S. M. Shieber, Constraint-Based Grammaar Formalisms. Parsing and Type Inference for Natural and Computer Languages. A Bradford Book. Cambridge, Mass.: The MIT Press, 1992.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....In a second step, these fragments are combined into bigger units obeying semantic and pragmatic constraints, the applicability of which is checked by valency and case frames of the lexical units. Currently, we implement chunk grammars in a unification grammar formalism derived from PATR II [Shi92] and augmented by DRS composition operators. In parsing with unification grammars, constraints are expressed as path equations. Instead of representing feature structures in a separate formalism, they could as well be expressed in DL. As a little experiment with CLASSIC showed, unification can ....

S. M. Shieber, Constraint-Based Grammaar Formalisms. Parsing and Type Inference for Natural and Computer Languages. A Bradford Book. Cambridge, Mass.: The MIT Press, 1992.

....left to the right. The definition of subsumption, however, requires that equal subtrees are extended in the same manner. a a a a a a a f g f g g Subsumption constraints have been considered in the context of unification based grammars to model coordination phenomena in natural language [21, 19, 44]. There, one wants to express that two feature structures representing different parts of speech share common properties. For example, the analysis of programming and linguistics in the phrase Feature constraints are good for [ NP programming] and [ NP linguistics] should share (but might ....

Steward Shieber. Parsing and Type Inference for Natural and Computer Languages. SRI International Technical Note 460, Stanford University, March 1989.

.... Efficient Implementation of PATR for Categorial Unification Grammar Todd Yampol Stanford University Lauri Karttunen Xerox PARC and CSLI i Introduction This paper describes C PATR, a new C im plementation of the PATR II formalism [4, 5] for unification based grammars. It includes innovations that originate with a project for developing an efficient translator from En glish to first order logic [2] most notably the extension of the standard unification algo rithm for list values [section 3] In addition the uni:fier and a ....

Shieber, Stuart, Parsing and Type Infer- ence for Natural and Computer Languages, Technical Note 460, Stanford Research International,

....motivations our presentation is lacking. Other state of the art guides into this fascinating area of research are [37] and [35] Johnson s thesis [16] gives a formal account of an lfg like formalism and investigates a feature constraint language with disjunctions and negations. Shieber s thesis [45] gives a rigorous formalization of the patr formalism. For instance, the word drink can be used as transitive verb or as noun. 10 3 Feature Algebras and Feature Graphs In this section we define the possible interpretations of the feature descriptions to be discussed. These interpretations ....

....acyclicity condition. Another interesting extension are subsumption constraints making the subsumption preorder of feature algebras syntactically available. A subsumption constraint takes the form x Delta v y and has the solutions (x Delta v y) fff 2 ASS[I] j ff(x) ff(y)g: Shieber [45] discusses the usefulness of subsumption constraints for dealing with coordination problems. Dorre and Rounds [10] show that the satisfiability of conjunctions of feature equations and subsumption constraints is undecidable. This problem is closely related to the semi unification problem for ....

S. M. Shieber. Parsing and type inference for natural and computer languages. Technical Note 460, SRI International, Artificial Intelligence Center, Menlo Park, CA, Mar. 1989.

.... practice, this property does not necessarily entail that finding a program P to exploit will be obviousfi 4 For instance, offiine parsable grammars [9] can be shown to possess a finitely enumerable parsing problem, but algorithms which are able to make use of this property are by no means trivial [9, 13, 3]. 5 Discoverability If r is not finitely enumerable on 6P, it may still be discoverable on 6P. By definition, this means that it is possible to find a program P such that, for any given (ground) value of the p parameter, if there is no value y of the g parameter corresponding to , then the ....

Stuart M. Shieber. Parsing and type inference for natural and computer languages. Technical note 460, SRI International, Menlo Park, CA, 1989. (Ph.D. dissertation, Department of Computer Science, Stanford University).

....algorithm is coherent in the sense that the generation process will not augment an input semantic expression. 22 2.3. 2 The Head driven Approach of Van Noord and Shieber et al. In order to overcome the restriction of semantic monotonicity and to achieve a goal directed generation strategy [Shieber et al. 1989] proposed a new generation algorithm, called the semantic head driven generation algorithm (SHDG , for short) which has later been extended to parsing by [VanNoord, 1993] A similar headdriven algorithm has been developed by [Calder et al. 1989] however, restricted to use in unification based ....

....left hand side. Thus, for generation it would be more appropriate to choose and complete this element first before the first element of the right hand side is processed, because the head element provides important in formation for its argument . To be able to get this kind of goal directedness [Shieber et al. 1989] proposes a semantic head first selection rule in the case of generation. For the identification of possible semantic heads, a subset of the rules of a grammar is distinguished, called the chain rules, in which the semantics of some righthand side element is identical to the semantics of the ....

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S.M. Shieber. Parsing and Type Inference for Natural and Computer Languages. PhD thesis, Standford University, SRI International Technical note 460, 1989.

