One of the key problems when extending relational database query languages to include deductive capabilities, is to provide them with efficient methods for answering recursive queries. During the last few years many algorithms have been proposed to deal with transitive closure computation of a relation. In this paper, we discuss some important criteria for developing transitive closure algorith...

It is given a new algorithm to compute a lower T-transitive approximation of a fuzzy relation that preserves symmetry. Given a reflexive and symmetric fuzzy relation, the new algorithm computes a T-indistinguishability that is contained in the fuzzy relation. It has been developed a C++ program that generates random symmetric fuzzy relations or random symmetric and reflexive fuzzy relations and...

In distributed networks, a target party T could be a person never meet with a source party S, therefore S may not hold any prior evaluation of trustworthiness of T . To get permit to access S, T should be somewhat trusted by S. Consequently, we should study the approach to evaluate trustworthiness of T . To attack the problem, we view individual participant in distributed networks as a node of ...

The set of optimal matchings in the assignment matrix allows to define a reflexive and symmetric binary relation on each side of the market, the equal-partner binary relation. The number of equivalence classes of the transitive closure of the equal-partner binary relation determines the dimension of the core of the assignment game. This result provides an easy procedure to determine the dimensi...

We study the problem of maintaining recursively-de ned views, such as the transitive closure of a relation, in traditional relational languages that do not have recursion mechanisms. In particular, we show that the transitive closure cannot be maintained in relational calculus under deletion of edges. We use new proof techniques to show this result. These proof techniques generalize to other la...

Temporal text understanding and question answering presupposes the availability of a component which computes the transitive closure of a set of statements about interval relations. Vilain and Kautz have addressed the question of computing the transitive closure by translating such statements into equivalent point-based descriptions. The problem is that there are basic statements about interval...

We present a new family of hybrid transitive closure algorithms, and present experimental results showing that these algorithms perform better than existing transitive closure algorithms, includmg matrix-based algorithms that divide a matrix into stripes or into square blocks, and graph-based algmtihms. This family of algorithms can be generalized to solve path problems and to solve problems in...

A partial order on Z obtained by taking the transitive closure of a random relation {i < j and there is an edge ij} is studied. Randomness stems from postulating that an edge ij exists with probability p , independently of all other edges. While studying the random order on the subset [n] , Alon et al. introduced a remarkable notion of a post, defined as an element in Z comparable to all other ...

This paper develops methods to reason about graph transformation rules for proving the preservation of structural properties, especially global properties on reachability. We characterize a graph transformation rule with an applicability condition specifying the matching conditions of the rule on a host graph as well as the properties to be preserved during the transformation. Our previous work...

Two edges are called P 4-adjacent if they belong to the same P 4 (chordless path on 4 vertices). P 4-components, in our terminology, are the equivalence classes of the transitive closure of the P 4-adjacency relation. In this paper, new results on the structure of P 4-components are obtained. On the one hand, these results allow us to improve the complexity of the recognition and orientation al...