S. Shieber. Constraint-Based Grammar Formalisms. MIT Press, Cambridge, MA, 1992.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....some constraint based grammar formalisms, e.g. LFG (Kaplan Bresnan [14] GPSG (Gazdar et al. 12] and HPSG (Pollard Sag [18] 19] that employ a similar notion of constraints to specify syntactic structures. However, these constraints apply to context free rules, cf. Shieber [23] [24], rather than to certain structural relations between tree nodes. Nevertheless, such constraints constitute a particular type of local principles. Although the principle based approaches o er a number of formal bene ts they lack a detailed description of the trees speci ed. Since a principle ....

Shieber, S.M. (1992), Constraint-based grammar formalisms. MIT Press, Cambridge, MA.

....Pr( blue cry ) would seem to require even more labels like colorable noun phrases . Rather than letting the label set explode, it is better to consider a bigger class of grammars, which express these relations more succinctly but which are not so easily converted into HMM s: unification grammars [Sh] or compositional grammars [B G P] The need for grammars of this type is especially clear when we look at formalisms for expressing the grouping laws in vision: see figure 3. The further development of stochastic compositional grammars, both in language and vision, is one of the main challenges ....

S Shieber, Constraint-Based Grammar Formalisms, MIT Press, 1992.

.... representation of the data, and has advocated declarative, constraintbased representations (using feature structure matrices manipulated under unification) as an appropriate vehicle with which many technical problems in language description and computer manipulation of language can be solved [Shieber 92] One example of an infrastructure project based on Attribute Value Matrices (AVMs) is ALEP the Advanced Language Engineering Platform. ALEP aims to provide the NLP research and engineering community in Europe with an open, versatile, and general purpose development environment [Simkins 92, ....

S. Shieber. Constraint-Based Grammar Formalisms. MIT Press, Cambridge, MA, 1992.

.... representation of the data, and has advocated declarative, constraintbased representations (using feature structure matrices manipulated under unification) as an appropriate vehicle with which many technical problems in language description and computer manipulation of language can be solved [Shieber 92] One example of an infrastructure project based on Attribute Value Matrices (AVMs) is ALEP the Advanced Language Engineering Platform. ALEP aims to provide the NLP research and engineering community in Europe with an open, versatile, and general purpose development environment [Simkins 92, ....

S. Shieber. Constraint-Based Grammar Formalisms. MIT Press, Cambridge, MA, 1992.

....of GB because it is based on an LR parser for a context free grammar base. Other types of constraints have been used for example in Uni cation Grammars (UG) to de ne constraints over feature structures that are associated with the symbols of a context free or similar production based grammar [11, 8] and in Tree Adjoining Grammars (TAG) to de ne the domination relation in a tree and thus obtain a compact organization of the basic tree structures and a new characterization of the adjoining operation [14, 9, 10] In the case of UG, tabular parsing methods can be applied because of the ....

.... (TAG) to de ne the domination relation in a tree and thus obtain a compact organization of the basic tree structures and a new characterization of the adjoining operation [14, 9, 10] In the case of UG, tabular parsing methods can be applied because of the production based (context free) backbone [11, 7]. However, tabular parsers for grammars without explicit production rules have not been presented before. 2 Local Tree Constraints Constraints over local trees are considered to be formulas in a modal constraint language L 1 . The alphabet of L 1 consists of a countable set P = fp 1 ; p 2 ; ....

Stuart M. Shieber, Constraint-based grammar formalisms, MIT Press, Cambridge, Massachusetts, 1992.

....Systems 243 S. Wabash Ave. Chicago IL 60604 lytinen cs.depaul.edu, cphdnt ted.cs.depaul.edu Abstract Many algorithms for parsing unification grammars are extensions of well known context free parsing techniques, such as chart parsing. An example is Shieber s abstract parsing algorithm (Shieber, 1992), which can be viewed as an extension of Earley s algorithm. In this paper, we discuss a difficulty that exists in these algorithms in general, and in Shieber s algorithm in particular. The difficulty is that these algorithms produce what we call nonminimal derivations . Nonminimal ....

