Showing papers on "Graph database published in 1988"

Inference aggregation detection in database management systems

Abstract: The author identifies inference aggregation and cardinality aggregation as two distinct aspects of the aggregation problem. He develops the concept of a semantic relationship graph to describe the relationships between data and then presents inference aggregation as the problem of finding alternative paths between vertices on the graph. He presents an algorithm for processing the semantic relationship graph to discover whether potential inference aggregation problems exist. A method of detecting some aggregation conditions within the database management system (DBMS) is presented that uses the normal DBMS query language and adds additional catalytic data to the DBMS to permit a query to make the inference. The author also suggests the use of set theory to describe aggregation conditions and the addition of set operations to the DBMS to permit the description of aggregation detection queries. >

Theory of database queries

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Formal properties of net-based knowledge representation schemes

Abstract: In the spirit of integrating database and artificial intelligence techniques, a number of concepts widely used in relational database theory are introduced in a knowledge representation scheme. A simple network model, which allows the representation of types, is-a-relationships and disjointness constraints is considered. The concepts of consistency and redundancy are introduced and characterized by means of implication of constraints and systems of inference rules, and by means of graph theoretic concepts.

A new efficient incremental evaluator for attribute grammars allowing conditional semantic equations

Abstract: The evaluator presented performs a depth-first search of the (static) reverse dependency graph associated with a parse tree, interleaved with the execution of semantic rules. The full compound dependency graph is not constructed. Instead, it is implicitly represented by the semantic tree and the dependency graph of the productions. The semantic rules are precompiled as programs written in intermediate code and called semantic modules. Evaluation is a call-by-need evaluation and it is optimal in the number of attribute instances evaluated. >

Intelligent Database Query Translation

Abstract: In this paper we are concerned with techniques for processing database queries that are not required to be formulated based on complete and precise knowledge of the query specification as defined in the database management system In specific, we consider processing queries that are ill-defined, not complete and fuzzy We propose a query translator that tries to bridge the gap between the user's semantically stated query and its full specification as required by the database The translator utilizes a graph based structure to represent queries and relations in the database The translation process involves transforming incomplete query graphs into complete query graphs using attribute covering where the entities of the query are mapped to real entities of the database and functional dependency resolution, where the relational joins between these entities are established The proposed translator is an attempt at incorporating intelligence in query processing systems to support user- friendly features such as cooperative and corrective responses from database systems

A model for the management of imprecise queries in relational databases

Abstract: A new way of using database design theory to facilitate the formulation of precise or imprecise queries in crisp or fuzzy relational databases is proposed. It is shown that a specific representation of multivalued dependencies between attributes in a database can be equivalently translated into the formal framework of qualitative Markov trees. Any imprecise query can then be modelled by a set of belief functions on a set of nodes in the tree to be propagated to some other nodes. The dependency structure can be used to reveal restrictions in the choice of composite attribute values even during formulation of queries.

Algebraic Optimization Of Recursive Database Queries

Abstract: The topic is algebraic optimization of recursive database queries. Queries are expressed by relational algebra expressions including a fixpoint operation. A condition is presented under which a natural join commutes with a fixpoint operation. This condition is a simple check of attribute sets of sub-expressions of the query. The work may be considered a generalization of Aho and Ullman, (1979).The result is interpreted in function free logic database terms as a transformation of the recursively defined predicate involving: (a) elimination of an argument, and (b) propagation of selections (instantiations) to the extensionally defined predicates. A collection of examples shows that this transformation abstracts some optimizations which otherwise are done by more complex graph algorithms (e.g. Bancilhon et al., (1986); Chang, (1985); Gardarin and DeMaindreville, (1986); Henschen and Naqvi, (1984); Kifer and Lozinskii, (1986)). Thus, this optimization is expressed in a form which is not biased towards...

Query Processing on the Entity-Relationship Graph Based Relational Database Systems.

Abstract: An ERG (Entity-Relationship Graph) can be used to provide a semantic structure to a relational database system. An ERG is defined by lo ca l regions. A lo ca l region contains two nodes of entity types and a node of relationship type. The semantic con­ straints of the database represented by the ERG (Entity-Relationship Graph) can be used to enforce the global integrity of the database system. A query is mapped onto the ERG to obtain an ERQG (Entity-Relationship Query Graph). This mapping can be specified by the user by navigating the database or automatically allocated by the sys­ tem via a universal relation interface. The ERQG representation of a query can be semantically decomposed into a sequence of Local Regions. These Local Regins can then be processed according to their order in the query. The ER-semijoin operation is introduced to process this sequence of Local Regions. Using this approach, architec­ tures of database systems are proposed two-phase interface and one-phase interface. An implementation of a user interface is also discussed. LIST OF SYMBOLS AND ABBREVIATIONS txj natural join symbol. division symbol. 7t projection symbol, n intersection, u union. = equality symbol. * not equal symbol. -i negation symbol. —» implication symbol. a "and" symbol, v "or" symbol, c: -contained property,