Indicator Function

An Indicator Function is a Binary Function that indicates the presence of some predetermined Pattern.

• AKA: Indicator, Characteristic Function.
• See: Characteristic Function, Set Member.

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References

2009

• http://en.wikipedia.org/wiki/Indicator_function
  • In mathematics, an indicator function or a characteristic function is a function defined on a set [math]\displaystyle{ X }[/math] that indicates membership of an element in a subset A of X, having the value 1 for all elements of [math]\displaystyle{ A }[/math] and the value 0 for all elements of [math]\displaystyle{ X }[/math] not in A.

2005

• (Collins & Koo, 2005) ⇒ Michael Collins, and Terry Koo. (2005). “Discriminative Reranking for Natural Language Parsing.” In: Computational Linguistics, 31(1) doi:10.1162/0891201053630273
  • … It is common (e.g., see (Ratnaparkhi 96)) for each feature s to be an indicator function. For example, one such feature might be Theta₁₀₀₀(h,t) = 1 if current word w<subi is the and t=DT otherwise.

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