Difference between revisions of "ID/LP rules"

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===Example===
 
===Example===
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Wenn man kontextfreie Phrasenstrukturregeln als Wohlgeformtheitsbedingungen für (lokale) Bäume auffasst, dann lässt eine Regel der Form ''X'' <math>\rightarrow</math> <math>Y_1</math> <math>Y_2</math> ... <math>Y_n</math> genau einen Baum zu. Für diesen Baum gilt: (a) Die Kategorie <math>X</math> dominiert die Kategorien <math>Y_1</math> ... <math>Y_n</math> und (b) Die Kategorie <math>Y_i </math> steht vor der Kategorie <math>Y_{i+1}</math> (für i = 1, ... n-1).  
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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).  
  
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Eine ID-Regel ''X'' <math>\rightarrow</math> <math>Y_1,</math> <math>Y_2,</math> ..., <math>Y_n </math> dagegen lässt alle Bäume zu, in denen ''X'' die auf der rechten Regelseiten aufgeführten Kategorien dominiert, unabhängig davon, in welchen Reihenfolge diese Kategorien realisiert werden. LP-Regeln schränken die Menge der durch eine ID-Regel zugelassenen Bäume ein: Jeder Baum, der einer der durch sie festgelegten Linearisierungsvorschriften nicht genügt, wird verworfen.
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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===
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Replacing contextfree 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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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).
 
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).
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===Other Languages===
 
===Other Languages===
 
* German [[ID/LP-Regeln]]
 
* German [[ID/LP-Regeln]]
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[[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

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