# Stochastic grammar

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A **stochastic grammar** (**statistical grammar**) is a grammar framework with a probabilistic notion of grammaticality:

- Stochastic context-free grammar
- Statistical parsing
- Data-oriented parsing
- Hidden Markov model
- Estimation theory

The grammar is realized as a language model. Allowed sentences are stored in a database together with the frequency how common a sentence is.^{[1]} Statistical natural language processing uses stochastic, probabilistic and statistical methods, especially to resolve difficulties that arise because longer sentences are highly ambiguous when processed with realistic grammars, yielding thousands or millions of possible analyses. Methods for disambiguation often involve the use of corpora and Markov models. "A probabilistic model consists of a non-probabilistic model plus some numerical quantities; it is not true that probabilistic models are inherently simpler or less structural than non-probabilistic models."^{[2]}

## Examples

A probabilistic method for rhyme detection is implemented by Hirjee & Brown^{[3]} in their study in 2013 to find internal and imperfect rhyme pairs in rap lyrics. The concept is adapted from a sequence alignment technique using BLOSUM (**BLO**cks **SU**bstitution **M**atrix). They were able to detect rhymes undetectable by non-probabilistic models.

## See also

- Colorless green ideas sleep furiously
- Computational linguistics
- L-system#Stochastic grammars
- Stochastic context-free grammar
- Statistical language acquisition

## References

**^**Steve Young; Gerrit Bloothooft (14 March 2013).*Corpus-Based Methods in Language and Speech Processing*. Springer Science & Business Media. pp. 140–. ISBN 978-94-017-1183-8.**^**John Goldsmith. 2002. "Probabilistic Models of Grammar: Phonology as Information Minimization." Phonological Studies #5: 21–46.**^**Hirjee, Hussein; Brown, Daniel (2013). "Using Automated Rhyme Detection to Characterize Rhyming Style in Rap Music" (PDF).*Empirical Musicology Review*.