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111
Transition Network Grammars for Natural Language Analysis
 COMPUTATIONAL LINGUISTICS, D.G. BOBROW, EDITOR
, 1970
"... The use of augmented transition network grammars for the analysis of natural language sentences is described. Structurebuilding actions associated with the arcs of the grammar network allow for the reordering, restructuring, and copying of constituents necessary to produce deepstructure representa ..."
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Cited by 272 (3 self)
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The use of augmented transition network grammars for the analysis of natural language sentences is described. Structurebuilding actions associated with the arcs of the grammar network allow for the reordering, restructuring, and copying of constituents necessary to produce deepstructure representations of the type normally obtained from a transformational analysis, and conditions on the arcs allow for a powerful selectivity which can rule out meaningless analyses and take advantage of semantic information to guide the parsing. The advantages of this model for natural language analysis are discussed in detail and illustrated by examples. An implementation of an experimental parsing system for transition network grammars is briefly described.
Storing semistructured data with STORED
"... Systems for managing and querying semistructureddata sources often store data in proprietary object repositories or in a taggedtext format. We describe a technique that can use relational database management systems to store and manage semistructured data. Our technique relies on a mapping between ..."
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Cited by 233 (8 self)
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Systems for managing and querying semistructureddata sources often store data in proprietary object repositories or in a taggedtext format. We describe a technique that can use relational database management systems to store and manage semistructured data. Our technique relies on a mapping between the semistructured data model and the relational data model, expressed in a query language called STORED. When a semistrcutured data instance is given, a STORED mapping can be generated automatically using datamining techniques. We are interested in applying STORED to XML data, which is an instance of semistructured data. We show how a documenttypedescriptor (DTD), when present, can be exploited to further improve performance.
DTD Inference for Views of XML Data
, 1999
"... We study the inference of Data Type Definitions (DTDs) for views of XML data, using an abstraction that focuses on document content structure. The views are defined by a query language that produces a list of documents selected from one or more input sources. The selection conditions involve vertica ..."
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Cited by 120 (12 self)
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We study the inference of Data Type Definitions (DTDs) for views of XML data, using an abstraction that focuses on document content structure. The views are defined by a query language that produces a list of documents selected from one or more input sources. The selection conditions involve vertical and horizontal navigation, thus querying explicitly the order present in input documents. We point several strong limitations in the descriptive ability of current DTDs and the need for extending them with (i) a subtyping mechanism and (ii) a more powerful specification mechanism than regular languages, such as contextfree languages. With these extensions, we show that one can always infer tight DTDs, that precisely characterize a selection view on sources satisfying given DTDs. We also show important special cases where one can infer a tight DTD without requiring extension (ii). Finally we consider related problems such as verifying conformance of a view definition with a predefined DTD....
Validating Streaming XML Documents
, 2002
"... This paper investigates the online validation of streaming XML documents with respect to a DTD, under memory constraints. We first consider validation using constant memory, formalized by a finitestate automaton (fsa). We examine two flavors of the problem, depending on whether or not the XML doc ..."
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Cited by 78 (2 self)
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This paper investigates the online validation of streaming XML documents with respect to a DTD, under memory constraints. We first consider validation using constant memory, formalized by a finitestate automaton (fsa). We examine two flavors of the problem, depending on whether or not the XML document is assumed to be wellformed. The main results of the paper provide conditions on the DTDs under which validation of either flavor can be done using an fsa. For DTDs that cannot be validated by an fsa, we investigate two alternatives. The first relaxes the constant memory requirement by allowing a stack bounded in the depth of the XML document, while maintaining the deterministic, onepass requirement. The second approach consists in refining the DTD to provide additional information that allows validation by an fsa.
Schemas for Integration and Translation of Structured and SemiStructured Data
 In Proceedings of the International Conference on Database Theory
, 1999
"... Introduction The Web is emerging as a universal data repository, offering access to sources whose data organization varies from strictly structured databases to almost completely unstructured pages, and everything in between. Consequently, much research has recently focused on data integration and ..."
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Cited by 67 (5 self)
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Introduction The Web is emerging as a universal data repository, offering access to sources whose data organization varies from strictly structured databases to almost completely unstructured pages, and everything in between. Consequently, much research has recently focused on data integration and data translation systems [10, 6, 9, 8, 17, 13, 2, 19], whose goals are to allow applications to utilize data from many sources, with possibly widely varying formats. These research efforts have established a common data model of semistructured data, for uniformly representing data from any source. Recently, however, it is being realized that having a common schema model is also beneficial, and even necessary, in translation and integration systems to support tasks such as query formulation, decomposition and optimization, or declarative specification of data translation. As an example, which we use for motivation throughout the paper, recently suggested tools for data translation [2, 11, 19
ContextFree Languages and PushDown Automata
 Handbook of Formal Languages
, 1997
"... Contents 1. Introduction : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 2 1.1 Grammars : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 2 1.2 Examples : : : : : : : : : : : : : : : : : : : : : : : : : : : ..."
