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Fast browsing and retrieval of geographically referenced information requires the allocation of data on different storage devices for concurrent retrieval. By dividing the two-dimensional space into tiles, a system can allow users to specify regions of interest using a query rectangle and then retrieving information related to tiles covered by the query. Suppose that there are m I/O devices. A tile...
Semi-structured data are commonly represented by labelled graphs. The labels may be strings, integers, . . . Thus their type is atomic. They are carried by edges and/or nodes. In this paper, we investigate a nested graph representation of semi-structured data. Some nodes of our graphs may be labelled by graphs. Our motivation is to bring the data model in use closer to the natural presentation of...
Based on F-logic, we specify an advanced data model with object-oriented and logic-oriented features that substantially extend the relational approach. For this model we exhibit and study the counterpart to the well-known decomposition of a relation scheme according to a nontrivial nonkey functional dependency. For decomposing a class of a database schema the transformation pivoting is used. Pivoting...
Specification and efficient processing of similarity queries on multimedia databases have recently attracted several research efforts, even if most of them have considered specific aspects, such as indexing, of this new exciting scenario. In this paper we try to remedy this by presenting an integrated algebraic framework which allows many relevant aspects of similarity query processing to be dealt...
Databases with integrity constraints (IC) are considered. For each DB update, i.e. a set of facts to add and of facts to delete, the IC implies its correct expansion: new facts to add and new facts to delete. Simultaneously, each expanded update induces a correct simplification of the IC. In the limit this sequence of expansions and simplifications converges to the maximal correct update expansion...
Suppose that the entries of a relational database are collected in an unreliable way, that is the actual database may differ from the true database in at most one data of each individual. An error-correcting key is such a set of attributes, that the knowledge of the actual data of an individual in this set of attributes uniquely determines the individual. It is showed that if the minimal keys are...
We present a probabilistic data model for complex values. More precisely, we introduce probabilistic complex value relations, which combine the concept of probabilistic relations with the idea of complex values in a uniform framework. We then define an algebra for querying database instances, which comprises the operations of selection, projection, renaming, join, Cartesian product, union, intersection,...
Persistent Turing Machines (PTMs) are multitape machines with a persistent worktape preserved between interactions, whose inputs and outputs are dynamically generated streams of tokens (strings). They are a minimal extension of Turing Machines (TMs) that express interactive behavior. They provide a natural model for sequential interactive computation such as single-user databases and intelligent...
Cardinality constraints as well as key dependencies and functional dependencies are among the most popular classes of constraints in database models. While the formal properties of each of the constraint classes are now well understood, little is known about their interaction. The objective of this paper is to discuss how constraints from these classes go together. We propose methods for reasoning...
Two versions of a set theoretic δ-language are considered as theoretical prototypes for “nested” data base query language where data base states and queries are represented, respectively, as hereditarily-finite (HF) sets and set theoretic operations. It is shown that these versions correspond exactly to (N/D)LOGSPACE computability over HF, respectively. Such languages over sets, capturing also PTIME,...
Non-situation calculus is a way to describe dynamic worlds using first order logic, where a theory is written from the viewpoint of a situation (the propositional fluents hold in that situation). We introduced some functions to allow describing propositional fluents that hold in other situations. We define “progression” as a transformation that changes the situation represented by a non-situation...
An important problem that arises when updating a deductive database is that of integrity constraint maintenance. That is, given a consistent database and an update request, to obtain all possible updates of base facts such that the request is satisfied and no integrity constraint is violated. This problem becomes more complex when view updates are also taken into account. In this paper we define a...
In this investigation we discuss how to improve the quality of decision trees, one of the classification techniques in compensation for small loss of amount of information. To do that, we assume a semantic hierarchy among classes which is ignored in conventional stories. The basic idea comes from relaxing class membership by using the hierarchy and we explore how to preserve the precision of classification...
We introduce the paradigm of High-Level Logic Programming. This paradigm is the consolidation of our recent results on disjunctions, sets, partial-order clauses and aggregation. We show how these concepts are integrated in a natural way into the standard logic programming framework. For this purpose, we present several well known examples from the literature that support this claim. Our approach to...
In this paper we will investigate the novel concept of clausal deductive databases (cd-databases), which are special normal deductive databases — i.e. deductive databases which may contain default negation in rule bodies — over a meta-language $$ \mathcal{L}^{{\text{cd}}} $$ with a fixed set of predicate symbols, namely dis, con, and some built-in predicate symbols. The arguments of the literals...
We present an approach to handle unavailable data sources during query execution over WWW which is based on partial evaluations. Syntax of the set-theoretic query language Δ and some examples of queries are given. We define an ordinary and a lazy semantics for this language. Moreover, we introduce a universe of non-well-founded hereditarily finite protosets and an approximation relation on this universe...
Consider a matrix satisfying the following two properties. There are no two rows of the matrix having the same entries in two cyclically neighbouring columns. On the other hand for each subset of the columns not containing a cyclically neighbouring pair there are two rows having the same entries in these columns. In this paper the magnitude of the minimal number of the rows of such a matrix...
12 We define four different properties of relational databases which are related to the notion of homogeneity in classical Model Theory. The main question for their definition is, for any given database, which is the minimum integer k, such that whenever two k-tuples satisfy the same properties which are expressible in First Order Logic with up to k variables (FOk), then...
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