The number of nonterminals in a linear conjunctive grammar is considered as a descriptional complexity measure of this family of languages. It is proved that a hierarchy collapses, and for every linear conjunctive grammar there exists and can be effectively constructed a linear conjunctive grammar that accepts the same language and contains exactly two nonterminals. This yields a partition of linear conjunctive languages into two nonempty disjoint classes of those with nonterminal complexity 1 and 2. The basic properties of the family of languages for which one nonterminal suffices are established. Nonterminal complexity of grammars in the linear normal form is also investigated.
| Original language | English |
|---|---|
| Pages (from-to) | 419-448 |
| Number of pages | 30 |
| Journal | Theoretical Computer Science |
| Volume | 320 |
| Issue number | 2-3 |
| DOIs | |
| State | Published - 14 Jun 2004 |
| Externally published | Yes |
ID: 41144387