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Cited by 61 (0 self)
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Contents 1. Introduction : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 2 1.1 Grammars : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 2 1.2 Examples : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 4 2. Systems of equations : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 5 2.1 Systems : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 6 2.2 Resolution : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 11 2.3 Linear systems : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 12 2.4 Parikh's theorem : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : :
Petri Nets, Commutative ContextFree Grammars, and Basic Parallel Processes
, 1997
"... . The paper provides a structural characterisation of the reachable markings of Petri nets in which every transition has exactly one input place. As a corollary, the reachability problem for this class is proved to be NPcomplete. Further consequences are: the uniform word problem for commutative co ..."
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Cited by 47 (6 self)
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. The paper provides a structural characterisation of the reachable markings of Petri nets in which every transition has exactly one input place. As a corollary, the reachability problem for this class is proved to be NPcomplete. Further consequences are: the uniform word problem for commutative contextfree grammars is NPcomplete; weakbisimilarity is semidecidable for Basic Parallel Processes. Keywords: Petri nets, Commutative Contextfree Grammars, Basic Parallel Processes, Weak bisimilarity. 1. Introduction The reachability problem plays a central role in Petri net theory, and has been studied in numerous papers (see [5] for a comprehensive list of references). In the first part of this paper we study it for the nets in which every transition needs exactly one token to occur. Following [8], we call them communicationfree nets, because no cooperation between places is needed in order to fire a transition; every transition is activated by one single token, and the tokens may flow...
Undecidable Problems for Probabilistic Automata of Fixed Dimension
 Theory of Computing Systems
, 2001
"... We prove that several problems associated to probabilistic finite automata are undecidable for automata whose number of input letters and number of states are fixed. As a corollary of one of our results we prove that the problem of determining if the set of all products of two 47 × 47 matr ..."
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Cited by 32 (3 self)
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We prove that several problems associated to probabilistic finite automata are undecidable for automata whose number of input letters and number of states are fixed. As a corollary of one of our results we prove that the problem of determining if the set of all products of two 47 &times; 47 matrices with nonnegative rational entries is bounded is undecidable.
A formal picture description scheme as a basis for picture processing systems
 Information and Control
, 1969
"... A formal picture description scheme to be used as the basis for picture processing systems is presented, The scheme is applicable to a large class of pictures including, but not restricted to, those containing linelike elements. The paper first presents a general linguistic model for picture proce ..."
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Cited by 26 (0 self)
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A formal picture description scheme to be used as the basis for picture processing systems is presented, The scheme is applicable to a large class of pictures including, but not restricted to, those containing linelike elements. The paper first presents a general linguistic model for picture processing in which the analysis and generation of pictures are defined as the derivation and execution, respectively, of descriptions. A particular realization of the descriptive component of the model including some of its formal properties is then given; a picture class is described in terms of its underlying graph structures by a grammar generating strings in a picture description language. A series of examples illustrate the capability and limitations of the description scheme. Some applications of implemented systems to the analysis and generation of pictures are discussed.
Shuffle on Trajectories: Syntactic Constraints
 Theor. Comp. Sci
, 1998
"... We introduce and investigate new methods to define parallel composition of words and languages. The operation of parallel composition leads to new shufflelike operations defined by syntactic constraints on the usual shuffle operation. The approach is applicable to concurrency, providing a method to ..."
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Cited by 25 (5 self)
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We introduce and investigate new methods to define parallel composition of words and languages. The operation of parallel composition leads to new shufflelike operations defined by syntactic constraints on the usual shuffle operation. The approach is applicable to concurrency, providing a method to define parallel composition of processes. It is also applicable to parallel computation. The operations are introduced using a uniform method based on the notion of trajectory. As a consequence, we obtain a very intuitive geometrical interpretation of the parallel composition operation. These operations lead in a natural way to a large class of semirings. The approach is amazingly flexible, diverse concepts from the theory of concurrency can be introduced and studied in this framework. For instance, we provide examples of applications to fairness property and to parallelization of noncontextfree languages in terms of contextfree and even regular languages. This paper concetrates on syntactic constraints. Semantic constraints will be dealt with in a forthcoming contribution. TUCS Research Group