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The behaviour of automata in lybrinths is a rather new field of automata theory, but more than one hundred papers devoted to this topic have been published. In this paper, we consider the key notions, problems, achievements, methods to solve problems related to an important direction of this field, the behaviour of collectives of automata in labyrinths. In a series of cases, we give base assertions in a more strong form and give a more general presentation that the authors of the corresponding papers do. New results are also contained in this survey. [ABSTRACT FROM AUTHOR]

No abstract received. [ABSTRACT FROM AUTHOR]

In this paper we consider the transformation from (minimal) non-deterministic finite automata (NFAs) to deterministic finite cover automata (DFCAs). We want to compare the two equivalent accepting devices with respect to their number of states; this becomes in fact a comparison between the expression power of the nondeterministic device and the expression power of the deterministic with loops device. We prove a lower bound for the maximum state complexity of deterministic finite cover automata obtained from non-deterministic finite automata of a given state complexity n, considering the case of a binary alphabet. We show, for such binary alphabets, that the difference between maximum blow-up state complexity of DFA and DFCA can be as small as 2⌈n/2;⌉-2 compared to the number of states of the minimal DFA. Moreover, we show the structure of automata for worst case exponential blow-up complexity from NFA to DFCA. We conjecture that the lower bound given in the paper is also the upper bound. Several results clarifying some of the structure of the automata in the worst case are given (we strongly believe they will be pivotal in the upper bound proof). [ABSTRACT FROM AUTHOR]

As to learning effect, it may be more appropriate to assume that position-based learning takes place during machine setups only, while sum-of-processing-time-based learning occurs in considering the experience that workers have gained from producing jobs. Thus, in this paper, we consider sum-of-processing-time-based learning on job processing time and position-based learning on setup time in single-machine group scheduling problems. The objectives are to minimize the makespan and the total completion time, respectively. We provide two polynomial time algorithms to solve the makespan minimization problems. On the other hand, we also provide two polynomial time algorithms to solve the total completion time minimization problems under certain conditions. [ABSTRACT FROM AUTHOR]

Extended Finite Automata (EFA), i.e., finite automata extended with variables, are a suitable modeling framework for discrete event systems owing to their compactness, resulting from the use of variables. In this paper, we propose a symbolic algorithm that efficiently synthesizes a supervisor for a plant modeled by an EFA and a specification defined by another EFA. The principle of the algorithm is to iteratively strengthen the guards of the plant EFA so that forbidden or blocking states become unreachable in the controlled plant. As a consequence of the algorithm, the controlled behavior is modeled by an EFA having the same structure as the plant EFA, having stronger guards and is shown to be maximally permissive. We illustrate our algorithm via a simple manufacturing example. [ABSTRACT FROM PUBLISHER]

Machine learning algorithms frequently suffer from the insufficiency of training data and the usage of inappropriate distance metric. In this paper, we propose a joint learning of labels and distance metric (JLLDM) approach, which is able to simultaneously address the two difficulties. In comparison with the existing semi-supervised learning and distance metric learning methods that focus only on label prediction or distance metric construction, the JLLDM algorithm optimizes the labels of unlabeled samples and a Mahalanobis distance metric in a unified scheme. The advantage of JLLDM is multifold: 1) the problem of training data insufficiency can be tackled; 2) a good distance metric can be constructed with only very few training samples; and 3) no radius parameter is needed since the algorithm automatically determines the scale of the metric. Extensive experiments are conducted to compare the JLLDM approach with different semi-supervised learning and distance metric learning methods, and empirical results demonstrate its effectiveness. [ABSTRACT FROM AUTHOR]

Over the past few years, there has been a renewed interest in the consensus clustering problem. Several new methods have been proposed for finding a consensus partition for a set of 11 data objects that optimally summarizes an ensemble. In this paper, we propose new consensus clustering algorithms with linear computational complexity in n. We consider clusterings generated with a random number of clusters, which we describe by categorical random variables. We introduce the idea of cumulative voting as a solution for the problem of cluster label alignment, where unlike the common one-to-one voting scheme, a probabilistic mapping is computed. We seek a first summary of the ensemble that minimizes the average squared distance between the mapped partitions and the optimal representation of the ensemble, where the selection criterion of the reference clustering is defined based on maximizing the information content as measured by the entropy. We describe cumulative vote weighting schemes and corresponding algorithms to compute an empirical probability distribution summarizing the ensemble. Given the arbitrary number of clusters of the input partitions, we formulate the problem of extracting the optimal consensus as that of finding a compressed summary of the estimated distribution that preserves the maximum relevant information. An efficient solution is obtained using an agglomerative algorithm that minimizes the average generalized Jensen-Shannon divergence within the cluster. The empirical study demonstrates significant gains in accuracy and superior performance compared to several recent consensus clustering algorithms. [ABSTRACT FROM AUTHOR]

