Interval Type-2 Fuzzy Logic Systems Made Simple

To date, because of the computational complexity of using a general type-2 fuzzy set (T2 FS) in a T2 fuzzy logic system (FLS), most people only use an interval T2 FS, the result being an interval T2 FLS (IT2 FLS). Unfortunately, there is a heavy educational burden even to using an IT2 FLS. This burden has to do with first having to learn general T2 FS mathematics, and then specializing it to an IT2 FSs. In retrospect, we believe that requiring a person to use T2 FS mathematics represents a barrier to the use of an IT2 FLS. In this paper, we demonstrate that it is unnecessary to take the route from general T2 FS to IT2 FS, and that all of the results that are needed to implement an IT2 FLS can be obtained using T1 FS mathematics. As such, this paper is a novel tutorial that makes an IT2 FLS much more accessible to all readers of this journal. We can now develop an IT2 FLS in a much more straightforward way     

Secure Agents

With the rapid proliferation of software agents, there comes an increased need for agents to ensure that they do not provide data and/or services to unauthorized users. We first develop an abstract definition of what it means for an agent to preserve data/action security. Most often, this requires an agent to have knowledge that is impossible to acquire – hence, we then develop approximate security checks that take into account, the fact that an agent usually has incomplete/approximate beliefs about other agents. We develop two types of security checks – static ones that can be checked prior to deploying the agent, and dynamic ones that are executed at run time. We prove that a number of these problems are undecidable, but under certain conditions, they are decidable and (our definition of) security can be guaranteed. Finally, we propose a language within which the developer of an agent can specify her security needs, and present provably correct algorithms for static/dynamic security verification.     

Stabilization via homogeneous feedback controls

In this paper, we provide an explicit homogeneous feedback control with the requirement that a control Lyapunov function exists for an affine control system and satisfies an homogeneous condition. We use a modified version of the Sontag formula to achieve our main goal. Moreover, we prove that the existence of an homogeneous control Lyapunov function for an homogeneous affine system leads to an homogeneous closed-loop system by using the previous feedback control.     

Application of SQL/N to the attribute-relation associations implicit in functional dependencies

SQL/N is an expressive nonprocedural data base language that is upward compatible with SQL. Its expressive power is derived from both the use of natural quantifiers and the quantification of subsets of relations, in particular the subsets that are the groups of related tuples that occur in associations between relations. We show that SQL/N is also very expressive in specifying requests involving attribute-relation associations, and that attribute-relation associations are implicit in functional dependencies. We show that an attribute-relation association may be derived from the association between an algebraic projection relation and the relation on which the projection operation is performed. Two common cases of attribute-relation associations are investigated: first the case of an association restricted to a single relation, and second a more general attribute-relation association where an attribute from one relation is associated with a second relation.     

An adaptive mixed finite element method for wind field adjustment

In this paper we present an adaptive strategy to obtain an incompressible wind field that adjusts to an experimental one, and verify boundary conditions of physical interest. We use an augmented lagrangian formulation for solving this problem. Our method is based on an Uzawa iteration to update the lagrange multiplier and on an elliptic adaptive inner iteration for velocity. Several examples show that the proposed method is efficient and reliable.     

Exploratory research on reading cognition and escape-route planning using building evacuation plan diagrams

The purpose of evacuation plan diagrams is for readers to comprehend and then plan an evacuation route. However, comprehending such diagrams involves complex issues that have yet to be addressed by research. This study aims to investigate how Taiwanese people interpret evacuation plan diagrams in their buildings. Issues of interest include the amount of time that it takes for a member of the general public to read a diagram and the time that they spend planning their escape route. Correlated and influencing factors are analyzed. The floor plan of an actual department store was used as the diagram for cognitive testing. A method of stimulated measurement was conducted over the Internet. The results of the experiment showed that the time it takes to plan an escape route is about 1.1 to 2 times longer than its reading time. This indicates that there is a significant time difference between diagram interpretation and stimulated planning. It was found that the longer it takes to read a diagram, the longer it takes to plan an escape route. In addition, to understand the difference between interpretations by the general public versus those with an architectural background, an analysis showed that the general public takes two to three times longer than architectural professionals to read a diagram and plan an escape route. Consequently, improvements in reading diagrams could help in the planning of a more efficient escape route. Furthermore, through our analysis, we found that the design of diagram symbols must satisfy conventional use and also that diagrams must avoid the use of metaphorical and abstract symbols. Diagrams that follow our guidelines will generally result in more effective and efficient conveyance of the intended message, thereby assisting in an emergency.     

INFORMATION INFRASTRUCTURE MANAGEMENT

Corporate survival in an information economy requires that IS managers assume the new role of information infrastructure management, an architecture-focused approach that results in an integrated IS and business organization with an integrated strategic plan. The approach enables IS managers to anticipate future organizational demands and stimulate innovative redesign of business processes to continuously improve performance.     

