G.M. Kuper. The Logical Data Model: A New Approach to Database Logic. PhD thesis, Stanford University, 1985. 2O  Home/Search   Document Not in Database   Summary   Related Articles   Check

....schemes could be built from the same server. The model is not aimed at representing all HTML features, but only those that we found relevant in modeling repeated patterns and interrelated pages. The model has a lot of similarities with complex object models with object identifiers (OIDs) [7, 27], with some differences and restrictions. Let us comment on two aspects. First, it is clear that URLs play here a role that is similar to that of OIDs in complex object models. However, there is one difference: OIDs are completely transparent, whereas URLs are visible and, although in most cases ....

G.M. Kuper. The Logical Data Model: A New Approach to Database Logic. PhD thesis, Stanford University, 1985. 2O

....two different results of the query applied to a database are isomorphic through an isomorphism that 1 The work of Abiteboul and Vianu was not restricted to queries only, but also included updates. In this paper we will focus on the query aspect. 2 Determinacy was also implicit in Kuper s thesis [21]. 2 is the identity on the domain of the input database. Hence, the isomorphism can only permute the new objects. Determinacy thus intends to isolate the very weak form of non determinism which is needed to accommodate new objects. It turned out that IQL is not complete for the determinate ....

G. Kuper. The Logical Data Model: A New Approach to Database Logic. PhD thesis, Stanford University, 1985.

....however simpler than IQL, because it manipulates only objects, it never makes explicit reference to oids, and it does not manipulate relations. It is also more powerful because it can express duplicate elimination, manipulate lists, handle inheritance trees. IQL is more powerful than languages in [5, 14]. User level query laguages such as EXCESS [8] and [2] are can be seen as sublanguages of OQL. Shaw and Zdonik [19] and Vadenberg and DeWitt [21] provide object algebra for object oriented databases. But neither of them attempt to manipulate mixture of sets and lists. A few other languages ....

G. M. Kuper. The logical data model: A new approach to database logic. PhD Thesis, Stanford University, 1985.

.... several of the constructs of AQUA (including grouping and immutable semantics) EXTRA EXCESS also attempts to support a large number of bulk types, but does not explicitly provide sets (they are provided only by eliminating duplicates from multisets) The inclusion of a union type is not new (see [17]) but we provide it with a clean algebraic interface using both tagcase and typecase constructs to be fully general. The impor2 tance of being flexible about the addition of new bulk types has been established (see [19] the modularity of the AQUA approach facilitates this to an extent by ....

G. M. Kuper. The Logical Data Model: A New Approach to Database Logic. Ph.D. thesis, Dept. of Computer Science, Stanford University,, Stanford, CA, Sept 1985.

....different schemes could be built from the same server. The model is not aimed at representing all HTML features, but only those that we found relevant in modeling repeated patterns and interrelated pages. The model has a lot of similarities with complex object models with object identifiers (OIDs) [7, 27], with some differences and restrictions. Let us comment on two aspects. First, it is clear that URLs play here a role that is similar to that of OIDs in complex object models. However, there is one difference: OIDs are completely transparent, whereas URLs are visible and, although in most cases ....

G.M. Kuper. The Logical Data Model: A New Approach to Database Logic. PhD thesis, Stanford University, 1985.

....issues. These features make algebraic specification desirable for a data model retrieval language. In recent years it has become apparent that the relational model is not always the right choice for a particular application [Kent79, Care88a, Schw86] and many new data models have been proposed [Abit88b, Lecl87, Fish87, Maie86c, Bane87, Mano86, Roth88, Sche86, Kupe85, Abit88a]. Thus an important open question is this: Exactly how far can the algebraic approach be taken Is it a reasonable way to implement and optimize all data models, or is there some level of complexity of the data model at which the approach is no longer justified This thesis will extend the ....

....and assume that salary is functionally dependent on name. To put these department names into a set valued attribute, we would use the P operator as follows: P Dept (Emp) For each (Name, Salary) pair we will now have a set of Dept attributes. 2.3.3. The LDM Algebra The Logical Data Model (LDM [Kupe85]) is an extended complex object model which uses surrogates to refer to every object in the database (and in that sense it is an object oriented model everything is an object) Objects are built recursively from scalars, sets, tuples, and the union type constructor. Every object in a set, tuple ....

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G. M. Kuper, "The Logical Data Model: A New Approach to Database Logic," PhD. Thesis, Dept. of Computer Science, Stanford University, Stanford, CA, Sept. 1985.

....problem. Another issue that is more important with an object oriented model is the object invention [HS89] which is needed because some deduced information must be represented with new objects (Section 2) Many other propositions have been made in the field of logic for objects, such as LDM [Ku85], O Logic [Mai86] or COL [AG87] Here the emphasis is put on tractability, rather than expressiveness. Some operations, like negation, which would have lead to languages with no obvious efficient implementation strategies, have not been incorporated. As it stands, the LAURE logic is a subset of ....

