Zadeh, L. A. Fuzzy sets. (English) Zbl 0139.24606 Inf. Control 8, 338-353 (1965). A fuzzy set is a “set” of elements with a continuum of “grades of membership”. The rigorous definition is: let \(X\) be a set of objects (elements); a fuzzy set \(A\) in \(X\) is defined by a “membership (characteristic) function” \(f_A\), which associates with each element \(x\in X\) a real number \(f_A(x)\in [0,1]\). The value \(f_A(x)\) of \(f_A\) at \(x\) represents the grade of membership of \(x\) in \(A\). If \(A\) is an “ordinary” set, its membership function \(f_A\) can take on only the values 0 and 1: \(x\in A\Leftrightarrow f_A(x) = 1\) and \(x\neq A \Leftrightarrow f_A(x)=0\). Various usual notions are extended to such sets (for instance, the notions of union, intersection and convexity). Reviewer: N. C. A. da Costa Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Cited in 64 ReviewsCited in 6434 Documents MSC: 03E72 Theory of fuzzy sets, etc. Keywords:fuzzy sets; continuum of grades of membership; membership characteristic function; separation theorem for convex fuzzy sets PDF BibTeX XML Cite \textit{L. A. Zadeh}, Inf. Control 8, 338--353 (1965; Zbl 0139.24606) Full Text: DOI