Construct State Modification in the Arabic Treebank
What it is about
The Arabic Treebank (ATB) marks a construct-state (iDafa) noun phrase as a NOUN with an NP complement, and the NP can nest. Modifiers, especially prepositional phrases, can then attach at any level of such a chain. Earlier work had blamed this for weak PP attachment on the ATB, because the English "base NP" rule that controls PP attachment does not hold. The authors extract 9,472 iDafas from about 100K words of ATB3 (ANNAHAR); 3,877 of them carry modifiers, most with exactly one (72%), and almost all are of depth three or less. A maximum-entropy model attaches each modifier to a level, with the constraint that later attachments are never deeper than earlier ones, and a dynamic program finds the best joint assignment. The best feature set (the tag of the modifier plus a lexical pair of modifier head and modified noun) reaches 80% accuracy on the dev-test split, against 39.7% for the depth-only baseline.
Ideas
- I1. Store a construct chain as one unit with numbered levels (0 = top, 1 = below, and so on), and let each modifier attach to a level rather than to "the nearest NP". In the tree reader (
world), a PP after the last noun of a chain should be recorded as attached to the chain, with its level, instead of to the last noun alone. - I2. A two-feature attachment classifier for the Hebrew construct chain (smichut): the category of the modifier plus the pair (chain head, modifier head), with the left-to-right depth constraint. It is small, rule-like and can be written as a table, so it is a good first test once
treebanks/hbotrees are available. - I3. Keep the paper's 39.7% depth-only baseline as a negative control: a rule that always attaches to the most common level should score far below any feature model. A result near 40% means the test is not measuring anything.
For Mova
I1 goes into the chain handling of Syntax: the clause and the sentence and 7. Syntax (the smichut and the genitive chain), and into the frame builder of world. I2 is a candidate model for The Noun, the Adjective and the Numeral once the MACULA-derived trees exist (tools/macula). I3 is a test to add to the same run.
Cite
@inproceedings{gabbard2008construct,
title = {{Construct State Modification in the Arabic Treebank}},
author = {Gabbard, Ryan and Kulick, Seth},
booktitle = {Proceedings of ACL-08: HLT, Short Papers},
year = {2008},
doi = {10.3115/1557690.1557750},
url = {https://doi.org/10.3115/1557690.1557750}
}References
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