norm ” of z. We recall that this “ norm ” satisfies the non-isotropic dilation invariance property ‖(δx, δt)‖ ≡ δ‖(x, t)‖. Indeed, ‖(x, t)‖ is defined as the unique positive solution ρ of the equation n−1 ∑ i=1 xi ρ2 + t ρ4 = 1. (0.4) The half order smoothness condition in the time variable which we impose upon A is that IDnA ∈ (parabolic) BMO. We recall that parabolic BMO is the space of all locally integrable 2 functions modulo constants satisfying ‖b‖∗ ≡ sup B 1 |B| ∫ B |b(z)−mBb| dz < ∞. (0.5) Here, z = (x, t) and B denotes the parabolic ball B ≡ Br(z0) ≡ {z ∈ IR : ‖z − z0‖ < r} (0.6) where |B| denotes the Lesbegue n measure of B and mBb ≡ 1 |B| ∫ B b(z)dz. We note that |Br(z0)| ≡ cr where c is a constant and d = n + 1 is the homogeneous dimension of IR endowed with the metric induced by ‖ · ‖. We observe that IR so endowed is a space of homogeneous type in the sense of Coifman and Weiss [CW]. Indeed, there is a polar decomposition z ≡ (x, t) ≡ (ρθ1, . . . , ρθn−1, ρθn), dz ≡ dxdt ≡ ρd−1(1 + θ n)dρ dθ (0.7) where θ = (θ1, . . . , θn), |θ| = 1, and dθ denotes surface area on the unit sphere. Throughout this paper Lp(IRn−1), 1 < p < ∞, denotes, as usual, the space of p th power integrable functions f on IRn−1 with norm, ‖f‖p . To explain the significance of the conditions which we have imposed upon A, we recall a result of the first author [H1], which states that ∥∥∥∥∥ ∆− ∂ ∂t , A  ∥∥∥∥∥ op ≈ ‖∇xA‖∞ + ‖IDnA‖∗, where ≈ means the two quantities are bounded by constant multiples of each other. Moreover, ‖ · ‖ denotes the operator norm on L2(IRn−1), and ∇x ≡ ( ∂ ∂x1 , . . . , ∂ ∂xn−1 ). (0.8)

Identification of faces in a 2D line drawing projection of a wireframe object

Abstract: An important key to reconstructing a three-dimensional object depicted by a two-dimensional line drawing projection is face identification. Identification of edge circuits in a 2D projection corresponding to actual faces of a 3D object becomes complex when the projected object is in wireframe representation. This representation is commonly encountered in drawings made during the conceptual design stage of mechanical parts. When nonmanifold objects are considered, the situation becomes even more complex. This paper discusses the principles underlying face identification and presents an algorithm capable of performing this identification. Face-edge-vertex relationships applicable to nonmanifold objects are also proposed. Examples from a working implementation are given.

A Structure Preserving Encoding of Z in Isabelle/HOL

Abstract: We present a semantic representation of the core concepts of the specification language Z in higher-order logic. Although it is a “shallow embedding” like the one presented by Bowen and Gordon, our representation preserves the structure of a Z specification and avoids expanding Z schemas. The representation is implemented in the higher-order logic instance of the generic theorem prover Isabelle. Its parser can convert the concrete syntax of Z schemas into their semantic representation and thus spare users from having to deal with the representation explicitly. Our representation essentially conforms with the latest draft of the Z standard and may give both a clearer understanding of Z schemas and inspire the development of proof calculi for Z.

A Concept Language Extended with Different Kinds of Transitive Roles

Abstract: Motivated by applications that demand for the adequate representation of part-whole relations, different possibilities of representing transitive relations in terminological knowledge representation systems axe investigated. A well-known concept language, ALC, is extended by three different kinds of transitive roles. It turns out that these extensions differ largely in expressiveness and computational complexity, hence this investigation gives insight into the diverse alternatives for the representation of transitive relations such as part-whole relations, family relations or partial orders in general.

Shared understanding in computer-supported collaborative design

Abstract: We propose that computer-support for collaborative design requires a shared understanding of the design artifact among a design team. The development and support for this shared understanding builds on current developments and research in AI, cad , CSCW and computational models of design. The shared understanding should be an explicit representation in order to be effectively shared. The explicit representation should comprise both a visual representation and a semantic model. In this paper we present an architecture for computer-supported collaborative design that distinguishes between a shared visual representation and a shared underlying representation. The development of the underlying representation combines graphical and semantic objects than can be abstracted and aggregated as a tangled hierarchy.

Computational system and method for modeling the heart

Abstract: A computational model for simulating and predicting the electrical and chemical dynamics of the heart. The model consists of a computerized representation of heart anatomy and a system of mathematical equations that describe the spatio-temporal behavior of biophysical quantities such as voltage at various locations throughout the heart. The computer process can present the temporal evolution of the biophysical quantities throughout the computerized anatomical model.

Orientation-Free Representations from Navigation through a Computer-Simulated Environment:

Abstract: Navigating through an environment and viewing a map of that environment can result in different types of cognitive representation. Maps are typically encoded in the same onentation that they are vi...

