Multi-valued dependencies in the presence of lists

  • Authors:

  • Sven Hartmann;Sebastian Link

  • Affiliations:

  • Massey University, Palmerston North, New Zealand;Massey University, Palmerston North, New Zealand

  • Venue:
  • PODS '04 Proceedings of the twenty-third ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
  • Year:
  • 2004

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Abstract

Multi-valued depdendencies (MVDs) are an important class of relational constraints. We axiomatise MVDs in data models that support nested list types. In order to capture different data models at a time, an abstract approach based on nested attributes is taken. The set of subattributes of some fixed nested attribute carries the structure of a co-Heyting algebra. This enables us to generalise significant features of MVDs from the relational data model to the presence of lists. It is shown that an MVD is satisfied by some instance exactly when this instance can be decomposed without loss of information. The full power of the algebraic framework allows to provide a sound and complete set of inference rules for the finite implication of MVDs in the context of lists. The presence of the list operator calls for a new inference rule which is not required in the relational data model. Further differences become apparant when the minimality of the inference rules is investigated. The extension of the relational theory of MVDs to the presence of lists allows to specify more real-world constraints and increases therefore the number of application domains.