Graph product is a fundamental tool with rich applications in both graph theory and theoretical computer science. It is usually studied in the form f(G∗H) where G and H are graphs, ∗ is a graph product and f is a graph property. For example, if f is the independence number and ∗ is the disjunctive product, then the product is known to be multiplicative: f(G∗H) = f(G)f(H). In this paper, we stud...

An ω-language over a finite alphabet X is a set of infinite sequences of letters of X. Consider congruences IL and Pω, L on X* and a congruence OL on X introduced by an ω-language L. IL, Pω, L, and OL are called the infinitary syntactic-congruence, the principal congruence and the ω-syntactic congruence of L, respectively. If IL (Pω, L, OL) is the equality then L is called an I-disjunctive (P-d...

Abstract This discussion note addresses Caleb Hazelwood’s ‘Practice-Centered Pluralism and a Disjunctive Theory of Art’. Hazelwood advances disjunctive definition art on the basis an analogy with species concept pluralism in philosophy biology. We recognize between art, we applaud attention to practice, are bullish pluralism—but it is mistake take these as for definition.

This paper addresses the makespan minimization in a job-shop environment where the machines are not available during the whole planning horizon. The disjunctive graph model is used to represent the schedules and the concept of blocks is generalized to include the unavailability periods of machines. To solve the problem, we develop a taboo thresholding heuristic that uses a new block-based neigh...

This paper presents a new algorithm that obtains an approximation of the Critical Path in schedules generated using the disjunctive graph model that represents the Job Shop Scheduling Problem (JSSP). This algorithm selects a set of operations in the JSSP, where on the average ninety nine percent of the total operations that belong to the set are part of the critical path. A comparison is made o...

Preferred and Weakly Preferred Answer Sets are extensions to Answer Set Programming (ASP) which allow the user to specify priorities for rules. In this paper we present a first implementation of these formalisms by means of “metainterpreters” on top of DLV, an efficient engine for Disjunctive ASP. This approach shows the suitability of ASP in general and of DLV in particular for fast prototypin...

Train scheduling is a complex and time consuming task of vital importance in many countries. To schedule trains more accurately, efficiently and robustly than permitted by current techniques a novel job shop approach is proposed and implemented. Unique characteristics of train scheduling are firstly incorporated into the disjunctive graph representation of the solution. Constructive algorithms ...

In recent years, much work was devoted to the study of theoretical foundations of Disjunctive Logic Programs and Disjunctive Deductive Databases. While the semantics of non-disjunctive programs is fairly well understood the declarative and computational foundations of disjunctive programming proved to be much more elusive and dif-cult. Recently, two new and very promising semantics have been pr...