The intellectual origins of the idea of fuzzy concepts have been traced back to a diversity of famous and less well known thinkers including Eubulides, Plato, Cicero, Georg Wilhelm Friedrich Hegel, Karl Marx, Friedrich Engels, Friedrich Nietzsche, Max Black,[REF]Jan Łukasiewicz, Alfred Tarski, Stanisław Jaśkowski[REF] and Donald Knuth [REF].
In fact, the German scholar Dieter Klaua also published a German-language paper on fuzzy sets in 1965,[REF] but he used a different terminology (he referred to "many-valued sets") [REF].