Gradual elements in a fuzzy set

The notion of a fuzzy set stems from considering sets where, in the words of Zadeh, the “transition from non-membership to membership is gradual rather than abrupt”. This paper introduces a new concept in fuzzy set theory, that of a gradual element. It embodies the idea of fuzziness only, thus contributing to the distinction between fuzziness and imprecision. A gradual element is to an element of a set what a fuzzy set is to a set. A gradual element is as precise as an element, but the former is flexible while the latter is fixed. The gradual nature of an element may express the idea that the choice of this element depends on a parameter expressing some relevance or describing some concept. Applications of this notion to fuzzy cardinality, fuzzy interval analysis, fuzzy optimization, and defuzzification principles are outlined.     

Tree automata with equality constraints modulo equational theories

This paper presents new classes of tree automata combining automata with equality test and automata modulo equational theories. We believe that these classes have a good potential for application in e.g. software verification. These tree automata are obtained by extending the standard Horn clause representations with equational conditions and rewrite systems. We show in particular that a generalized membership problem (extending the emptiness problem) is decidable by proving that the saturation of tree automata presentations with suitable paramodulation strategies terminates. Alternatively our results can be viewed as new decidable classes of first-order formula.     

Mass spectrometry in nutrition: understanding dietary health effects at the molecular level

In modern nutrition research, mass spectrometry has developed into a tool to assess health, sensory as well as quality and safety aspects of food. In this review, we focus on health-related benefits of food components and, accordingly, on biomarkers of exposure (bioavailability) and bioefficacy. Current nutrition research focuses on unraveling the link between dietary patterns, individual foods or food constituents and the physiological effects at cellular, tissue and whole body level after acute and chronic uptake. The bioavailability of bioactive food constituents as well as dose-effect correlations are key information to understand the impact of food on defined health outcomes. Both strongly depend on appropriate analytical tools to identify and quantify minute amounts of individual compounds in highly complex matrices--food or biological fluids--and to monitor molecular changes in the body in a highly specific and sensitive manner. Based on these requirements, mass spectrometry has become the analytical method of choice with broad applications throughout all areas of nutrition research. The current review focuses on selected areas of application: protein and peptide as well as nutrient and metabolite analysis.     

Inverse display characterization: A two‐step parametric model for digital displays

Abstract— A simple additivity model is often used as a basic model for digital‐display characterization. However, such a simple model cannot satisfy the needs of demanding color‐management applications all the time. On the other hand, systematic sampling of the color space and 3‐D interpolation is an expensive method in terms of measurement and computation time when precision is needed. This paper presents an enhanced method to characterize the XYZ‐to‐RGB transform of a digital display. This parametric method exploits the independence between the luminance variation of the electro‐optic response and the colorimetric responses for certain display types. The model is generally applicable to digital displays, including 3‐DMD projectors, single DMDs, CRTs, LCDs, etc., if the independence condition is satisfied. While the problem to solve is a 3‐D‐to‐3‐D transformation (from XYZ to RGB), the proposed parametric model is the composition of a 2‐D transform followed by a 1‐D transform. The 2‐D transform manages the chromatic aspects and, in succession, the 1‐D transform manages the luminance variations. This parametric digital model is applicable in the field of color management, with the objective of characterizing digital displays and applying a reference look such as a film look.     

Bargaining on an Internet Agent-based Market: Behavioral vs. Optimizing Agents

In this paper, we analyze an Internet agent-based market where non-cooperative agents using behavioral rules negotiate the price of a given product in a bilateral and sequential manner. In this setting, we study the optimal decision-making process of a buying agent that enters the market. Our approach is based on Negotiation Analysis (Raiffa, 1982; Sebenuis, 1992) and we consider that the optimizing buying agent maximizes her discounted expected utility using subjective probabilities. The optimal decision-making process of the buying agent is treated as a stochastic control problem that can be solved by dynamic programming. Three types of behavioral agents are studied, namely conceder agents, boulware agents and imitative agents. A set of simulations is undertaken in order to predict the average outcome in a negotiation process for different parameters of the optimizing buying agent and for the three possible selling agents' behaviors. Finally, we compare the performance of the optimizing agent with that of behavioral buying agents.     

Realistic haptic rendering of interacting deformable objects in virtual environments

A new computer haptics algorithm to be used in general interactive manipulations of deformable virtual objects is presented. In multimodal interactive simulations, haptic feedback computation often comes from contact forces. Subsequently, the fidelity of haptic rendering depends significantly on contact space modeling. Contact and friction laws between deformable models are often simplified in up to date methods. They do not allow a "realistic" rendering of the subtleties of contact space physical phenomena (such as slip and stick effects due to friction or mechanical coupling between contacts). In this paper, we use Signorini's contact law and Coulomb's friction law as a computer haptics basis. Real-time performance is made possible thanks to a linearization of the behavior in the contact space, formulated as the so-called Delassus operator, and iteratively solved by a Gauss-Seidel type algorithm. Dynamic deformation uses corotational global formulation to obtain the Delassus operator in which the mass and stiffness ratio are dissociated from the simulation time step. This last point is crucial to keep stable haptic feedback. This global approach has been packaged, implemented, and tested. Stable and realistic 6D haptic feedback is demonstrated through a clipping task experiment.     

A systematic approach to the assessment of fuzzy association rules

In order to allow for the analysis of data sets including numerical attributes, several generalizations of association rule mining based on fuzzy sets have been proposed in the literature. While the formal specification of fuzzy associations is more or less straightforward, the assessment of such rules by means of appropriate quality measures is less obvious. Particularly, it assumes an understanding of the semantic meaning of a fuzzy rule. This aspect has been ignored by most existing proposals, which must therefore be considered as ad-hoc to some extent. In this paper, we develop a systematic approach to the assessment of fuzzy association rules. To this end, we proceed from the idea of partitioning the data stored in a database into examples of a given rule, counterexamples, and irrelevant data. Evaluation measures are then derived from the cardinalities of the corresponding subsets. The problem of finding a proper partition has a rather obvious solution for standard association rules but becomes less trivial in the fuzzy case. Our results not only provide a sound justification for commonly used measures but also suggest a means for constructing meaningful alternatives.

Virtual Reality Interfaces for Visualization and Control of Remote Vehicles

The Autonomy and Robotics Area (ARA) at NASA Ames Research Center has investigated the use of various types of Virtual Reality-based operator interfaces to remotely control complex robotic mechanisms. In this paper, we describe the major accomplishments and technology applications of the ARA in this area, and highlight the advantages and issues related to this technology.