A semantics of multiple inheritance.
Proc. of the international symposium on Semantics of data types
GALILEO: a strongly-typed, interactive conceptual language
ACM Transactions on Database Systems (TODS)
Modeling class hierarchies with contradictions
SIGMOD '88 Proceedings of the 1988 ACM SIGMOD international conference on Management of data
Type inference in a database programming language
LFP '88 Proceedings of the 1988 ACM conference on LISP and functional programming
PDM: an object-oriented data model
OODS '86 Proceedings on the 1986 international workshop on Object-oriented database systems
The functional data model and the data languages DAPLEX
ACM Transactions on Database Systems (TODS)
A language facility for designing database-intensive applications
ACM Transactions on Database Systems (TODS)
SIGMOD '83 Proceedings of the 1983 ACM SIGMOD international conference on Management of data
Subtyping in OODB's (extended abstract)
PODS '91 Proceedings of the tenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Containment and minimization of positive conjunctive queries in OODB's
PODS '92 Proceedings of the eleventh ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
PODS '90 Proceedings of the ninth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Supporting Exceptions to Schema Consistency to Ease Schema Evolution in OODBMS
VLDB '94 Proceedings of the 20th International Conference on Very Large Data Bases
Type-safe relaxing of schema consistency rules for flexible modelling in OODBMS
The VLDB Journal — The International Journal on Very Large Data Bases
How knowledge representation meets software engineering (and often databases)
Automated Software Engineering
On the complexity of monotonic inheritance with roles
AAAI'90 Proceedings of the eighth National conference on Artificial intelligence - Volume 1
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Type checking at query compilation time is important for both detecting programmer errors and reducing the running time of queries. We have argued elsewhere [2] that entity-based data management systems which support class hierarchies, such as semantic data models and object-oriented dbms, should not be confined to have “strict inheritance” — i.e., they should permit contradictions between class specifications, albeit in an explicit and controlled way. In this paper we present a type system for queries manipulating objects in such classes. We provide sound and complete axiomatizations of the predications “&sgr; is a subtype of &tgr;” and “expression e has type &tgr;”. The absence of strict inheritance has normally been felt to preclude effective type checking. We show that the problem is co-NP-hard when disjoint types are admitted in the schema, but present a low-order polynomial-time algorithm that determines the absence of type errors in a query when the database has only entities.