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9.9.  Additional Operators

The unary postfix operators ? and + do not allow us to define additional languages, but they often make it easier to express languages.

R? stands for [xi] | R

R+ stands for L(R) [cup] L(RR) [cup] L(RRR) ...


%  egrep '(aa|bb)(e|o)(c|d)' words

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Last modified: 27/July/98 (12:14)