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Autor(in)
Alle anzeigen
Datum
2023-12Typ
- Conference Paper
ETH Bibliographie
yes
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Abstract
The left-corner transformation (Rosenkrantz and Lewis, 1970) is used to remove left recursion from context-free grammars, which is an important step towards making the grammar parsable top-down with simple techniques. This paper generalizes prior left-corner transformations to support semiring-weighted production rules and to provide finer-grained control over which left corners may be moved. Our generalized left-corner transformation (GLCT) arose from unifying the left-corner transformation and speculation transformation (Eisner and Blatz, 2007), originally for logic programming. Our new transformation and speculation define equivalent weighted languages. Yet, their derivation trees are structurally different in an important way: GLCT replaces left recursion with right recursion, and speculation does not. We also provide several technical results regarding the formal relationships between the outputs of GLCT, speculation, and the original grammar. Lastly, we empirically investigate the efficiency of GLCT for left-recursion elimination from grammars of nine languages. Code: https://github.com/rycolab/left-corner Mehr anzeigen
Persistenter Link
https://doi.org/10.3929/ethz-b-000650674Publikationsstatus
publishedExterne Links
Buchtitel
Proceedings of the 2023 Conference on Empirical Methods in Natural Language ProcessingSeiten / Artikelnummer
Verlag
Association for Computational LinguisticsKonferenz
Organisationseinheit
09682 - Cotterell, Ryan / Cotterell, Ryan
09462 - Hofmann, Thomas / Hofmann, Thomas
Zugehörige Publikationen und Daten
Is supplemented by: https://github.com/rycolab/left-corner
ETH Bibliographie
yes
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