On Fri, Aug 12, 2011 at 4:34 PM, Sebastian Fischer <fisc...@nii.ac.jp>wrote:
> > I can easily understand how + can be built but am having trouble with > > building ? (zero or one). > > If there is a regular expression e for the empty word, one can define ? as > > a? = e | a > > If there is a regular expression o that never matches one can define e as > > e = o* > > If there are character classes one can define o as > > o = [] > > Apart from that, I have no idea.. > > Sebastian > Thanks Sebastian ... this is what I was asking for. I'll try and digest it. Regards, Kashyap
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