S. Grumbach and T. Milo. An Algebra for POMSETS. In Proc. Intern. Conf. Database Theory, 1995.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....an event and assigns a domain dependent symbol to it. The event symbols together with their attributes are then inserted into the database. Example systems for symbolic processing in activity recognition are provided in [1] The use of partial orders to model concurrency is studied in [7] while [2, 6] are examples of the design of partially ordered databases. The main di#erence between our data model and that of others is in fixing of the temporal relation between eventss and identification of a specific class of partial orders, namely semiorders. With appropriate semantic constraint in the ....

S. Grumbach and T. Milo. An algebra for pomsets. In ICDT '95, pages 191--207. Springer-Verlag, 1995.

....between the computer vision algorithms and the database component, that is, essentially with a data modeling issue. The actual database structure goes beyond its scope. There is a rich literature in the theory of temporal databases, including the management of simultaneity and uncertainty [6, 9, 8]. Our database model has been described in [7, 10] 2 Overview The goal of the Presence technology is to collect events from an environment, store them, and allow users to search and view them, either live (i.e. while the actual events are happening) or from an archive of stored events. The ....

Stephane Grumbach and Tova Milo. An algebra for pomsets. In Proceedings, Database Theory - ICDT '95, Prague, Czech Republic, 11-13 Jan., pages 191--207. SpringerVerlag, 1995.

....solution. However, in other cases, such as genome databases and text databases, there is still a need for more flexibility in data representation and manipulation. The problem of extending relational databases with string manipulation features has recently motivated several research proposals [4, 8, 5, 6, 7]. In fact, sequences represent a particularly interesting domain for query languages. In contrast to sets, computations over sequences can easily become infinite, even when the underlying alphabet is finite. This is because repetitions of symbols are allowed, so that the number of possible ....

S. Grumbach and T. Milo. An algebra for POMSETS. In Fifth International Conference on Data Base Theory, (ICDT'95), Prague, Lecture Notes in Computer Science, Springer-Verlag, pages 191-- 207, 1995.

....in the elementary functions [23] The semantics, the finiteness property and the expressive power represent the main contributions of this paper. 1 INTRODUCTION 5 1. 1 Background Sequence query languages have been recently investigated in the context of functional and algebraic programming [10, 18], and some sophisticated and expressive languages have been proposed. Great care has been devoted to the development of tractable languages, that is, languages whose complexity is in ptime. In [10] for example, a functional query language for nested lists is obtained by introducing a new form of ....

....list is used to control the number of iterative steps, while the other list can be modified at each iteration. This mechanism ensures that query answers are finite. The language is then restricted to express exactly the class of ptime mappings over nested lists. A similar result is reported in [18], in which an algebra for partially ordered multi sets (pom sets) is defined. The algebra is obtained by extending the bag algebra of [17] with new operators to handle arbitrary pomsets, plus an iterator for performing structural recursion [8] The authors define a tractable fragment of the ....

[Article contains additional citation context not shown here]

S. Grumbach and T. Milo. An algebra for POMSETS. In Fifth International Conference on Data Base Theory, (ICDT'95), Prague, Lecture Notes in Computer Science, pages 191--207, 1995.

....we decode the output document in the usual way (see proof of Theorem 1) It is easy to see that the resulting program is safe and correctly computes the machine output. Pi The result is interesting since it provides a characterization of the complexity of Editor programs based on ptime. See [10, 19, 25, 34] for other ptime expressibility results. Note that, although Editor programs can be considered as a string counterpart of loop programs [38, 26] their complexity is considerably different. Loop programs are a formalism for computing on integers; they work on integer variables, and are based on ....

S. Grumbach and T. Milo. An algebra for POMSETS. In Fifth International Conference on Data Base Theory, (ICDT'95), Prague, Lecture Notes in Computer Science, pages 191--207, 1995.

