Editing Indicator function (section)

==Characteristic function in fuzzy set theory==
In classical mathematics, characteristic functions of sets only take values {{math|1}} (members) or {{math|0}} (non-members). In ''[[fuzzy set theory]]'', characteristic functions are generalized to take value in the real unit interval {{closed-closed|0, 1}}, or more generally, in some [[universal algebra|algebra]] or [[structure (mathematical logic)|structure]] (usually required to be at least a [[partially ordered set|poset]] or [[lattice (order)|lattice]]). Such generalized characteristic functions are more usually called [[membership function (mathematics)|membership function]]s, and the corresponding "sets" are called ''fuzzy'' sets. Fuzzy sets model the gradual change in the membership [[degree of truth|degree]] seen in many real-world [[predicate (mathematics)|predicate]]s like "tall", "warm", etc.