Nuprl Lemma : empty_support 4,23

n:, f:(n). (x:n. f(x) = 0)  sum(f(x) | x < n) = 0 
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DefinitionsAB, A, False, P  Q, sum(f(x) | x < k), x(s), {i..j}, x:A. B(x), t  T, , Prop, SQType(T), {T}, x. t(x), P  Q, P & Q, P  Q
Lemmassum constant, sum functionality, sum wf, nat wf, int seg wf

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