EVENT TRACKING IN A DYNAMIC MULTIAGENT ENVIRONMENT

In a dynamic, multiagent environment, an automated intelligent agent is often faced with the possibility that other agents may instigate events that hinder or help the achievement of its own goals. To act intelligently in such an environment, an automated agent needs an event tracking capability to continually monitor the occurrence of such events and the temporal relationships among them. This capability enables an agent to infer the occurrence of important unobserved events as well as to obtain a better understanding of the interaction among events. This article focuses on event tracking in one complex and dynamic multiagent environment: the air-combat simulation environment. It analyzes the challenges that an automated pilot agent must face when tracking events in this environment. This analysis reveals three new issues that have not been addressed in previous work in this area: (i) tracking events generated by agents' flexible and reactive behaviors, (ii) tracking events in the context of continuous agent interactions, and (iii) tracking events in real time. This article proposes one solution to address these issues. One key idea in this solution is that the (architectural) mechanisms that an agent employs in generating its own flexible and reactive behaviors can be used to track other agents' flexible and reactive behaviors in real time. A second key idea is the use of a world-centered representation for modeling agent interactions. The solution is demonstrated using an implementation of an automated pilot agent.     

All-in-focus imaging using average filter-based relative focus measure

Digital images are normally taken by focusing on an object, resulting in defocused background regions. A popular approach to produce an all-in-focus image without defocused regions is to capture several input images at varying focus settings, and then fuse them into an image using offline image processing software. This paper describes an all-in-focus imaging method that can operate on digital cameras. The proposed method consists of an automatic focus-bracketing algorithm that determines at which focuses to capture images and an image-fusion algorithm that computes a high-quality all-in-focus image. While most previous methods use the focus measure calculated independently for each input image, the proposed method calculates the relative focus measure between a pair of input images. We note that a well-focused region in an image shows better contrast, sharpness, and details than the corresponding region that is defocused in another image. Based on the observation that the average filtered version of a well-focused region in an image shows a higher correlation to the corresponding defocused region in another image than the original well-focused version, a new focus measure is proposed. Experimental results of various sample image sequences show the superiority of the proposed measure in terms of both objective and subjective evaluation and the proposed method allows the user to capture all-in-focus images directly on their digital camera without using offline image processing software.     

Efficient inclusion testing for simple classes of unambiguous ω-automata

We show that language inclusion for languages of infinite words defined by nondeterministic automata can be tested in polynomial time if the automata are unambiguous and have simple acceptance conditions, namely safety or reachability conditions. An automaton with safety condition accepts an infinite word if there is a run that never visits a forbidden state, and an automaton with reachability condition accepts an infinite word if there is a run that visits an accepting state at least once.     

On two-way weak counter machines

In this paper we consider two-way counter machines, i.e., two-way finite automata with counters whose contents have no effect on transitions except that an attempt to decrement an empty counter will abort the computation. We show that the deterministic machines have an unsolvable emptiness problem, but that their universe problem is solvable because they accept languages whose complements are context free. In the nondeterministic case, we show that these machines are equivalent to two-way nondeterministic logspace Turing machines, and establish an infinite hierarchy based on the number of weak counters. Finally, we disprove two conjectures concerning the nondeterministic machines.     

An exact algorithm for parallel machine scheduling with conflicts

We consider an extension of classic parallel machine scheduling where a set of jobs is scheduled on identical parallel machines and an undirected conflict graph is part of the input. Each node in the graph represents a job, and an edge implies that its two jobs are conflicting, meaning that they cannot be scheduled on the same machine. The goal is to find an assignment of the jobs to the machines such that the maximum completion time (makespan) is minimized. We present an exact algorithm based on branch and price that combines methods from bin packing, scheduling, and graph coloring, with appropriate modifications. The algorithm has a good computational performance even for parallel machine scheduling without conflicting jobs.     

A generalization of Thue freeness for partial words

This paper approaches the combinatorial problem of Thue freeness for partial words. Partial words are sequences over a finite alphabet that may contain a number of “holes”. First, we give an infinite word over a three-letter alphabet which avoids squares of length greater than two even after we replace an infinite number of positions with holes. Then, we give an infinite word over an eight-letter alphabet that avoids longer squares even after an arbitrary selection of its positions are replaced with holes, and show that the alphabet size is optimal. We find similar results for overlap-free partial words.     

Analysis of AIMD protocols over paths with variable delay

The throughput of AIMD protocols in general and of TCP in particular, has been computed in many existing works by modeling the round-trip time as a constant and thus replacing it by its expectation. There are however many scenarios in which the delays of packets vary, causing a variation of the round-trip time. Many typical scenarios occur in wireless and mobile networks. We propose in this paper an analytical model that accounts for the variability of delay, while computing the throughput of an AIMD protocol. We derive a closed-form expression for the throughput, that illustrates the impact of delay variability. We show by analysis and simulation, that an increase in the variability of delay improves the performance of an AIMD protocol. Thus, an analytical model that only considers the average delay could underestimate the performance of an AIMD protocol in scenarios where delay is variable.     

