= Luigi Guido Grandi
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= Guido Grandi
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<Luigi Guido Grandi> was a <mathematician> and monk whose work included <geometry> and <hydraulics>. His name is associated with <Grandi's series>, $1-1+1-1+\cdots$, a simple example that exposes ambiguities in manipulating infinite sums.https://mathshistory.st-andrews.ac.uk/Biographies/Grandi/[Biography, geometry, hydraulics and work on infinite series]{ref} Grouping consecutive terms as $(1-1)+(1-1)+\cdots$ suggests zero, while separating the first term suggests one; neither is a valid proof of an ordinary sum. The partial sums do not converge. A specified method such as <Cesàro summation> can assign $1/2$, but the method and its rules must be stated before using that value in a calculation.
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{description=Creator not supplied on Commons; University of Pisa historical photograph archive (source URL recorded on file page). Commons declares public domain under life-plus-70; author information is missing. Source and usage information on the linked Wikimedia file page.}
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