Takagi Sugeno Fuzzy models have been successfully applied to a number of scientific and engineering problems during recent years. A lot of investigations have been done to modify systematic design of Takagi Sugeno fuzzy model. Besides the other, FLEXFIS algorithm is widely used to improve the learning process of Takagi Sugeno model. However, the performance of FLEXFIS algorithm lacks when using the microarray gene expression data i.e. there may be a chance of identifying same data item in two clusters. This will produce the conflict while taking decision about the availability of the data set present in the particular cluster (rule). So to avoid such drawbacks in the existing FLEXFIS algorithm a new technique is proposed in this paper. The proposed method comprises of two stages viz., FLEXFIS with overlapping clustering approach and conflict analysis. The Takagi Sugeno Fuzzy model uses the improved version of FLEXFIS with overlapping clustering approach to cluster the incoming data into the respective clusters. The conflict analysis is performed on the resulting clustered data from the previous stage. The identification and analysis of the data which are present in more than one cluster based on similarities in the behavior is considered. The partitioning of the data into a particular cluster or rule base in a defined manner is carried out in the conflict analysis phase. The implementation result shows the effectiveness of proposed conflict analysis technique in clustering the data in a defined cluster. The performance of the proposed conflict analysis technique is evaluated by conducting different experiments on different microarray gene expression datasets. Moreover, the performance of the proposed technique is compared with the existing FLEXFIS algorithm. The comparison result shows that the proposed technique more accurately clusters the gene data into their corresponding cluster or rule than the existing approach. [ABSTRACT FROM AUTHOR]

Weighted timed automata (WTA), introduced in Alur et al. (Proceedings of HSCC'01, LNCS, vol. 2034, pp. 49-62, Springer, Berlin, ), Behrmann et al. (Proceedings of HSCC'01, LNCS, vol. 2034, pp. 147-161, Springer, Berlin, ) are an extension of Alur and Dill (Theor. Comput. Sci. 126(2):183-235, ) timed automata, a widely accepted formalism for the modelling and verification of real time systems. Weighted timed automata extend timed automata by allowing costs on the locations and edges. There has been a lot of interest Bouyer et al. (Inf. Process. Lett. 98(5):188-194, ), Bouyer et al. (Log. Methods Comput. Sci. 4(2):9, ), Brihaye et al. (Proceedings of FORMATS/FTRTFT'04, LNCS, vol. 3253, pp. 277-292, Springer, Berlin, ), Brihaye et al. (Inf. Comput. 204(3):408-433, ) in studying the model checking problem of weighted timed automata. The properties of interest are written using logic weighted CTL (WCTL), an extension of CTL with costs. It has been shown Bouyer et al. (Log. Methods Comput. Sci. 4(2):9, ) that the problem of model checking WTAs with a single clock using WCTL with no external cost variables is decidable, while 3 clocks render the problem undecidable Bouyer et al. (Inf. Process. Lett. 98(5):188-194, ). The question of 2 clocks is open. In this paper, we introduce a subclass of weighted timed automata called weighted integer reset timed automata (WIRTA) and study the model checking problem. We give a clock reduction technique for WIRTA. Given a WIRTA $\mathcal{A}$ with n≥1 clocks, we show that a single clock WIRTA $\mathcal{A}'$ preserving the paths and costs of $\mathcal{A}$ can be obtained. This gives us the decidability of model checking WIRTA with n≥1 clocks and m≥1 costs using WCTL with no external cost variables. We then show that for a restricted version of WCTL with external cost variables, the model checking problem is undecidable for WIRTA with 3 stopwatch costs and 1 clock. Finally, we show that model checking WTA with 2 clocks and 1 stopwatch cost against WCTL with no external cost variables is undecidable, thereby answering a question that has remained long open. [ABSTRACT FROM AUTHOR]

We address the problem of reducing the size of (nondeterministic, bottom-up) tree automata (TA) using suitable, language-preserving equivalences on the states of the automata. In particular, we propose the so-called composed bisimulation equivalence as a new language preserving equivalence. A composed bisimulation equivalence is defined in terms of two different relations, namely the upward and downward bisimulation equivalence. We provide simple and efficient algorithms for computing these relations. The notion of composed bisimulation equivalence is motivated by an attempt to obtain an equivalence that can provide better reductions than what currently known bisimulation-based approaches can offer, but which is not significantly more difficult to compute (and hence stays below the computational requirements of simulation-based reductions). The experimental results we present in the paper show that our composed bisimulation equivalence meets such requirements, and hence provides users of TA with a finer way to resolve the trade-off between the available degree of reduction and its cost. [ABSTRACT FROM AUTHOR]

