S. Spaccapietra, C. Parent, K. Ytongnon, M.S. Abaidi: "Generalizations and the Entity-Relationship Approach", Proc. 3rd International Symposium on Computer and Information Sciences, Izmir, Turkey, October 29-November 2, 1988  Home/Search   Document Not in Database   Summary   Related Articles

....multivalued attribute (maximum cardinality 1) form a bag; the population of an entity type (relationship type) may include different occurrences with the same value. 4 An extended version, ERC , also supports two generalization relationships: the is a and the may be a relationships [Spaccapietra 88] The former corresponds to the well known generalization concept; the latter has the same semantics, but does not require an inclusion dependency between the sub type and the super type. No automatic inheritance is implicitly built in the querying mechanism, but an explicit operator provides for ....

....the ERC calculus and the ERC algebra has been demonstrated [Rolin 89] Although this achieves our basic objectives, further work remains to be done in this area. First, we need to extend the ERC calculus to support the generalization constructs which have been recently added to the ERC model [Spaccapietra 88] Next, we intend to benefit from the formal identification of the gap between the general and the restricted calculus, to investigate what restructuring operators could be acceptable to define another algebraic language (possibly a superset of 18 the actual algebra) to express (instead of ....

S. Spaccapietra, C. Parent, K. Ytongnon, M.S. Abaidi: "Generalizations and the Entity-Relationship Approach", Proc. 3rd International Symposium on Computer and Information Sciences, Izmir, Turkey, October 29-November 2, 1988

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