A set function is finitely additive if, given any finite disjoint collection of sets on which is defined,
Finite Additivity
See also
Countable Additivity, Countable Subadditivity, Disjoint Union, Finite Subadditivity, Set FunctionThis entry contributed by Christopher Stover
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References
Royden, H. L. and Fitzpatrick, P. M. Real Analysis. Pearson, 2010.Cite this as:
Stover, Christopher. "Finite Additivity." From MathWorld--A Wolfram Web Resource, created by Eric W. Weisstein. https://mathworld.wolfram.com/FiniteAdditivity.html