An NC algorithm for recognizing tree adjoining languages
- New Jersey Institute of Technology, Newark, NJ (United States)
- Univ. of Nebraska, Lincoln, NE (United States)
A parallel algorithm is presented for recognizing the class of languages generated by tree adjoining grammars, a tree rewriting system which has applications in natural language processing. This class of languages is known to properly include all context-free languages; for example, the noncontext-free sets [l brace]a'b'c[r brace] and [l brace]ww[r brace] are in this class. It is shown that the recognition problem for tree adjoining languages can be solved by a concurrent read, concurrent write parallel random-assess machine (CRCW PRAM) in O(log n) time using polynomially many processors. Thus, the class of tree adjoining languages is in AC[sup 1] and hence in NC. This extends a previous result for context-free languages.
- OSTI ID:
- 7206512
- Journal Information:
- International Journal of Parallel Programming; (United States), Journal Name: International Journal of Parallel Programming; (United States) Vol. 21:2; ISSN IJPPE5; ISSN 0885-7458
- Country of Publication:
- United States
- Language:
- English
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