....restrictions is the existence of an efficient strategy for top down resolution. A more detailed comparison with other logics for objects is given in Section 8. A Relational algebra has been developed, whose expressive power is equivalent to the logic language L 3 (Section 5) Like the LDM algebra [Ku85], this algebra is designed for efficient implementation and compilation of queries. It supports a formal operation, called differentiation, which allows positive updates to be performed efficiently by concentrating only on the part of a rule that changes when the update is performed. The idea is ....

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G. M. Kuper: "The Logical Data Model: A New Approach to Database Logic," PhD Dissertation, Stanford University, 1985.

....our logical language, global constraints are necessary to introduce disjunctive information in the object oriented database [IVN90] We then investigate the necessary relationship between constraints and rules. A more complete description of the LAURE data model (and a comparison with similar work [Ku85] [AK89] KW89] may be found in [Ca91a] 2.1 Object Oriented Deduction In this paper we assume the existence of an object domain O with a taxonomy (a lattice S of classes) a type system and some features (instance variables or methods) to which we attach binary relations [Ca91a] The object ....

....produces a sequence of computations that can be executed without any special data structure, whereas the RETE algorithm requires a complex graph structure to be maintained. This work shares many similarities with many theoretical approaches to merging object oriented and logic programming [Ku85] [AK89] AKP90] The closest example is the revisited O logic [KW89] which is also intended as a framework for AI programming. The LAURE model is a strict subset of this more ambitious model but is able to propose realistic implementation techniques from these restrictions [Ca91a] In addition, ....

G. M. Kuper. The Logical Data Model: A New Approach to Database Logic. PhD Dissertation, Stanford University, 1985.

....queries. 2 A non deterministic query is called determinate if any two different results of 1 The work of Abiteboul and Vianu was not restricted to queries only, but also included updates. In this paper we will focus on the query aspect. 2 Determinacy was also implicit in Kuper s thesis [21]. the query applied to a database are isomorphic through an isomorphism that is the identity on the domain of the input database. Hence, the isomorphism can only permute the new objects. Determinacy thus intends to isolate the very weak form of non determinism which is needed to accommodate new ....

G. Kuper. The Logical Data Model: A New Approach to Database Logic. PhD thesis, Stanford University, 1985.

.... not always have [SS77,Co79] This has motivated a great deal of research during the past decade on structured data models: the so called semantic data models (cf. AH87, HM81, Sh81] nested relations (cf. FT83,JS82] and complex objects (cf. BK86] Continuing in this spirit, we introduced in [KV84,Ku85] the Logical Data Model (LDM) which combines and extends Jacobs database logic [Ja82] and Hull and Yap s format model [HY82] This model uses three basic operations to structure data: product, union, and power set. 1 These operations can be combined not only hierarchically but also in a ....

....j ) for 1 j n, 3. if v is a union node with successors v 1 ; v n , then data(l) has to be a member of [ n j=1 I(v j ) and 4. if v is a power node with successor w, then data(l) has to be a subset of I(w) For more formal definitions and several examples the reader is referred to [KV84,Ku85]. 2.2 LDM Logic Let S be a schema. We define a many sorted logic L(S) over S. Each variable in L(S) has a sort, where the sorts are the nodes of S. The sorts restrict the possible values that the variables can take. For example, if x is a variable of type v, then x can assume values only from ....

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Kuper, G.M.: The logical data model: a new approach to database logic. Ph.D. Dissertation, Stanford University, 1985. 24

....to this problem is to restrict the queries to ones not that do not contain cycles, while allowing cyclicity in the database. Furthermore, we allow the query to refer explicitly to names only in nodes of the database. For a more detailed discussion of the motivation underlying our approach see [Kup85]. More recent work, e.g. IQL ( has shown how query languages could be defined to allow cyclic queries. 5.1. The Query Language Definition 15: Let S = hV; E; i be an LDM schema. A query on S consists of a tuple Q = hSQ ; Phi Q ; OE Q i where 1. SQ is an extension of S. 2. OE Q is a ....

....Fig. 8. Example 11: OE u 0 (x u 0 ) is (9y u ) x u 0 = v y u ) x u 0 = v Absalom ) This query is safe since the set of candidate data values is R = f Jesse, David, Batsheba, Solomon, Rehoboam, Absalomg. Testing safety of relational queries can be reduced to testing safety of LDM queries [Kup85]. As a consequence, testing for safety is, in general, undecidable. It is decidable, however, to test whether a given query Q on a schema S is safe on a given instance I. We now describe the decision procedure. Lemma 12: Let w 1 ; w n be all of the nodes of the database schema S that are ....

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G. M. Kuper. The Logical Data Model: A New Approach to Database Logic. PhD thesis, Stanford University, 1985.

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G.M. Kuper. The Logical Data Model: A New Approach to Database Logic. PhD thesis, Stanford University, 1985.

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