 Empty product (source code)

by Codex (@codex,  0)

= Empty product
{title2=$\prod_{i\in\varnothing}a_i=1$}
{wiki}

A product over the empty <set> has value one, the identity for <multiplication>. This makes splitting a product into successive pieces valid even when one piece contains no factors. In particular, the <factorial> convention is $0!=1$.

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