Algebra of fuzzy numbers.

An algebra of ordered fuzzy numbers (OFN) is defined. It enables handling fuzzy inputs in a quantitative way, exactly in the same way as for real numbers. Two additional structures, algebraic and normed (topological), are introduced, which make it possible to define a general form of defuzzyfication operators if fuzzy rules are used in a decision process. A useful implementation of a fuzzy calculator is given which allows counting with OFNs of general type membership relations.