The alternator

An alternator is an array of interacting processes that satisfy three conditions. First, if a process has an enabled action at some state, then no neighbor of that process has an enabled action at the same state. Second, along any concurrent execution, each action is executed infinitely often. Third, along any maximally concurrent execution, the alternator is stabilizing to states where the number of enabled actions is maximal. In this paper, we specify an alternator with arbitrary topology and verify its correctness. We also show that this alternator can be used in transforming any system that is stabilizing assuming serial execution, to one that is stabilizing assuming concurrent execution.     

Context-aware Volume Modeling of Skeletal Muscles

This paper presents an interactive volume modeling method that constructs skeletal muscles from an existing volumetric dataset. Our approach provides users with an intuitive modeling interface and produces compelling results that conform to the characteristic anatomy in the input volume. The algorithmic core of our method is an intuitive anatomy classification approach, suited to accommodate spatial constraints on the muscle volume. The presented work is useful in illustrative visualization, volumetric information fusion and volume illustration that involve muscle modeling, where the spatial context should be faithfully preserved.     

Classifying matrices separating rows and columns

The classification problem transforms a set of N numbers in such a way that none of the first N/2 numbers exceeds any of the last N/2 numbers. A comparator network that solves the classification problem on a set of r numbers is commonly called an r-classifier. We show how the well-known Leighton's Columnsort algorithm can be modified to solve the classification problem of N=rs numbers, with 1 /spl les/ s /spl les/ r, using an r-classifier instead of an r-sorting network. Overall, the r-classifier is used O(s) times, namely, the same number of times that Columnsort applies an r-sorter. A hardware implementation is proposed that runs in optimal O(s+logr) time and uses an O(rlogr(s + logr)) work. The implementation shows that, when N= rlogr, there is a classifier network solving the classification problem on N numbers in the same O(logr) time and using the same O(rlogr) comparators as an r-classifier, thus saying a logr factor in the number of comparators over an (rlogr)-classifier.     

Optimal sensor selection for discrete-event systems with partial observation

For discrete-event systems under partial observation, we study the problem of selection of an optimal set of sensors that can provide sufficient yet minimal events observation information. The sufficiency of the observed information is captured as the fulfillment of a desired formal property. Selection of sensors can be viewed as a selection of an observation mask and also of an equivalence class of events. A sensor set is called optimal if any coarser selection of the corresponding equivalence class of events results in some significant loss of the events observation information. We study an optimal selection of sensors over the set of general "nonprojection" observation masks. We show that this problem is NP hard in general. For mask-monotonic properties, we present a "top-down" and a "bottom-up" algorithm each of polynomial complexity. We show that observerness is not mask-monotonic. We show that the computational complexity can be further improved if the property is preserved under the projection via an intermediary observation mask that is an observer. Our results are obtained in a general setting so that they can be adapted for an optimal selection of sensors for a variety of applications.     

Characterizing and recognizing the visibility graph of a funnel-shaped polygon

A funnel, which is notable for its fundamental role in visibility algorithms, is defined as a polygon that has exactly three convex vertices, two of which are connected by a boundary edge. In this paper we investigate the visibility graph of a funnel which we call an F-graph.We first present two characterizations of an F-graph, one of whose sufficiency proof itself is a linear time Real RAM algorithm for drawing a funnel on the plane that corresponds to an F-graph. We next give a linear-time algorithm for recognizing an F-graph. When the algorithm recognizes an F-graph, it also reports one of the Hamiltonian cycles defining the boundary of its corresponding funnel. This recognition algorithm takes linear time even on a RAM.We finally show that an F-graph is weakly triangulated and therefore perfect, which agrees with the fact that perfect graphs are related to geometric structures.This work was supported in part by the Korea Science and Engineering Foundation under Grant 91-01-01.     

人工系统中数据–因素–算力–算法作用及相互关系研究

目前的研究认为人工智能的核心是数据、算法和算力,但因素在形成人工智能系统过程中是必不可少的。论文针对人工系统中的数据、算力、算法和因素的各自作用,及其相互关系进行了探讨和论证。从人工系统的内涵出发,描述人工系统的发展过程,认为目前和今后的人工系统必将具有人工智能特征,而实现人工系统要充分考虑上述四方面的相互作用。研究结果表明:数据是人工系统辨识因素的基础,也是形成算法的基础;因素是人工系统控制自然系统的方法及算法所需变量;算法体现了因素与数据关系,可描述人工系统结构;算力是解算算法的能力,也需考虑数据和因素的特征。因此因素在人工系统建立过程中与数据、算法和算力具有相同的重要性。它们具有明显的作用关系,且普遍存在于各个学科,是形成各学科理论基础体系的关键。