Modeling Class Hierarchies with Contradictions.

@inproceedings{DBLP:conf/sigmod/Borgida88,
  author    = {Alexander Borgida},
  editor    = {Haran Boral and
               Per-{\AA}ke Larson},
  title     = {Modeling Class Hierarchies with Contradictions},
  booktitle = {Proceedings of the 1988 ACM SIGMOD International Conference on
               Management of Data, Chicago, Illinois, June 1-3, 1988},
  publisher = {ACM Press},
  year      = {1988},
  pages     = {434-443},
  ee        = {http://doi.acm.org/10.1145/50202.50254, db/conf/sigmod/Borgida88.html},
  crossref  = {DBLP:conf/sigmod/88},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}

Abstract

One characteristic feature of object-oriented systems and knowledge bases (semantic data models, conceptual modeling languages, AI frames) is that they offer as a basic paradigm the notion of objects grouped into classes, which are themselves organized in subclass hierarchies. Through ideas such as inheritance and bounded polymorphism, this feature supports the technique of "abstraction by generalization", which has been argued to be of importance in designing Information Systems [11,2].

We provide in this paper examples demonstrating that in some applications over-generalization is likely to occur an occasional natural subclass may contradict in some way one if its superclass definitions, and thus turn out not to be a strict subtype of this superclass. A similar problem arises when an object is allowed to be a member of several classes which make incompatible predictions about its type. We argue that none of the previous approaches suggested to deal with such situations is entirely satisfactory.

A language feature is therefore presented to permit class definitions which contradict aspects of other classes, such as superclasses, in an object-based language. In essence, the approach requires contradictions among class definitions to be explicitly acknowledged. We define a semantics of the resulting language, which restores the condition that subclasses are both subsets and subtypes, and deals correctly with the case when an object can belong to several classes. This is done by separating the notions of "class" and "type", and it allows query compilers to detect type errors as well as eliminate some run-time checks in queries, even in the presence of "contradictory" class definitions.

Copyright © 1988 by the ACM, Inc., used by permission. Permission to make digital or hard copies is granted provided that copies are not made or distributed for profit or direct commercial advantage, and that copies show this notice on the first page or initial screen of a display along with the full citation.

ACM SIGMOD Anthology

CDROM Version: Load the CDROM "Volume 1 Issue 2, SIGMOD '75-'92" and ...

• Windows: Click the letter of your CD drive
  A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
• Mac: Click here
• UNIX/LINUX: mount the CD and click on the path of your mount point:
  /Anthology/smod7592 or /cdrom

• Windows: Click the letter of your CD drive
  A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
• Mac: Click here
• UNIX/LINUX: mount the DVD and click on the path of your mount point:
  /Anthology/aDVD1 or /dvd

Printed Edition

Online Edition: ACM Digital Library

References

[1]

Brian A. Nixon, Lawrence Chung, David Lauzon, Alexander Borgida, John Mylopoulos, Martin Stanley: Implementation of a Compiler for a Semantic Data Model: Experiences with Taxis. SIGMOD Conference 1987: 118-131 BibTeX

[2]

...

[3]

...

[4]

Alexander Borgida: Language Features for Flexible Handling of Exceptions in Information Systems. ACM Trans. Database Syst. 10(4): 565-603(1985) BibTeX

[5]

...

[6]

Peter Buneman, Malcolm P. Atkinson: Inheritance and Persistence in Database Programming Languages. SIGMOD Conference 1986: 4-15 BibTeX

[7]

...

[8]

Luca Cardelli, Peter Wegner: On Understanding Types, Data Abstraction, and Polymorphism. ACM Comput. Surv. 17(4): 471-522(1985) BibTeX

[9]

Arvola Chan, Sy Danberg, Stephen Fox, Wen-Te K. Lin, Anil Nori, Daniel R. Ries: Storage and Access Structures to Support a Semantic Data Model. VLDB 1982: 122-130 BibTeX

[10]

Arvola Chan, Umeshwar Dayal, Stephen Fox, Daniel R. Ries: Supporting a Semantic Data Model in a Distributed Database System. VLDB 1983: 354-363 BibTeX

[11]

John Miles Smith, Diane C. P. Smith: Database Abstractions: Aggregation and Generalization. ACM Trans. Database Syst. 2(2): 105-133(1977) BibTeX

Referenced by

1. Anna Formica, Hans Dietmar Gröger, Michele Missikoff: An Efficient Method for Checking Object-Oriented Database Schema Correctness. ACM Trans. Database Syst. 23(3): 333-369(1998)
2. Eric Amiel, Marie-Jo Bellosta, Eric Dujardin, Eric Simon: Type-safe Relaxing of Schema Consistency Rules for Flexible Modeling in OODBMS. VLDB J. 5(2): 133-155(1996)
3. H. V. Jagadish: The INCINERATE Data Model. ACM Trans. Database Syst. 20(1): 71-110(1995)
4. Eric Amiel, Marie-Jo Bellosta, Eric Dujardin, Eric Simon: Supporting Exceptions to Schema Consistency to Ease Schema Evolution in OODBMS. VLDB 1994: 108-119
5. Nick Bassiliades, Ioannis P. Vlahavas: Modelling Constraints with Exceptions in Object-Oriented Databases. ER 1994: 189-204
6. Michael Dobrovnik, Johann Eder: Adding View Support to ODMG-93 (Invited Paper). ADBIS 1994: 62-73
7. H. V. Jagadish: Incorporating Hierarchy in a Relational Model of Data. SIGMOD Conference 1989: 78-87
8. Yannis E. Ioannidis, Timos K. Sellis: Conflict Resolution of Rules Assigning Values to Virtual Attributes. SIGMOD Conference 1989: 205-214
9. Alexander Borgida: Type Systems for Querying Class Hierarchies with Non-strict Inheritance. PODS 1989: 394-400