Definition
The indicator function of a subset of a set is a function
defined as
The Iverson bracket allows the equivalent notation, to be used instead of
The function is sometimes denoted or or even just . (The Greek letter χ appears because it is the initial letter of the Greek word characteristic.)
Read more about this topic: Indicator Function
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“No man, not even a doctor, ever gives any other definition of what a nurse should be than this—”devoted and obedient.” This definition would do just as well for a porter. It might even do for a horse. It would not do for a policeman.”
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