id: 01935908
dt: j
an: 01935908
au: Tari, Zahir; Stokes, John; Spaccapietra, Stefano
ti: Object normal forms and dependency constraints for object-oriented
    schemata.
so: ACM Trans. Database Syst. 22, No. 4, 513-569 (1997).
py: 1997
pu: ACM Press, New York, NY
la: EN
cc: H.2.1 H.2.4
ut: design; theory
ci: 
li: doi:10.1145/278245.278247
ab: Summary: \BeginparWe address the development of a normalization theory for
    object-oriented data models that have common features to support
    objects. We first provide an extension of functional dependencies to
    cope with the richer semantics of relationships between objects, called
    {\it path dependency, local dependency,} and {\it global dependency}
    constraints. Using these dependency constraints, we provide normal
    forms for object-oriented data models based on the notions of {\it user
    interpretation} (user-specified dependency constraints) and {\it object
    model}. In constrast to conventional data models in which a normalized
    object has a unique interpretation, in object-oriented data models, an
    object may have many multiple interpretations that form the model for
    that object. An object will then be in a normal form if and only if the
    user{’}s interpretation is derivable from the model of the object.
    Our normalization process is by nature iiterative, in which objects are
    restructured until their models reflect the user{’}s
    interpretation.\Endpar (Provider: ACM) Review: \BeginparAlthough
    relational design theory is nearly as old as the relational model
    itself, it has been extended in different directions. One is
    non{‒}first normal form data models, especially nested normal form.
    Another is mappings from the entity-relationship model to the
    relational model. The authors suggest and investigate a normalization
    approach to object-oriented database schemas.\Endpar \BeginparMany
    proponents of object-oriented data models find them better able to
    support modeling mechanisms such as inheritance, complex objects, and
    object identity than the classical relational model. Tari et al.\space
    feel that the traditional design and normalization theory and
    techniques of the relational model are similarly inadequate for the
    object-oriented model. They therefore propose an object-oriented
    normalization that considers, instead of implementation issues such as
    redundancy and update problems, consistency between what they call the
    user interpretation of the universe of discourse and the object
    interpretation.\Endpar \BeginparThe authors begin with the definition
    and representation of the object-oriented data model, together with an
    example that they use throughout the paper. Next, they define a path,
    which is a sequence of related objects in the schema, and the
    projection algebra, which supports navigation within the schema. These
    concepts form the basis for the different constraints for the model:
    path dependency constraints, local dependency constraints, global
    dependency constraints, and key constraints. These constraints satisfy
    sets of inference axioms, similar to the functional and multivalued
    dependencies of the relational model. The authors present the formal
    definitions of an object{’}s interpretation and model and of object
    normal form. A set of normalization rules is discussed and shown to be
    complete. Finally, to complete the analogy to other flavors of data
    model normalization, the authors produce and analyze algorithms for
    transforming an object-oriented schema into a normalized one.\Endpar
    \BeginparAs the object-oriented data model matures, it is important to
    establish standards and axioms of the nature enjoyed by its
    predecessors. This paper is useful and interesting in this context; it
    is primarily for scholars, but will interest practitioners as well.
    Readers should be aware, however, that despite the similarity of
    language, the forms discussed here are not extensions of relational
    normalization. Although the style is that of abstract reasoning, with
    theorems and proofs, the authors include a rich set of illustrative
    examples.\Endpar (Provider: ACM)
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