....principles into phrase structure rules in a precompilation step before runtime. 2 Parsing as Deduction There is a close analogy between parsing and the construction of proofs so much so that parsing (or generation, for that matter) can be unpacked as deduction, c.f. Pereira and Warren, 1983; Shieber, 1989 ] and the categorial grammar literature. Here we introduce our description format by way of example. Let G = hT; N; S; Ri be a CF PSG where T and N are disjoint sets of terminal and non terminal symbols, respectively. S is the start symbol and R a set of productions. A simple left corner approach ....

S.M. Shieber. Parsing and type inference for natural and computer languages. Technical Report Technical Note 460, SRI International, Menlo Park, California, 1989.

.... grammar theories has begun to play an important role within the field of natural language processing, e.g. lfg [ Bresnan, 1982 ] hpsg [ Pollard and Sag, 1994 ] In the last few years constraint based formalisms have undergone a rigorous formal investigation (consider for example [ Shieber, 1989; Smolka, 1992 ] This has led to a general characterisation of constraint based formalisms where feature structures are considered to constitute a semantic domain and constraints are considered syntactic representations of such semantic structures . This logical view has several advantages. On ....

S. M. Shieber. Parsing and Type Inference for Natural and Computer Languages. PhD thesis, Stanford University, SRI International Technical note 460, 1989.

....and their combination would be quite fruitful. One option for specifying lexical (semantic) representations is DATR [ Evans and Gazdar, 1996 ] A representation in DATR takes the form of a set of path equations which are basically attribute value pairs as in constraint based approaches [ Shieber, 1992 ] In this respect lexical entries in DATR are similar to the ones in [ Copestake and Briscoe, 1993 ] These could in fact be expressed in DATR because it is not restricted to any particular theory. It is a representation language for lexical knowledge with the possibility of defining (multiple) ....

....it is not restricted to any particular theory. It is a representation language for lexical knowledge with the possibility of defining (multiple) inheritance and defaults. The representation of systematic polysemy which concerns us here most can be handled in DATR by using re entrance (see e.g. Shieber, 1992 ] The representation in Figure 2.6 illustrates the systematic polysemy of fruits like cherry, mango, etc. This class of lexical items is systematically polysemous between a fruit, the tree that grows the fruit and the wood produced by the tree (from [ Evans and Gazdar, 1996 ] after a proposal ....

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

....particle verbs like das Treffen findet morgen im DFKI statt with logical form morgen(stattfinden(treffen, DFKI) 2.3. 2 The Head driven Approach of Van Noord and Shieber et al. In order to overcome the restriction of semantic monotonicity and to achieve a goal directed generation strategy [ Shieber et al. 1989 ] proposed a new generation algorithm, called the semantic head driven generation algorithm (shdga, for short) which has later been extended to parsing by [ VanNoord, 1993 ] A similar headdriven algorithm has been developed by [ Calder et al. 1989 ] however, restricted to use in ....

....left hand side. Thus, for generation it would be more appropriate to choose and complete this element first before the first element of the right hand side is processed, because the head element provides important information for its argument . To be able to get this kind of goal directedness [ Shieber et al. 1989 ] proposes a semantic head first selection rule in the case of generation. For the identification of possible semantic heads, a subset of the rules of a grammar is distinguished, called the chain rules, in which the semantics of some righthand side element is identical to the semantics of the ....

[Article contains additional citation context not shown here]

S. M. Shieber. Parsing and Type Inference for Natural and Computer Languages. PhD thesis, Standford University, SRI International Technical note 460, 1989.

....(1991) in arguing against syntactic based reconstruction for VP ellipsis. 36) The formalisms are thus more aptly referred to as information or constraint based rather than unification based, and we will do so here. refer to the formalisms as information or constraint based] from text of Shieber (1989, p. 41) 37) It is possible that this result can be derived from some independent principle, but I know of no theory that does so. derives this result from some independent principle] from text of Mohanan (1983, p. 664) In these examples, the source clause is not of a suitable form at the ....

Shieber, Stuart M. 1989. Parsing and Type Inference for Natural and Computer Languages. Ph.D.

....of TAGs as a constraint based formalism (Vijay Shanker, 1992) The second is a means of reducing the size of the presentation of a Lexicalized TAG (LTAG) grammar through structure sharing (Vijay Shanker Schabes, 1992) 1. 1 Descriptions of trees and TAG Constraint based parsers (Shieber, 1986; Shieber, 1989) operate by building, on the basis of the input, a collection of constraints on the structure interpreting that input, a phrase structure tree for instance. One useful way to think of this process is that the parser starts with a completely general description one that is satisfied by every ....

Shieber, S. M. (1989). Parsing and type inference for natural and computer languages. Technical Report 460, SRI International. p. 147.

....agentive and telic roles. Examples for each in the case of book are: a book can also be seen as a physical object 2 , a book has pages, a cover and more, the existence of a book is caused by writing it and its purpose is to be read. We can represent this in a constraint based fashion [17]: 2 6 6 6 6 6 6 6 6 6 4 book qualia struct = 2 6 6 6 4 formal = phys obj constitutive = pages, cover, agentive = write telic = read 3 7 7 7 5 3 7 7 7 7 7 7 7 7 7 5 Figure 1: Qualia Structure for book In the case of model the formal role would be filled by an artifact, the ....

