A necessary and sufficient condition for a sequence 
to converge. The
Cauchy criterion is satisfied when, for all 
, there is a fixed number 
such that 
for all 
.
Cauchy Criterion
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Cite this as:
Weisstein, Eric W. "Cauchy Criterion." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/CauchyCriterion.html