ID/LP grammar

ID/LP Grammars are a subset of Phrase Structure Grammars, differentiated from other formal grammars by distinguishing between immediate dominance (ID) and linear precedence (LP) constraints. Whereas traditional phrase structure rules incorporate dominance and precedence into a single rule, ID/LP Grammars maintains separate rule sets which need not be processed simultaneously. ID/LP Grammars are used in Computational Linguistics.(1) A → B   C   D {displaystyle A ightarrow B C D} (2) B → D   C   A {displaystyle B ightarrow D C A} Lucy won the race.Ava told Sara to read a book.John suddenly screamed.John screamed suddenly. [ C , T , { c } , 0 ] , {displaystyle ,} [ F , T , { f } , 0 ] {displaystyle } [ S , C , { D , F } , 0 ] , {displaystyle ,} [ D , T , { d } , 1 ] , {displaystyle ,} [ F , T , { f } , 1 ] {displaystyle } [ S , C F , { D } , 0 ] , {displaystyle ,} [ D , T , { d } , 2 ] {displaystyle } [ S , C D F , ∅ , 0 ] {displaystyle } ID/LP Grammars are a subset of Phrase Structure Grammars, differentiated from other formal grammars by distinguishing between immediate dominance (ID) and linear precedence (LP) constraints. Whereas traditional phrase structure rules incorporate dominance and precedence into a single rule, ID/LP Grammars maintains separate rule sets which need not be processed simultaneously. ID/LP Grammars are used in Computational Linguistics. For example, a typical phrase structure rule such as S ⟶ NP VP {displaystyle {ce {S -> NP ; VP}}} , indicating that an S-node dominates an NP-node and a VP-node, and that the NP precedes the VP in the surface string. In ID/LP Grammars, this rule would only indicate dominance, and a linear precedence statement, such as N P ≺ V P {displaystyle NPprec VP} , would also be given. The idea first came to prominence as part of Generalized Phrase Structure Grammar; the ID/LP Grammar approach is also used in head-driven phrase structure grammar, lexical functional grammar, and other unification grammars. Current work in the Minimalist Program also attempts to distinguish between dominance and ordering. For instance, recent papers by Noam Chomsky have proposed that, while hierarchical structure is the result of the syntactic structure-building operation Merge, linear order is not determined by this operation, and is simply the result of externalization (oral pronunciation, or, in the case of sign language, manual signing). Immediate dominance is the asymmetrical relationship between the mother node of a parse tree and its daughters, where the mother node (to the left of the arrow) is said to immediately dominate the daughter nodes (those to the right of the arrow), but the daughters do not immediately dominate the mother. The daughter nodes are also dominated by any node that immediately dominates the mother node, however this is not an immediate dominance relation. For example the context free rule A → B   C   D {displaystyle A ightarrow B C D} , shows that the node labelled A (mother node) immediately dominates nodes labelled B, C, and D, (daughter nodes) and nodes labelled B, C, and D can be immediately dominated by a node labelled A. Linear precedence is the order relationship of sister nodes. LP constraints specify in what order sister nodes under the same mother can appear. Nodes that surface earlier in strings precede their sisters. LP can be shown in phrase structure rules in the form A → B   C   D {displaystyle A ightarrow B C D} to mean B precedes C precedes D, as shown in the tree below. A rule that has ID constraints but not LP is written with commas between the daughter nodes, for example A → B ,   C ,   D {displaystyle A ightarrow B, C, D} . Since there is no fixed order for the daughter nodes, it is possible that all three of the trees shown here are generated by this rule.