Difference between revisions of "ID/LP rules"
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− | + | [[Generalized Phrase Structure Grammar]] (GPSG) uses [[ID-rule|ID-rules]] (''immediate dominance rules'') and [[LP-rule|LP-rules]] (''linear precedence rules'') instead of context-free phrase structure rules to describe hierarchical and sequential aspects of linguistic units separately. | |
===Example=== | ===Example=== | ||
− | + | Context-free phrase structure rules can be interpreted as well-formedness conditions for [[local tree|local trees]]. A rule like ''X'' <math>\rightarrow</math> <math>Y_1</math> <math>Y_2</math> ... <math>Y_n</math> licences exactly one tree. This tree is characterised by two facts: (i). The root labelled <math>X</math> (directly) dominates the nodes labelled <math>Y_1</math> ... <math>Y_n</math> and (ii). The node labelled <math>Y_i </math> precedes node <math>Y_{i+1}</math> (for i = 1, ... n-1). | |
− | + | An ID-rule ''X'' <math>\rightarrow</math> <math>Y_1,</math> <math>Y_2,</math> ..., <math>Y_n </math> on the other hand, licences all trees in which ''X'' dominates the other categories, no matter in which order these categories appear. An LP-rule restrains the set of local trees licenced by an ID-rule: Each tree which violates the LP-rule is disregarded. | |
===Comment=== | ===Comment=== | ||
− | + | Replacing context-free rules by ID- and LP-rules was motivated by the idea that by this division of labor it is possible to state important generalization concerning the word order (constituent order) for a given natural language ''explicitly''. | |
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+ | Each ID/LP-syntax can be converted into a [[strongly equivalent]] context-free phrase structure syntax. As the linear restrictions expressed by LP-rules are interpreted ''globally'' (no local tree licenced by any ID-rule may violate any of the LP-rules), there are context-free grammars which can not be converted into a strongly equivalent ID/LP-grammar (though into a [[weakly equivalent]] ID/LP-syntax). | ||
===Other Languages=== | ===Other Languages=== | ||
* German [[ID/LP-Regeln]] | * German [[ID/LP-Regeln]] | ||
− | {{dc}} | + | {{dc}}{{ref}} |
[[Category:Syntax]] | [[Category:Syntax]] |
Latest revision as of 20:45, 3 July 2014
Generalized Phrase Structure Grammar (GPSG) uses ID-rules (immediate dominance rules) and LP-rules (linear precedence rules) instead of context-free phrase structure rules to describe hierarchical and sequential aspects of linguistic units separately.
Example
Context-free phrase structure rules can be interpreted as well-formedness conditions for local trees. A rule like X <math>\rightarrow</math> <math>Y_1</math> <math>Y_2</math> ... <math>Y_n</math> licences exactly one tree. This tree is characterised by two facts: (i). The root labelled <math>X</math> (directly) dominates the nodes labelled <math>Y_1</math> ... <math>Y_n</math> and (ii). The node labelled <math>Y_i </math> precedes node <math>Y_{i+1}</math> (for i = 1, ... n-1).
An ID-rule X <math>\rightarrow</math> <math>Y_1,</math> <math>Y_2,</math> ..., <math>Y_n </math> on the other hand, licences all trees in which X dominates the other categories, no matter in which order these categories appear. An LP-rule restrains the set of local trees licenced by an ID-rule: Each tree which violates the LP-rule is disregarded.
Comment
Replacing context-free rules by ID- and LP-rules was motivated by the idea that by this division of labor it is possible to state important generalization concerning the word order (constituent order) for a given natural language explicitly.
Each ID/LP-syntax can be converted into a strongly equivalent context-free phrase structure syntax. As the linear restrictions expressed by LP-rules are interpreted globally (no local tree licenced by any ID-rule may violate any of the LP-rules), there are context-free grammars which can not be converted into a strongly equivalent ID/LP-grammar (though into a weakly equivalent ID/LP-syntax).
Other Languages
- German ID/LP-Regeln
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