Encyclopedia > Greibach normal form

  Article Content

Greibach normal form

A context-free grammar is in Greibach normal form (GNF) iff all production rules are of the form:
A -> αX
where A is a nonterminal symbol, α is a terminal symbol and X is (possibly empty) sequence of nonterminal symbols.

No grammar in GNF can generate the null string. Conversely, every context-free grammar which does not generate the null string can be transformed into an equivalent grammar in Greibach normal form. This can be used to prove that every context-free language can be accepted by a non-deterministic pushdown automaton.

All Wikipedia text is available under the terms of the GNU Free Documentation License

  Search Encyclopedia

Search over one million articles, find something about almost anything!
  Featured Article
U.S. presidential election, 1804

... Votes) Thomas Jefferson (W) 162 Democratic-Republican George Clinton (162) Charles C. Pinckney[?] 14 Federalist Rufus King (14) Other ...

This page was created in 35.1 ms