Showing papers on "Fuzzy logic published in 1977"
TL;DR: In this article, a fuzzy logic is used to synthesize linguistic control protocol of a skilled operator for industrial plants, which has been applied to pilot scale plants as well as in practical situations.
Abstract: This paper describes an application of fuzzy logic in designing controllers for industrial plants. A fuzzy logic is used to synthesize linguistic control protocol of a skilled operator. The method has been applied to pilot scale plants as well as in practical situations. The merits of this method and its usefulness to control engineering are discussed. An avenue for further work in this area is described where the need is to go beyond a purely descriptive approach, and means for implementing a prescriptive or a self-organizing system are explored.
2,011 citations
TL;DR: The fuzzy control algorithm is used to implement linguistically expressed heuristic control policies directly, with a view to automating those complex and poorly-defined processes where modelling difficulties and lack of suitable measurements make manual control imperative.
740 citations
01 Jul 1977-International Journal of Human-computer Studies \/ International Journal of Man-machine Studies
TL;DR: This paper presents a model for solving multi-objective decision problems when the objectives are of varying degrees of importance by assigning to each objective a power indicative of its importance and then raising each fuzzy set to its appropriate power.
Abstract: One of the most useful aspects of fuzzy set theory is its ability to represent multio-bjective decision problems involving vague or fuzzy objectives. This paper presents a model for solving multi-objective decision problems when the objectives are of varying degrees of importance. This is done by assigning to each objective a power indicative of its importance and then raising each fuzzy set to its appropriate power. These powers are obtained by getting the eigenvector of the maximum eigenvalue of a matrix of paired comparisons of the objectives.
452 citations
01 Oct 1977
TL;DR: It is shown that the use of a fuzzy logic controller results in a better performance than a conventional effective vehicle-actuated controller.
Abstract: Work done on the implementation of a fuzzy logic controller in a single intersection of two one-way streets is presented. The model of the intersection is described and validated, and the use of the theory of fuzzy sets in constructing a controller based on linguistic control instructions is introduced. The results obtained from the implementation of the fuzzy logic controller are tabulated against those corresponding to a conventional effective vehicle-actuated controller. With the performance criterion being the average delay of vehicles, it is shown that the use of a fuzzy logic controller results in a better performance.
380 citations
TL;DR: In this paper, some sufficient conditions for convergence under “max(min)” products of the powers of a square fuzzy matrix and of a fuzzy state process are established.
229 citations
TL;DR: Techniques for processing simple fuzzy queries expressed in the relational query language SEQUEL are introduced and the feasibility of implementing such techniques in a real environment is studied.
Abstract: This paper is concerned with techniques for fuzzy query processing in a database system. By a fuzzy query we mean a query which uses imprecise or fuzzy predicates (e.g. AGE = “VERY YOUNG”, SALARY = “MORE OR LESS HIGH”, YEAR-OF-EMPLOYMENT = “RECENT”, SALARY ⪢ 20,000, etc.). As a basis for fuzzy query processing, a fuzzy retrieval system based on the theory of fuzzy sets and linguistic variables is introduced. In our system model, the first step in processing fuzzy queries consists of assigning meaning to fuzzy terms (linguistic values), of a term-set, used for the formulation of a query. The meaning of a fuzzy term is defined as a fuzzy set in a universe of discourse which contains the numerical values of a domain of a relation in the system database. The fuzzy retrieval system developed is a high level model for the techniques which may be used in a database system. The feasibility of implementing such techniques in a real environment is studied. Specifically, within this context, techniques for processing simple fuzzy queries expressed in the relational query language SEQUEL are introduced.
189 citations
TL;DR: The notions of initial and final fuzzy topologies are introduced and it is shown that from a categorical point of view they are the right concepts to generalize the topological ones.
158 citations
01 Jan 1977-International Journal of Human-computer Studies \/ International Journal of Man-machine Studies
TL;DR: The main part of the paper consists of a bibliography of some 1150 items, each keyword-indexed with some 750 being classified as concerned with fuzzy system theory and its applications.
Abstract: The main part of the paper consists of a bibliography of some 1150 items, each keyword-indexed with some 750 being classified as concerned with fuzzy system theory and its applications. The remaining items are concerned with closely related topics in many-valued logic, linguistics, the philosophy of vagueness, etc. These background references are annotated in an initial section that outlines the relationship of fuzzy system theory to other developments and provides pointers to various possible fruitful interrelationships. Topics covered include: the philosophy and logic of imprecision and vagueness; other non-standard logics; foundations of set theory; probability theory; fuzzification of mathematical systems; linguistics and psychology; and applications.
