Editing Expander graph (section)

===Expander walk sampling===
{{Main|Expander walk sampling}}
The [[Chernoff bound]] states that, when sampling many independent samples from a random variable in the range {{math|[−1, 1]}}, with high probability the average of our samples is close to the expectation of the random variable.  The expander walk sampling lemma, due to {{harvtxt|Ajtai|Komlós|Szemerédi|1987}} and {{harvtxt|Gillman|1998}}, states that this also holds true when sampling from a walk on an expander graph. This is particularly useful in the theory of [[derandomization]], since sampling according to an expander walk uses many fewer random bits than sampling independently.