....Theorem 4 (ptime Expressibility) The class of safe simple Editor programs expresses exactly ptime, that is, the class of document restructurings computable in polynomial time. The result is interesting since it provides a characterization of the complexity of Editor programs based on ptime. See [10, 18, 24, 32] for other ptime expressibility results. Note that, although Editor programs can be considered as a string counterpart of loop programs [36, 25] their complexity is considerably different. Loop programs are a formalism for computing on integers; they work on integer variables, and are based on ....

S. Grumbach and T. Milo. An algebra for POMSETS. In Fifth International Conference on Data Base Theory, (ICDT'95), Prague, Lecture Notes in Computer Science, pages 191--207, 1995.

....in this space to measure similarity. Retrieval by similarity has also been studied in the context of image retrieval [14] genome protein matching [3, 11] and text string searching [28] Other authors have recently studied models and languages for databases containing sequences, e.g. 5] [12], 9] 19] 23] but without taking into account notions of similarity or approximation. In a previous paper [15] Jagadish et al. developed a general framework for posing queries based on similarity. The framework enables a formal definition of the notion of similarity for an application domain ....

S. Grumbach and T. Milo. An algebra for pomsets. Proc. of ICDT, 1995.

....an event and assigns a domain dependent symbol to it. The event symbols together with their attributes are then inserted into the database. Example systems for symbolic processing in activity recognition are provided in [1] The use of partial orders to model concurrency is studied in [7] while [2, 6] are examples of the design of partially ordered databases. The main difference between our data model and that of others is in fixing of the temporal relation between eventss and identification of a specific class of partial orders, namely semiorders. With appropriate semantic constraint in the ....

S. Grumbach and T. Milo. An algebra for pomsets. In ICDT '95, pages 191--207. Springer-Verlag, 1995.

....before computing the Euclidean distance. Retrieval by similarity has also been studied in the context of image retrieval [15] genome protein matching [3, 12] and text string searching [31] Other authors have recently studied models and languages for databases containing sequences, e.g. 5] [13], 10] 22] 26] but without taking into account notions of similarity or approximation. In a previous paper [16] Jagadish et al. developed a general framework for posing queries based on similarity. The framework enables a formal definition of the notion of similarity for an application ....

S. Grumbach and T. Milo. An algebra for pomsets. Proc. of ICDT, 1995.

....4 provides preliminary definitions. finally, Section 5, develops the formal semantics of the language. 2 Background In recent years, several query languages for sequence databases have been proposed in the literature. On one hand, there are languages based on functional and algebraic programming [13, 18]. In this context, some sophisticated and expressive languages have been proposed, and great care has been devoted to the development of tractable languages, that is, languages whose complexity is in ptime. On the other hand, there are languages based on predicate logic [24, 15, 17] In this ....

S. Grumbach and T. Milo. An algebra for POMSETS. In Fifth International Conference on Data Base Theory, (ICDT'95), Prague, Lecture Notes in Computer Science, pages 191--207, 1995.

....of the restricted language. Appendix B establishes results on a class of guarded programs, results used in a number of expressibility proofs in the paper. 1. 1 Background Sequence query languages have been recently investigated in the context of functional and algebraic programming [14, 22], and some sophisticated and expressive languages have been proposed. Great care has been devoted to the development of tractable languages, that is, languages whose complexity is in ptime. In [14] for example, a functional query language for nested lists is obtained by introducing a new form of ....

....One list is used to control the number of iterative steps, while the other list can be modified at each iteration. This mechanism ensures that query answers are finite. The language is then restricted to express exactly the class of ptime mappings over nested lists. A similar result is reported in [22], in which an algebra for partially ordered multi sets (pom sets) is defined. The algebra is obtained by extending the bag algebra of [21] with new operators to handle arbitrary pomsets, plus an iterator for performing structural recursion [11] The authors define a tractable fragment of the ....