152 citations
01 Feb 1977
TL;DR: The fuzzy ISODATA algorithms are used to address two problems: first, the question of feature selection for binary valued data sets is investigated; and second, the same method is applied to the design of a fuzzy one-nearest prototype classifier.
Abstract: The fuzzy ISODATA algorithms are used to address two problems: first, the question of feature selection for binary valued data sets is investigated; and second, the same method is applied to the design of a fuzzy one-nearest prototype classifier The efficiency of this fuzzy classifier is compared to conventional k-NN classifiers by a computational example using the stomach disease data of Scheinok and Rupe, and Toussaint's method for estimation of the probability of misclassification: the fuzzy prototype classifier appears to decrease the error rate expected from all k-NN classifiers by roughly ten per cent
138 citations
TL;DR: Using fuzzy measures and fuzzy integrals, a mathematical model of learning is presented which is able to learn through fuzzy information and is compared with an ordinary Bayesian learning model.
Abstract: Using fuzzy measures and fuzzy integrals, the paper presents a mathematical model of learning which is able to learn through fuzzy information. The characteristics of the model are studied theoretically and in numerical examples, where the model is compared with an ordinary Bayesian learning model. The problem of seeking an extremum of multimodel objective function is given as an example.
01 Dec 1977
TL;DR: The use of fuzzy logic is proposed for the method of failure diagnosis under fuzzy environment and the results obtained show that the present method would be applicable as a methodology of the more general diagnosis.
Abstract: The use of fuzzy logic is proposed for the method of failure diagnosis under fuzzy environment. The distinctive points are the description of the relationship between causes and symptoms by a set of fuzzy relational inequalities and the use of the solutions of the inverse problem of these relations. Recently, the method to solve the inverse problem of fuzzy relational equation has been proposed by E. Sanchez et. al,. A new algorithm for the inverse problem is developed With the consideration on the existence condition of the solution. The proposed scheme of diagnosis is illustrated by considering the diagnosis of car troubles. The results obtained from some numerical examples show that the present method would be applicable as a methodology of the more general diagnosis.
TL;DR: The processing of information about the degree to which items belong to a particular class was investigated in an experiment, and the results strongly supported a simple model which describes the judgment process as directly involving subjective degree-of-truthfulness values.
Abstract: Class membership is a fundamental relationship between concepts in semantic memory. Recent research indicates that, class membership may subjectively be a continuous type of relationship. The processing of information about the degree to which items belong to a particular class was investigated in an experiment in which subjects compared two statements describing class membership relationships. The results strongly supported a simple model which describes the judgment process as directly involving subjective degree-of-truthfulness values. The success of the model indicates that the subjects were able to process this kind of fuzzy information in a consistent and systematic manner. Some of the implications of the human competancy for processing fuzzy information are discussed.
TL;DR: An autopilot for ships designed with the aid of fuzzy sets is investigated, and a comparison is made between the fuzzy and a conventional PID controller which is most commonly used in autopilots.
TL;DR: It is shown, at least for the system of concepts in the social sciences, especially those on a high level of generality, that the theory of psychological tests provides the methodology of construction of measurement tools.
Abstract: The paper explores the possibility of an empirical access to the membership functions of fuzzy sets representing concepts. A formalism is introduced to describe structural features of concepts. It is shown, at least for the system of concepts in the social sciences, especially those on a high level of generality, that the theory of psychological tests provides the methodology of construction of measurement tools.
01 Jan 1977
TL;DR: This paper applies one particular semantical model in a simulation example based on a fuzzy set‐theoretic semantic model of a fragment of the English language, which converts verbal expressions into numerical quantities.
Abstract: This paper introduces and discusses the concept of verbally formulated simulation models. Such models can operate with linguistic values as “high,” “rather high,” “low” and “not low,” etc. as inputs. The output will be similarly verbally formulated. The simulation procedure is based on a fuzzy set‐theoretic semantic model of a fragment of the English language, which converts verbal expressions into numerical quantities. The paper applies one particular semantical model in a simulation example.
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TL;DR: Spectral densities assigning probabilities in each spin state to fuzzy simultaneous values of Sx and Sy are introduced, and their informational completeness is examined.
Abstract: The operational meaning of fuzzy measurement of two spin components Sx and Sy is examined. Spectral densities assigning probabilities in each spin state to fuzzy simultaneous values of Sx and Sy are introduced, and their informational completeness is examined.
Journal Article•
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TL;DR: A graphical scheme (map) for representation and manipulation of fuzzy switching functions is described and properties of the map and relationships between represented implicants are discussed.
Abstract: A graphical scheme (map) for representation and manipulation of fuzzy switching functions is described. Properties of the map and relationships between represented implicants are discussed. Emphasis is placed on illustrations of the use of the map in manipulation and minimization of fuzzy switching functions.