Antimirov and Mosses proposed a rewrite system for deciding the equivalence of two (extended) regular expressions. They argued that this method could lead to a better average-case algorithm than those based on the comparison of the equivalent minimal deterministic finite automata. In this paper we present a functional approach to that method, prove its correctness, and give some experimental comparative results. Besides an improved functional version of Antimirov and Mosses's algorithm, we present an alternative one using partial derivatives. Our preliminary results lead to the conclusion that, indeed, these methods are feasible and, most of the time, faster than the classical methods. [ABSTRACT FROM AUTHOR]

Abstract Standard pattern discovery techniques, such as association rules, suffer an extreme risk of finding very large numbers of spurious patterns for many knowledge discovery tasks. The direct-adjustment approach to controlling this risk applies a statistical test during the discovery process, using a critical value adjusted to take account of the size of the search space. However, a problem with the direct-adjustment strategy is that it may discard numerous true patterns. This paper investigates the assignment of different critical values to different areas of the search space as an approach to alleviating this problem, using a variant of a technique originally developed for other purposes. This approach is shown to be effective at increasing the number of discoveries while still maintaining strict control over the risk of false discoveries. [ABSTRACT FROM AUTHOR]

By explicit nondeterminism degree of a pushdown automata we mean the maximal number of choices in the transitions of the automata. In this paper we will prove that each pushdown automaton has an equivalent pushdown automaton with degree 1 of explicit nondeterminism, which implies that λ-moves in pda are sufficient to simulate nondeterminism. Moreover, from this normal form (i.e. pda with degree 1 of explicit nondeterminism) we can measure the amount of (implicit) nondeterminism. This measure will be used to determine a countable infinite hierarchy of contextfree language subclasses, whose bottom is the class of deterministic context-free languages and the top is the class of context-free languages. [ABSTRACT FROM AUTHOR]

This paper presents a novel system framework for interactive, three-dimensional, stylized, abstract painterly rendering. In this framework, the input models are first represented using 3D point sets and than this point-based representation is used to build a multiresolution bounding sphere hierarchy. From the leaf to root nodes, spheres of various sizes are rendered into multiple-size strokes on the canvas. The proposed sphere hierarchy is developed using multiscale region segmentation. This segmentation task assembles spheres with similar attribute regularities into a meaningful region hierarchy. These attributes include colors, positions, and curvatures. This hierarchy is very useful in the following respects: 1) it ensures the screen-space stroke density, 2) controls different input model abstractions, 3) maintains region structures such as the edges/boundaries at different scales, and 4) renders models interactively. By choosing suitable abstractions, brush stroke, and lighting parameters, we can interactively generate various painterly styles. We also propose a novel scheme that reduces the popping effect in animation sequences. Many different stylized images can be generated using the proposed framework. [ABSTRACT FROM AUTHOR]

Finite automata determinization is a critical operation for numerous practical applications such as regular expression search. Algorithms have to deal with the possible blow up of determinization. There exist solutions to control the space and time complexity like the so called "on the fly' determinization. Another solution consists in performing brute force determinization, which is robust and technically fast, although a priori its space complexity constitutes a weakness. However one can reduce this complexity by performing a partial brute force determinization. This paper provides optimizations that consist in detecting classes of unreachable states and transitions of the subset automation, which leads in average to an exponential reduction of the complexity of brute force and partial brute force determinization. [ABSTRACT FROM AUTHOR]

The paper formalizes two types of refinement for finite state machines: OR refinement and p-OR refinement. For each such type of refinement, it shows that, if the implementation is also constructed through a process of refinement, then the application of Chow's W test generation method can be distributed into smaller chunks, thus diminishing the effort devoted to testing and the size of the final test set. [ABSTRACT FROM AUTHOR]

One of the strengths of using a stream X-machine to specify a system is that, under certain well defined conditions, it is possible to produce a test set that is guaranteed to determine the correctness of the implementation. This testing method assumes that the processing functions are correctly implemented, therefore it only tests the integration of the processing functions implementations into the system implementation. This paper uses a case study to illustrate how this method can be extended so that it will no longer require the implementations of the processing functions to be proved correct before the actual system testing can take place. Instead, the testing of the processing functions is performed along with the integration testing. [ABSTRACT FROM AUTHOR]

Say that a nonzero c. e. degree b is a quasi-complement of a c. e. degree a if a ∩ b = 0 and a ∪ b is high. It is well-known (due to Shore) that each cappable degree has a high quasi-complement. However, by the existence of the almost deep degrees, there are nonzero cappable degrees having no low quasi-complements. In this paper, we prove that any nonzero cappable degree has a low2 quasi-complement. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