[Article contains additional citation context not shown here]

S. Grumbach and T. Milo. An algebra for POMSETS. In Fifth International Conference on Data Base Theory, (ICDT'95), Prague, Lecture Notes in Computer Science, pages 191--207, 1995.

....this paper, we characterize the expressive power of subsets of Sequence Datalog in terms of sequence functions. We prove expressibility results for both the class of ptime sequence functions and the class of elementary sequence functions [23] ptime expressibility results were first reported in [10, 15] with respect to listbased databases of complex objects. Here, we extend those results to any hyper exponential time function. In [17] expressibility results for intermediate types were proved in terms of hyper exponential time. We extend these results to sequences. In [22] we extend our ....

....following result. Theorem 5 Acyclic transducer networks of order 2 express exactly the class of sequence functions computable in ptime. This theorem provides a characterization of ptime in terms of transducer networks. Other ptime characterizations have been presented in the literature (e:g: [10, 6, 15]) but transducer networks admit a fine grained characterization in terms of network diameter [21] When the order of transducer networks increases from 2 to 3, the complexity of the resulting sequence functions increases dramatically, as the following theorem shows. Theorem 6 Acyclic transducer ....

S. Grumbach and T. Milo. An algebra for POMSETS. In ICDT, 1995.

....machine. Relational complexity applies as well very naturally to queries on bag databases, since they are generic mappings. We haven t investigated this issue in the present paper. Nevertheless, an extension of the relational machines with counters was proposed in [GO93] and it was shown in [GM95], that there are close relationships between bags and counters. 3 An Algebra for Bags In the following we present an algebra for bag manipulation. This algebra extends the complex object algebra [AB87] in the spirit of the bag algebras presented in [DGK82, Alb91] We start by presenting the ....

....the expressive power is increased, and practical queries (such as cardinality comparison) which were not definable with set semantics, become definable with the bag semantics. The bags essentially give the ability to count. Usage of other data types give rise to new definable queries as shown in [GM95]. Nest vs. powerset In this paper, we considered very powerful primitives to deal with nested bags, such as the powerset. Weaker primitives were proposed in the case of nested sets, such as the set nesting operator, nest. It was shown in [PG88, PG92] that, in the nested relation algebra with no ....

S. Grumbach and T. Milo. An algebra for pomsets. In G. Gottlob and M. Vardi, editors, Proc. Int. Conf. on Database Theory, pages 191--207, Prague, 1995. Springer Verlag. LNCS 893.

....the Euclidean distance in these spaces to measure similarity. Other domain specific work on approximate string searching in text, images, and biochemical data includes [AFS93, AGMML90, GCB92, J91] Other authors have recently studied models and languages for databases containing sequences, e.g. [CRSV94, GM95, GNU94, GW92, Ric92, SLR94]) but without taking into account notions of similarity or approximation. In this paper we generalize this type of work in two directions. First, we develop a domain independent framework for defining notions of similarity. Second, we go beyond specific questions such as find all objects ....

S. Grumbach and T. Milo. An algebra for pomsets. In Proc. Int. Conf. on Database Theory, Springer Verlag, pages 191-207, Prague, 1995.

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S. Grumbach and T. Milo. An Algebra for POMSETS. In Proc. Intern. Conf. Database Theory, 1995.

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S. Grumbach and T. Milo. An algebra for POMSETS. In Fifth International Conference on Data Base Theory, (ICDT'95), Prague, Lecture Notes in Computer Science, SpringerVerlag, pages 191--207, 1995. 27

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S. Grumbach and T. Milo, "An algebra for pomsets," in ICDT '95, pp. 191--207, Springer-Verlag, 1995.

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S. Grumbach and T. Milo. An algebra for POMSETS. In Fifth International Conference on Data Base Theory, (ICDT'95), Prague, Lecture Notes in Computer Science, pages 191--207, 1995.

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S. Grumbach and T. Milo. An algebra for POMSETS. In ICDT, 1995.

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