01 Dec 1977
TL;DR: This paper defines and explores the properties of lower and upper inverses of fuzzy relations which extend multi-valued mappings and relates the preceeding notions to possibility distributions in natural languages and to problems of medical diagnosis.
Abstract: In this paper we define and explore the properties of lower and upper inverses of fuzzy relations which extend multi-valued mappings. With the notion of degree of inclusion of non fuzzy sets, we then relate the preceeding notions to possibility distributions in natural languages and to problems of medical diagnosis.
01 Jan 1977
TL;DR: In most decision problems, when the analyst wants to model preferences of one or several decision-makers in a decision process, most of the time distributions have to be considered at a certain stage of the study.
Abstract: In most decision problems, when the analyst wants to model preferences of one or several decision-makers in a decision process, most of the time distributions have to be considered at a certain stage of the study (see Roy, 1975).
01 Dec 1977
TL;DR: In this article, it was shown that the internal model principle is valid for regulators (plant, controller and exosystem) working in fuzzy, environments, and that this principle is also valid for control systems.
Abstract: In the setting of modern algebra, it is shown that the internal model principle is valid for regulators (plant, controller and exosystem) working in fuzzy, environments.
TL;DR: In this article, a survey of the known results concerning infinitely many valued logics is presented, along with some suggestions for alterations of known systems in order to accommodate what modern devotees of fuzzy logic claim to desire.
Abstract: Fuzzy logics are systems of logic with infinitely many truth values. Such logics have been claimed to have an extremely wide range of applications in linguistics, computer technology, psychology, etc. In this note, we canvass the known results concerning infinitely many valued logics; make some suggestions for alterations of the known systems in order to accommodate what modern devotees of fuzzy logic claim to desire; and we prove some theorems to the effect that there can be no fuzzy logic which will do what its advocates want. Finally, we suggest ways to accommodate these desires in finitely many valued logics.
01 Dec 1977
TL;DR: Novel type of synthetic language which is intended t o seme as a t a r g e t l a n g u a g e f o r t h e r e p r e s e n t at i o n of meaning of e x p r E s s i oN s i n a n a t u r a l language.
Abstract: novel type of synthetic language which is intended t o seme as a t a r g e t l a n g u a g e f o r t h e r e p r e s e n t at i o n of meaning of e x p r e s s i o n s i n a n a t u r a l language. PRUF i s based on the premise that the uncer-t a i n t y i n t h e i n t e r p r e t a t i o n o f a p r o p o s i t i o n i n a n a t u r a l l a n g u a g e i s p o s s i b i l i s t i c r a t h e r than prob-a b i l i s t i c i n n a t u r e. T h i s i n p l i e s t h a t a proposition , p, of the form "X i s F," where X i s t h e name of a v a r i a b l e a n d F i s a fuzzy subset of a universe of discourse U, translates i n PRUF i n t o an expression , P, which defines a procedure whose domain i s t h e set o f p o s s i b l y f u z z y r e l a t i o n s i n a database. (1) T h u s , (1) i m p l i e s t h a t t h e p o s s i b i l i t y t h a t X may t a k e t h e v a l u e u i s given by Poss{X=ul = TX(U) = VF(U)
TL;DR: The principal advantages of this technique are the new concept of direct simplification via essential fuzzy prime implicants (without generation of all of the fuzzy primeimplicants), and the fact that the algorithm is the first one to be suitable for efficient computer implementation.
Abstract: This paper is concerned with the study of simplification of fuzzy switching functions. A novel algorithm for generating all fuzzy prime implicants is introduced, followed by a new method of simplification of fuzzy switching functions. This algorithm is then reduced to a simple algorithm that produces only those fuzzy prime implicants that are essential. There areonly two other valid techniques for the minimization of fuzzy switching functions in the literature,(1,2) and those methods are not very suitable for computerized application. Thus, the principal advantages of this technique are the new concept of direct simplification via essential fuzzy prime implicants (without generation of all of the fuzzy prime implicants), and the fact that the algorithm is the first one to be suitable for efficient computer implementation.
TL;DR: The proposal raises a broad range of issues concerning the role of sophisticated information-processing techniques in the development of medical computing and it is suggested that a more evolutionary view of this development would be of greater benefit in the long run.
Abstract: Wechsler has advocated the use of fuzzy logic for medical diagnosis, but it is pointed out that simpler systems have proved more successful than is apparent from his paper. The proposal raises a broad range of issues concerning the role of sophisticated information-processing techniques in the development of medical computing. These issues are discussed and it is suggested that a more evolutionary view of this development would be of greater benefit in the long run.