Search results for "Decision problem"
showing 10 items of 42 documents
FO^2 with one transitive relation is decidable
2013
We show that the satisfiability problem for the two-variable first-order logic, FO^2, over transitive structures when only one relation is required to be transitive, is decidable. The result is optimal, as FO^2 over structures with two transitive relations, or with one transitive and one equivalence relation, are known to be undecidable, so in fact, our result completes the classification of FO^2-logics over transitive structures with respect to decidability. We show that the satisfiability problem is in 2-NExpTime. Decidability of the finite satisfiability problem remains open.
Comparing normal means: new methods for an old problem
2007
Comparing the means of two normal populations is an old problem in mathematical statistics, but there is still no consensus about its most appropriate solution. In this paper we treat the problem of comparing two normal means as a Bayesian decision problem with only two alternatives: either to accept the hypothesis that the two means are equal, or to conclude that the observed data are, under the assumed model, incompatible with that hypothesis. The combined use of an information-theory based loss function, the intrinsic discrepancy (Bernardo and Rueda 2002}, and an objective prior function, the reference prior \citep{Bernardo 1979; Berger and Bernardo 1992), produces a new solution to this…
Some recent contributions to routing and location problems
2003
CORAL 2003, a Conference on Routing and Location, washeld in Puerto de la Cruz (Tenerife, Spain) from February24–26, 2003. A wonderful place, close to the black sand ofthe beach, and a nice temperature welcomed a group ofsenior and young researchers from Canada, England,France, Germany, and Spain. Social activities were alsoprovided and sponsored by the Cabildo Insular de Tenerife(the local government) and TITSA (the public bus transpor-tation company on the island). The conference corre-sponded to the third annual meeting of a research project,funded by the Spanish Ministry of Science and Technology,developing a Decision Support System for Vehicle Routingand Facility Location Problems (SAD…
On Table Arrangements, Scrabble Freaks, and Jumbled Pattern Matching
2010
Given a string s, the Parikh vector of s, denoted p(s), counts the multiplicity of each character in s. Searching for a match of Parikh vector q (a “jumbled string”) in the text s requires to find a substring t of s with p(t) = q. The corresponding decision problem is to verify whether at least one such match exists. So, for example for the alphabet Σ = {a, b, c}, the string s = abaccbabaaa has Parikh vector p(s) = (6,3,2), and the Parikh vector q = (2,1,1) appears once in s in position (1,4). Like its more precise counterpart, the renown Exact String Matching, Jumbled Pattern Matching has ubiquitous applications, e.g., string matching with a dyslectic word processor, table rearrangements, …
Graph languages defined by systems of forbidden structures: A survey
1988
This paper deals with different ways of defining graph languages. These are the so-called forbidden structures. Some results on decision problems, their complexity, and set theoretic closure properties are scetched. A normal form, the minimal systems, are given. Finally the influence of the different kinds of forbidden structures on the descriptive power of the systems is shown.
A description model for regeneration through urban tourism in rural towns with underused historic real estate
2016
Il presente contributo propone un modello di descrizione (description model) che trova applicazione in una situazione reale di aiuto alla decisione posto dall'urbanista per lo sviluppo turistico delle città rurali nelle zone dell'entroterra siciliano. Il problema decisionale riguarda la città di Cianciana (AG), che negli ultimi anni si è resa protagonista di un particolare fenomeno di turismo internazionale. In particolare, proponiamo un quadro valutativo multicriteriale per la riqualificazione fisica ed economica del centro storico della città attraverso lo sviluppo del turismo. Il modello presentato, relativo a un problema decisionale di tipo descrittivo, è orientato a supportare i deciso…
Visibly pushdown modular games,
2014
Games on recursive game graphs can be used to reason about the control flow of sequential programs with recursion. In games over recursive game graphs, the most natural notion of strategy is the modular strategy, i.e., a strategy that is local to a module and is oblivious to previous module invocations, and thus does not depend on the context of invocation. In this work, we study for the first time modular strategies with respect to winning conditions that can be expressed by a pushdown automaton. We show that such games are undecidable in general, and become decidable for visibly pushdown automata specifications. Our solution relies on a reduction to modular games with finite-state automat…
ALGORITHMS FOR JUMBLED PATTERN MATCHING IN STRINGS
2011
The Parikh vector p(s) of a string s is defined as the vector of multiplicities of the characters. Parikh vector q occurs in s if s has a substring t with p(t)=q. We present two novel algorithms for searching for a query q in a text s. One solves the decision problem over a binary text in constant time, using a linear size index of the text. The second algorithm, for a general finite alphabet, finds all occurrences of a given Parikh vector q and has sub-linear expected time complexity; we present two variants, which both use a linear size index of the text.
Finite automata on timed ω-trees
2003
AbstractIn the last decade Alur and Dill introduced a model of automata on timed ω-sequences which extends the traditional models of finite automata. In this paper, we present a theory of timed ω-trees which extends both the theory of timed ω-sequences and the theory of ω-trees. The main motivation is to introduce a new way of specifying real-time systems and provide tools for studying decidability problems in related fields. We focus on the decision problems and their applications in system verification and synthesis.
Mapping discounted and undiscounted Markov Decision Problems onto Hopfield neural networks
1995
This paper presents a framework for mapping the value-iteration and related successive approximation methods for Markov Decision Problems onto Hopfield neural networks, for both discounted and undiscounted versions of the finite state and action spaces. We analyse the asymptotic behaviour of the control sets and we give some estimates on the convergence rate for the value-iteration scheme. We relate the convergence properties on an energy function which represents the key point in mapping Markov Decision Problems onto Hopfield networks. Finally, an application from queueing systems in communication networks is taken into consideration and the results of computer simulation of Hopfield netwo…