Recent developments in reification of ER schemata include automatic generation of web-based database administration systems [ERW]. These systems enforce the schema cardinality constraints, but, beyond unsatisfiable schemata, this feature may create unreachable instances. We prove sound and complete characterisations of schemata whose instances satisfy suitable reachability properties; these theorems translate into linear algorithms that can be used to prevent the administrator from reifying schemata with unreachable instances.
Reachability problems in entity-relationship schema instances / S. Vigna - In: Conceptual modeling – ER 2004 : 23rd international conference on conceptual modeling, Shanghai, China, November 8-12, 2004 : proceedings / [a cura di] P. Atzeni [et al]. - Berlin : Springer, 2004. - ISBN 9783540237235. - pp. 96-109 (( Intervento presentato al 23rd. convegno International Conference on Conceptual Modeling tenutosi a Shangai nel 2004 [10.1007/b101693].
Reachability problems in entity-relationship schema instances
S. VignaPrimo
2004
Abstract
Recent developments in reification of ER schemata include automatic generation of web-based database administration systems [ERW]. These systems enforce the schema cardinality constraints, but, beyond unsatisfiable schemata, this feature may create unreachable instances. We prove sound and complete characterisations of schemata whose instances satisfy suitable reachability properties; these theorems translate into linear algorithms that can be used to prevent the administrator from reifying schemata with unreachable instances.
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