In this paper, we study semantic labelled tableaux for the propositional Bunched Implications logic (BI) that freely combines intuitionistic logic (IL) and multiplicative intuitionistic linear logic (MILL). BI is a resource-aware logic that captures interferences between resources and it is well suited, because of its resource-based sharing interpretation, for reasoning about mutable data structures. We propose a labelled tableau calculus for BI⊥1 based on particular labels and constraints. We prove the soundness and completeness of this calculus w.r.t. the Kripke resource semantics with emphasis on countermodel construction. In addition, we prove the finite model property and as a consequence the decidability of BI⊥. Moreover, we analyse some algorithmic aspects of the tableau construction by providing a free variable variant of the calculus. We also develop the restrictions to IL and MILL that provide new tableau methods for both logics with generation of countermodels. [ABSTRACT FROM PUBLISHER]

We defined and studied three different types of lattice-valued finite state quantum automata (LQA) and four different kinds of LQA operations, discussed their advantages, disadvantages, and various properties. There are four major results obtained in this paper. First, no one of the above mentioned LQA follows the law of lattice value conservation. Second, the theorem of classical automata theory, that each nondeterministic finite state automaton has an equivalent deterministic one, is not necessarily valid for finite state quantum automata. Third, we proved the existence of semilattices and also lattices formed by different types of LQA. Fourth, there are tight relations between properties of the original lattice l and those of the l-valued lattice formed by LQA. [ABSTRACT FROM AUTHOR]

This paper is concerned with a Petri net model having fuzzy timing and fuzzy real-time temporal logic. In an earlier paper, we introduced a Petri net model with four fuzzy set theoretic functions of time but no algorithms were given for computing the two important operators called, earliest and latest. In this paper, we first present algorithms for performing these two operations on fuzzy functions of time. Then we extend the existing concept of (real-time) metric temporal logic to fuzzy metric temporal logic by expressing the metrics for state and time constraints in terms of fuzzy possibility distributions. Finally we combine the two concepts of fuzzy-timing Petri net and fuzzy metric temporal logic to introduce a new Petri net model called the temporal-logic fuzzy-timing Petri net (TLFTN). The paper concludes with an algorithm and illustrative example for model checking using TLFTNs. © 1999 John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

This paper presents several branch and bound algorithms for a single-machine scheduling problem with batching. Jobs are partitioned into families, and a set-up time is necessary when there is a switch from processing jobs of one family to jobs of another family. The objective is to minimize the total weighted completion time. A lower bound based on Lagrangian relaxation of the machine capacity constraint is derived. Also, a multiplier adjustment method to find values of the multipliers is proposed. Computational experience with instances having up to 50 jobs shows that the lower bounds are effective in restricting the search. [ABSTRACT FROM AUTHOR]

In this paper, the problem of sequencing jobs on a single machine to minimize the weighted number of tardy jobs is considered. Some new dominances between jobs are proposed and studied. A new branch and bound algorithm that can solve large problems, e.g. 85 jobs, is presented. [ABSTRACT FROM AUTHOR]

In traditional automata theory, the closure with respect to certain operations is one of the most investigated properties, especially the methods of constructing automata for certain operations among the given sub-automata. However, up to now less effort has been addressed to this question for P automata. As an improvement on earlier results, we introduce P automata with communication and active membrane rules working in the initial mode (CAIP). We present methods for constructing automata that recognize the Union, the Concatenation, the Kleene Closure, or the ω Closure of the given languages which are represented by some P automata. We also show that for any language denoted by a regular expression, we can readily construct a CAIP automaton corresponding to it. [ABSTRACT FROM AUTHOR]

In 1984. Danecki proved that satisfiability in IPDL, i.e., Propositional Dynamic Logic (PDL) extended with an intersection operator on programs, is decidable in deterministic double exponential time. Since then, the exact complexity of IPDL has remained an open problem: the best known lower bound was the EXPTIME one stemming from plain PDL until, in 2004. the first author established EXPSAPCE-hardness. In this paper. we finally close the gap and prove that IPDL is hard for 2-EXPIME. thus 2-EXPTIME-complete. We then sharpen our lower bound, showing that it even applies to IPDL without the test operator interpreted on tree structures. [ABSTRACT FROM AUTHOR]

Set constraints form a constraint system where variables range over the domain of sets of trees. They give a natural formalism for many problems in program analysis. Syntactically, set constraints are conjunctions of inclusions between expressions built over variables, constructors (constants and function symbols from a given signature) and a choice of set operators that defines the specific class of set constraints. In this article, we are interested in the class of set constraints with projections, which is the class with all Boolean operators (union, intersection and complement) and projections that in program analysis directly correspond to type destructors. We prove that the problem of existence of a solution of a system of set constraints with projections is in NEXPTIME, and thus that it is NEXPTIME-complete. [ABSTRACT FROM AUTHOR]