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

....variable or a terminal, C is a constraint containing no free variables other than those that occur in X Gamma Y 1 Y 2 Delta Delta Delta Y n , and no variable occurs twice in X Gamma Y 1 Y 2 Delta Delta Delta Y n . 2 Figure 2 gives a constraint grammar that is similar to the one found in [Shieber, 1989]. Here, and throughout the paper, start rules are written with the symbol S Gamma . Observe that without disjunction, it would take three rules to capture the effect of (R7) In what follows it is useful to extend the domain of every assignment A by stipulating that A(w) w for every terminal ....

....in the language of the constraint grammar G if, and only if, from the trivial trees of G the constraint grammar parsing rule can build an initial admissible parse tree whose yield is s. 7 Discussion The two pieces of work most closely related to this work are the Ph.D. theses of Johnson [1988] and Shieber [1989]. Though the formalism presented by Johnson is very similar to constraint grammar, his work focuses much less on parsing and much more on testing the satisfiability of constraints. Shieber s formalism is also very similar to constraint grammar, but when he comes to the topic of parsing he abandons ....

Stuart M. Shieber. Parsing and type inference for natural and computer languages. Technical Report 460, SRI International, March 1989.

.... the term constraintbased grammar theories play an important role within the field of natural language processing, e.g. lfg [ Bresnan, 1982 ] hpsg [ Pollard and Sag, 1994 ] In the last few years constraint based formalisms have undergone a rigorous formal investigation (consider for example [ Shieber, 1989; Smolka, 1988; Smolka, 1992 ] This has led to a general characterisation of constraint based formalisms where feature structures are considered to constitute a semantic domain and constraints are considered syntactic representations of such semantic structures . This logical view has several ....

S. M. Shieber. Parsing and Type Inference for Natural and Computer Languages. PhD thesis, Stanford University, SRI International Technical note 460, 1989.

....addition of features makes the task of describing and generating actual language fragments much simpler [74] Two other significant contributions to the theory of features must be mentioned. One important influence is Shieber s work on constraints in grammatical formalisms, started in his thesis [68], and continued in his book [69] Another is Mukai s work on the Complex Indeterminate Language CIL. 51] This latter was one of the pioneering computational efforts, and the theory is equally interesting. A theoretical summary can be found in [52] this work is one of a few references I know ....

S. Shieber. Parsing and Type Inference for Natural and Computer languages. PhD thesis, Stanford University, 1989.

....3.4 GIST: PR 2b obtained even in the presence of recursive head categories; when pivots are not lexical items, the pivot corner strategy iteratively applies to all its children. 3.1. 1 The Overall Framework A previous version of the ITG was based on a feature logic very close to that presented in (Shieber, 1989), the latter being an extension and a formalisation of PATR II. This feature logic was used to define a grammatical formalism called X bar Unification Grammar (XBUG) which had nice properties such as: a natural notion of maximality of constituents, which avoided the use of traditional bar ....

.... the TFS formula compiler and to the unifier can be issued that constraint the behaviour of the system in a given way, e.g. by fixing the order in which features are considered upon unification, so as to let the unifier first check frequently failing paths, or by adding restrictors, in the sense of Shieber (1989). The relevant piece of syntax is the following one: 3.6 GIST: PR 2b 4) Directive : Directive directive body ) Directive body : directive spec Directive spec : on feature path try first feature path ....

[Article contains additional citation context not shown here]

Shieber, S.M., (1989), Parsing and Type Inference for Natural and Computer Languages, PhD Thesis, Stanford University and Technical Note 460, SRI.

....FT (sort) extends FT by allowing a partial order on labels [15] Subsumption Constraints. Subsumption is an ordering on the domain of feature algebras. Subsumption constraints have been considered in the context of unification based grammars to model coordination phenomena in natural language [9, 7, 21]. There, one wants to express that two feature structures representing different parts of speech share common properties. For example, the analysis of programming and linguistics in the phrase Feature constraints for [ NP programming] and [ NP linguistics] should share (but might refine ....

S. Shieber. Parsing and Type Inference for Natural and Computer Languages. SRI Internationax [l Technical Note 460, Stanford University, Mar. 1989.

.... and Higher Order Unification Mary Dalrymple Xerox PARC Palo Alto, CA 94304, USA and Center for the Study of Language and Information Stanford University Stuart M. Shieber Division of Applied Sciences Harvard University Cambridge, MA 02138, USA Fernando C. N. Pereira AT T Bell Laboratories Murray Hill, NJ 07974, USA Abstract We present a new method for characterizing the interpretive possibilities generated by elliptical constructions in natural language. ....

Stuart M. Shieber. 1989. Parsing and Type Inference for Natural and Computer Languages.

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S. M. Shieber, Constraint-Based Grammaar Formalisms. Parsing and Type Inference for Natural and Computer Languages. A Bradford Book. Cambridge, Mass.: The MIT Press, 1992.

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S. M. Shieber, Constraint-Based Grammaar Formalisms. Parsing and Type Inference for Natural and Computer Languages. A Bradford Book. Cambridge, Mass.: The MIT Press, 1992.

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