.... been developed including Generalized Phrase Structure Grammar (Gazdar, et al., 1985) PATR II (Shieber, 1986) Definite Clause Grammar (Pereira and Warren, 1980) and Headdriven Phrase Structure Grammar (Pollard and Sag, 1994) In an effort to formalize the common elements of unification grammars, Shieber (1992) developed a logic for describing these grammars, and specified an abstract parsing algorithm in the logic. The algorithm is quite general, in two ways: first, it is expressed as a set of deduction rules which, when applied, derive new items. 1 The rules merely specify what items are derivable; ....

Shieber, S. (1992). Constraint-based Grammar Formalisms.

....proof of this fact, based on a comparison of proof trees for the original and the transformed grammar, is given in [2] 7 His paper does not state termination conditions for the transformed program. Such termination conditions would probably involve some generalized notion of offline parsability [6, 5, 13]. By contrast, we prove termination only for DCGs which are OP in the original sense of Pereira and Warren, but this case seems to us to represent much of the core issue, and to lead to some direct extensions. For instance, the DCG transformation proposed here can be directly applied to guided ....

Stuart M. Shieber. Constraint-Based Grammar Formalisms. MIT Press, Cambridge, MA, 1992. 10

....claims that if syntax is a maximally efficient computational device for deriving LF representations from selections of lexical items, then its properties are constant (language invariant) modulo parametric variation 5 Shieber (1986) provides an introduction to unification based grammar. See also Shieber (1992) for discussion of constraint based grammar formalisms. See Koster (1987) for the earliest formulation of a monostratal representationalist (non derivational) version of GB. Rogers (1994) and Stabler (1992) develop different constraint based formalizations of GB. Brody (1995a) and (1995b) proposes ....

Shieber, S. (1992), Constraint-Based Grammar Formalisms, Bradford Books, MIT Press, Cambridge, MA.

....an argument of Johnson (1995) on nonlocal constraints, we claim that they are crucial in the P P based approaches to natural language and the big difference to other theories as for example HPSG. This is most clearly seen in phrase structure based implementations of these theories, e.g. in Shieber (1992) or Carpenter (1993) We can see the strong locality requirements since all the feature constraints are coupled to the phrase structure rules. In HPSG itself they are bound to the ID schemata. The constraints are only concerned with a node and its immediate children. They can be checked during the ....

Shieber, S. M. (1992). Constraint--Based Grammar Formalisms, MIT Press.

....representing input and output descriptions of the lexical rule, respectively. This enables lexical rules to be encoded in a type hierarchy and for relationships between rules to be expressed via type inheritance. The interpretation of lexical rules is analogous to that of grammar rules (e.g. Shieber, 1992), and such rules can be thought of as equivalent to unary grammar rules. Calcagno (1995) develops an algorithm for improving the notation for lexical rules by eliminating the need 3 Computational Linguistics Volume 1, Number 1 2 6 6 4 3rdsng lr IN : Theta base OUT : 3rdsng PHON ....

Shieber, Stuart. (1992). Constraint-based grammar formalisms. MIT Press, Cambridge, MA.

....formal grammars that describe both the assignment of trees to word strings, as well as the construction operations of complex SRL expressions from fundamental ones. During the last ten years, grammar formalisms have been developed which allow an expert to formulate very general grammar rules ( Shi92] Car92] covering 4 Type: COMMAND Content: TIME Geben Sie mir die Uhrzeit SRL Expression Reaction 11:30 pm Tree String Figure 1: Three steps of symbolic analysis and a processing result 5 large numbers of single rule instances. The details of linguistic description have been more and ....

S. Shieber. Constraint--Based Grammar Formalisms. MIT Press, 1992.

....such formalisms. In one school, which is currently represented most visibly by LFG [Kap89] the parsing process has a context free backbone, and the unification based formalism is used as a constraintenforcement mechanism to weed out incorrect parses. Both Johnson s [Joh88] and Shieber s books [Shi92] describe recent theoretical efforts in this direction. In the other school, which is currently represented most visibly by HPSG [PS87] the context free backbone is eschewed entirely. Rather, the entire parsing process becomes one of constraint satisfaction. This is a rather intriguing idea, but ....

Shieber, S. M., Constraint-Based Grammar Formalisms, MIT Press, 1992.