The representation of agents: anthropomorphism, agency, and intelligence

Abstract: Agents have become a predominant area of research and development in human interfaces. A major issue in the development of these agents is how to represent them and their activities to the user. Anthropomorphic forms have been suggested, since they provide a great degreeof subtlety and afford social interaction. However, these forms may be problematic since they maybe inherently interpretted as having a high degreeof agency and intelligence. An experiment is presented which supports these contentions.

Kings of Stone: A Consideration of Stelae in Ancient Maya Ritual and Representation

Abstract: vague year\" in numerous other types of temporal statements, including distance numbers. This sign never, however, overlaps with TUN; their distribution is mutually exclusive. Stuart: Kings of stone 151 Figure 2. The tun, \"stone\" glyph and its uses in so-called \"year counts.\" (a) The common spelling TUN-ni for tun. (b) CHUM-TUN-ni for chumtun, \"stone seating.\" (c) 13-TUN-ni for 13 tun, \"thirteen stones.\" Drawings: David Stuart. 1954). Curiously, the sites of Palenque and Pomona, which feature the numbered tun counts described above, were not in the custom of erecting stelae or large outdoor altars. Clearly some other type of \"stone\" must be alluded to, perhaps even smaller types of ritual stones such as jade beads or pebbles (reminiscent of the small stones are used by modern day-keepers and diviners) although this would be impossible to verify. For the time being, however, we can see that many of the same fan-centered ceremonies attested in the conquest era have clear precedence in early Maya ritual behavior as expressed in hieroglyphic texts. Moreover, we can conclude with some degree of certainty that some abstract concepts of time-keeping and the terminology surrounding those concepts were directly connected in important ways with material stone objects, or tuns. Dedicated tuns, whatever form they took, served in some capacity as representations?one might even say \"embodiments\"?of time itself. Deciphering the ancient term for \"stela\" Among the significant discoveries in the last decade of Maya epigraphic studies is the realization that a great many texts possess a strong self-referential quality. That is to say, texts that grace large public monuments and even everyday portable objects such as pottery vessels tend to simply record facts about the object in question: the dedication date of a stela, the name of the \"owner\" of a drinking vessel, and the types of ritual that are used to ceremonially \"activate\" these important objects. I would go so far as to say that sacred or important objects are the principal concern of most of the extant Maya texts, rather than the deeds and histories of royal figures.2 Many of the texts that do record elite history, in fact, concern the ritual interaction between rulers and objects, stelae constituting a significant sub-group of the latter. Some stelae were even given their own personal names and might themselves be considered \"participants\" in ancient Maya ritual and historical narrative. This model of Maya textual practice has emerged over the last decade and a half through a series of related decipherments. In 1979, Peter Mathews deciphered the signs U-tu-pa inscribed upon a jadeite earspool as u-tup, \"his earspool\" (Mathews 1979; see also Justeson 1983). With this advance in mind, I posited in 1982 the reading U-ba-ki, or u-bak, \"his bone,\" for a glyph found on a set of inscribed bone artifacts excavated at Tikal.3 Stephen Houston and Karl Taube (1987) soon recognized U-la-ka, or u-lak, \"his dish,\" inscribed on several ceramic plates. It quickly became apparent that various portable media with glyphic texts were commonly inscribed with such name tags, and thus the process of identifying the hieroglyphs for other owned items became a straightforward matter. It was soon found that certain hieroglyphs marked with the pronoun \"his, her, or its\" consistently appeared on specific types of objects or monuments with personal names of individuals (Houston et al. 1989). It comes as little surprise, therefore, that hieroglyphs incorporating the word tun function in much the same way on stone objects. An unpublished carved jade from Tikal, excavated by the University of Pennsylvania, bears an inscription introduced by the phrase U TUN-ni, for u-tun, \"her stone,\" followed by a woman's name. Often the same TUN element takes on certain 2. The interpretation of inscribed texts as little more than royal propaganda is recently argued by Marcus (1992). The frequent textual emphasis on things rather than people is discussed in more detail in Stuart (1995). 3. A decipherment circulated among colleagues in an unpublished 1983 paper entitled \"Hieroglyphic Name Tags on the Tikal Bones.\" 152 RES 29/30 SPRING/AUTUMN 1996 modifying signs that specify the type of stone labeled, allowing us to classify Maya monuments according to a native typology, much like what has been done with ceramics (Houston et al. 1989). At the Maya site of Copan, for instance, an unusual set of monumental stone vessels with lids is labeled with the glyph reading saklaktun, which might be translated as \"artificial dish stone\" (fig. 3). These objects served as skeuomorphic versions of ceramic dishes used for the burning of incense (lak) and were thus considered \"artificial\" in a sense. The inscriptions on these stone censers usually include the name of the royal owner (although this could be omitted as it was understood to be the king) and a dedication verb referring to some act performed upon the saklaktun. This principal element verbal hieroglyph represents the head of a doglike animal embellished by certain distinctive characteristics (Macleod 1989). Precisely the same verb occurs in the dedicatory texts of many other inscriptions and on other types of stone monuments. Its reading is difficult to establish with much assurance, but one possible reading is wa', meaning \"stand up,\" recalling one of the attested meanings we have seen for the dedicatory term ts'ap. Taken together, the inscriptions on the Copan censers would read \"On [a given date] his stone censer stood-up.