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Formal Definition: first(X), follow(X), nullable

first(X), follow(X) and nullable are the smallest sets with the following properties:
\begin{program} For~each~production~X~=~Y1~..~Yk,~$1 \le i$,~~$j \le k$: \\ ~~~~... ...ullable \\ ~~~~~~~~~~~~~~~~follow(Yi)~=~follow(Yi)~$\cup$~first(Yj)\end{program}


Christoph Zenger
4/6/2000