.... (42) problematic rather than (41) over the one we gave in Briscoe et al. 1990) where the converse applied) The diculty seems comparable to the problem of cross categorial coordination from a syntactic viewpoint for which a number of solutions have been proposed (see e.g. Sag et al. 1985; Shieber, 1992; Cooper, 1991) Conjunction is licensed in examples such as (43) if the syntactic descriptions of each of the conjuncts independently uni es with the subcategorisation requirement of the verb, despite the fact that these descriptions will not unify with each other: 43) Tigger became famous and ....

....of Briscoe et al. 1990) and Pustejovsky (1993) is capable of capturing many facts of co predication . However, our account requires extension in order to deal with the cases of non constituent coordination discussed in x5.1, in line with other constraint based approaches to coordination (e.g. Shieber, 1992). Furthermore, it needs to be supplemented with a pragmatic account of cohesive co predication along the lines of Nunberg (this volume) as discussed in x5. We have argued that sense extensions are semi productive related sense changes: we cannot simply list all the extended senses in the ....

Shieber, S. M. (1992) Constraint-based grammar formalisms, MIT Press, Cambridge, Mass..

....down to the input word so that unsuccessful rule applications are pruned at the earliest time. However, in the context of unification based parsing, left recursive grammars have the formal power of a Turing machine, therefore detection of all infinite loops due to left recursion is impossible (Shieber, 1992). So, top down constraints must be weakened in order for parsing to be guaranteed to terminate. In order to solve the nontermination problem, Shieber (1985) proposes restrictor , a statically predefined set of features to consider in propagation, and restriction, a filtering function which removes ....

....by the detection function, and will be ignored in top down propagation. Using restrictor , only the relevant features particular to the propagation path are ignored, thus top down constraints are maximally propagated. 2 Notation We use notation from the PATR II formalism (Shieber, 1986) and (Shieber, 1992). Directed acyclic graphs (dags) are adopted as the representation model. The symbol : is used to represent the equality relation in the unification equations, and the symbol Delta used in the form of p1 Delta p2 represents the path concatenation of p1 and p2. The subsumption relation is ....

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Shieber, S. (1992). Constraint-based Grammar Formalisms.

....and Shieber (1984) or Carpenter (1992, pp. 204 206) We show that these definitions are equivalent and that none of them supports compositionality. 3. 1 Basic notions We assume familiarity with theories of feature structure based unification grammars, as formulated by, e.g. Carpenter (1992) or Shieber (1992). Grammars are defined over typed feature structures (TFSs) which can be viewed as generalizations of first order terms (Carpenter, 1991) TFSs are partially ordered by subsumption, with the least (or most general) TFS. A multi rooted structure (MRS, see Sikkel (1997) or Wintner and Francez ....

Shieber, Stuart M. 1992. Constraint-Based Grammar Formalisms. MIT Press, Cambridge, Mass.

....robustness, fluency, and modularity confront researchers addressing the natural language processing problems necessary for ubiq32 uitous information. These issues can be addressed through the use of systems of constraints as the underlying method for encoding the structures of natural language [98]. ffl Robustness: Natural language processing systems tend to be fragile, especially in the face of novel or unknown aspects of language. Existing grammatical formalisms assume that all constraints are categorical as opposed to defeasible in some sense, leading to fragile behavior. Recently, ....

Stuart M. Shieber. Constraint-Based Grammar Formalisms. MIT Press, Cambridge, Massachusetts, 1992.

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S. Shieber. Constraint-Based Grammar Formalisms. MIT Press, Cambridge, MA, 1992.

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Shieber S. (1992) Constraint-Based Grammar Formalisms, MIT Press. 9

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Stuart M. Shieber. 1992. Constraint-Based Grammar Formalisms. MIT Press, Cambridge, MA.

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Shieber S. (1992) Constraint-Based Grammar Formalisms, MIT Press. 9

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Shieber S. (1992), Constraint-Based Grammar Formalisms, MIT Press. 24

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Shieber S. (1992) Constraint-Based Grammar Formalisms, MIT Press.

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Shieber S. (1992) Constraint-Based Grammar Formalisms, MIT Press.

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Shieber, S.M. (1992), Constraint-Based Grammar Formalisms. Parsing and Type Inference for Natural and Computer Languages. MIT Press, Cambridge, MA.

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Stuart M. Shieber. 1992. Constraint-Based Grammar Formalisms. MIT Press, Cambridge, Mass.

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