\" A specialized term for \"stela,\" also based upon tun, can be identified with some ease by its appearance in parallel dedicatory texts on stelae. Such dedicatory statements are very common and are widely distributed among Maya sites. For example, inscribed on Monument 30 from the site of Tonina is a typical example of a stela dedication record that is structurally identical to the phrase described above (fig. 4). A date introduces the inscription (details are illegible, unfortunately) and the verb is again the possible wa' glyph used for the saklaktun censers at Copan (fig. 4). A possessed noun comes next, which, as we might expect, is based on the word fun; there is a plantlike sign in front of tun that appears to be a modifying element. The individual who \"possesses\" this stone is named in the last glyph, a name that remains phonetically undeciphered, though Mathews (1982) has identified it as a Tonina ruler.4 The inscription therefore reads: \"(Date), it is stood-up, it is his (plantlike modifier) Figure 3. Inscription on lid of stone incense burner (CPN 270). Copan, Honduras. Drawing: David Stuart. Figure 4. Inscription on the back of Monument 30. Tonina, Mexico. From Graham and Mathews 1996:77. Drawing: Peter Mathews. 4. This ruler is called Ruler 5 in the dynastic sequence proposed by Peter Mathews (1982). A recently unearthed inscription at Tonina, illustrated in Yadeun (1993:132), also names him as a royal protagonist. Stuart: Kings of stone 153 stone, (ruler's name).\" The inscription contains the familiar name-tag structure, allowing us to infer that, since it appears on a stela, the possessed noun based upon \"stone\" is the glyph for \"stela.\" We can reasonably suggest such a meaning for the glyph without yet knowing its precise phonetic reading. The missing component is the phonetic value of the plantlike sign before tun. The hypothesis that the \"plant stone\" glyph (fig. 5) (a label of convenience and not a translation) stands for \"stela\" is supported by its frequent appearance on stelae throughout Maya inscriptions. Indeed, it is nearly exclusively found on stelae where it would seem to tag these monuments in much the same manner as we find simple labels of ownership on smaller ritual objects. It should be noted that the glyph in question assumes various forms determined by regional style and by the propensities of the Maya writing system to manipulate the constituent elements of a glyph block by visually conflating them. Thus we sometimes encounter the \"plant\" and \"stone\" signs fused into what looks to be a single sign. This may simply be a means of conserving text space, but the frequency of the combined signs suggests that it has an almost logographic function, as if it were a single sign for \"stela.\" For example, in the inscription of El Peru Stela 35, recorded during explorations of that site by Ian Graham, we find that the \"stela\" glyph is conflated, but the constituent signs remain easily discernible (fig. 6). Here it takes the possessive upronoun and suffix -//, marking it as a possessed noun. The name of the stela's owner follows in the next glyphs as we saw on Tonina Monument 30. Does a clue to the decipherment of the plantlike modifier on tun lie in the appearance of the sign itself? Or, put plainly, could the word represented by this sign have something to do with plants or trees? A leaflike element is readily seen at the upper right of the sign, at the end of a bent \"stemlike\" device. When the study of this sign began in earnest in the late 1980s, Linda Schele and I posited that the reading of the stela glyph was perhaps TE'-TUN, or \"tree stone\"?an appropriate description, it seemed, for a freestanding and upright stone column (Schele and Stuart 1986). This reading has filtered into much Mayanist literature (e.g., Schele and Friedel 1990:71). However, on the basis of new epigraphic evidence, I am now in the position to reject this earlier interpretation. As we now know, the pictorial qualities of a hieroglyphic sign are seldom a firm basis upon which to propose a new reading. Not only is the image sometimes difficult to recognize, but without phonetic clues we would have little basis for establishing the Maya word represented by the image. A \"tree\" might be used to represent several different concepts. With this said, it is now possible to move forward toward a decipherment by looking at its varied contexts and at possible phonetic c

On the Representation of Context

Abstract: This paper revisits some foundational questions concerning the abstract representation of a discourse context. The context of a conversation is represented by a body of information that is presumed to be shared by the participants in the conversation – the information that the speaker presupposes a point at which a speech act is interpreted. This notion is designed to represent both the information on which context-dependent speech acts depend, and the situation that speech acts are designed to affect, and so to be a representation of context that is appropriate for explaining the interaction of context and the contents expressed in them. After reviewing the motivating ideas and the outlines of the apparatus, the paper responds to a criticism of the framework, and considers the way it can help to clarify some phenomena concerning pronouns with indefinite antecedents.

Computer models for representation of digital-based excitation systems. Commentary

Abstract: Computer Models suitable for representation of newer digital-based excitation systems in transient stability programs are presented in this paper. These models are an addendum to the most recent issued IEEE standard 421.5 (1992) for recommended excitation system models. It is the intent of the subcommittee to include these models in standard 421.5 at the time of its next revision.