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Unformatted text preview: l in to at most l ! classes. For 1 i ( l !), let z i be the shortest string in L such that  z i  l, and  z i  l i mod ( l !) . Notice that for some i , there might not exists some z i that satisfy above equation. We use S to denote the set that contains all the i such that z i exists. Now we can write L by the following regular expression, L = { x   x  l,x L } i S z i ( a ( q !) ) * . 1...
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 Spring '09
 EdmundM.Clarke

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