A homomorphism theorem for weighted context-free grammars
β Scribed by Donald F. Stanat
- Publisher
- Elsevier Science
- Year
- 1972
- Tongue
- English
- Weight
- 731 KB
- Volume
- 6
- Category
- Article
- ISSN
- 0022-0000
No coin nor oath required. For personal study only.
β¦ Synopsis
Productions of a context-free grammar can be given coefficients from semirings, inducing weights for both derivations in the grammar and strings over the terminal alphabet. For a weighted context-free grammar in Greibach normal form, the weight of any string, as well as the set of derivations of the string, may be determined from the image under a homomorphism which maps each terminal symbol to a polynomial. The definition of the homomorphism is a straightforward function of the productions. Some examples of interesting semiring structures are included.
π SIMILAR VOLUMES
A practical method is presented for the automatic generation of a non-recursive context-free grammar (cfg) from a set of strings that the cfg is required to be capable of producing. The method is efficient in computing time by comparison with enumerative methods.