A model for the gray-intensity distribution of historical handwritten documents and its application for binarization

In this article, our goal is to describe mathematically and experimentally the gray-intensity distributions of the fore- and background of handwritten historical documents. We propose a local pixel model to explain the observed asymmetrical gray-intensity histograms of the fore- and background. Our pixel model states that, locally, the gray-intensity histogram is the mixture of gray-intensity distributions of three pixel classes. Following our model, we empirically describe the smoothness of the background for different types of images. We show that our model has potential application in binarization. Assuming that the parameters of the gray-intensity distributions are correctly estimated, we show that thresholding methods based on mixtures of lognormal distributions outperform thresholding methods based on mixtures of normal distributions. Our model is supported with experimental tests that are conducted with extracted images from DIBCO 2009 and H-DIBCO 2010 benchmarks. We also report results for all four DIBCO benchmarks.     

A queueing theoretic approach for performance evaluation of low-power multi-core embedded systems

With Moore’s law supplying billions of transistors on-chip, embedded systems are undergoing a transition from single-core to multi-core to exploit this high transistor density for high performance. However, the optimal layout of these multiple cores along with the memory subsystem (caches and main memory) to satisfy power, area, and stringent real-time constraints is a challenging design endeavor. The short time-to-market constraint of embedded systems exacerbates this design challenge and necessitates the architectural modeling of embedded systems to reduce the time-to-market by expediting target applications to device/architecture mapping. In this paper, we present a queueing theoretic approach for modeling multi-core embedded systems that provides a quick and inexpensive performance evaluation both in terms of time and resources as compared to the development of multi-core simulators and running benchmarks on these simulators. We verify our queueing theoretic modeling approach by running SPLASH-2 benchmarks on the SuperESCalar simulator (SESC). Results reveal that our queueing theoretic model qualitatively evaluates multi-core architectures accurately with an average difference of 5.6% as compared to the architectures’ evaluations from the SESC simulator. Our modeling approach can be used for performance per watt and performance per unit area characterizations of multi-core embedded architectures, with varying number of processor cores and cache configurations, to provide a comparative analysis.     

Feature-based tuning of simulated annealing applied to the curriculum-based course timetabling problem

We consider the university course timetabling problem, which is one of the most studied problems in educational timetabling. In particular, we focus our attention on the formulation known as the curriculum-based course timetabling problem (CB-CTT), which has been tackled by many researchers and for which there are many available benchmarks.The contribution of this paper is twofold. First, we propose an effective and robust single-stage simulated annealing method for solving the problem. Second, we design and apply an extensive and statistically-principled methodology for the parameter tuning procedure. The outcome of this analysis is a methodology for modeling the relationship between search method parameters and instance features that allows us to set the parameters for unseen instances on the basis of a simple inspection of the instance itself. Using this methodology, our algorithm, despite its apparent simplicity, has been able to achieve high quality results on a set of popular benchmarks.A final contribution of the paper is a novel set of real-world instances, which could be used as a benchmark for future comparison.     

Firing patterns transition induced by system size in coupled Hindmarsh-Rose neural system

The effect of system size on the different dynamical states in coupled cell system is numerically investigated, by using the Hindmarsh-Rose (HR) model. We select the external current as a controlling parameter, for the proper coupling intensity, it is found that the system undergoes the transition of neural firing patterns from one state to another one, when the number of neurons in coupled system is set to be a proper value. And if the coupled system is turned below the bifurcation point, we find that such transition behavior can occur both between two different periodic states, or periodic state and chaotic one. These phenomena imply the occurrence of firing patterns transition (FPT) induced by system size in this coupled system. Furthermore, if we select r as a controlling parameter, we can also find the similar transition behavior can also be observed, and find that such transition behaviors may have some inherent relevance with the activity degree. Finally, we simply gave the reason for difference direction of FPT. Our results indicate the HR system may make an effective response to external stimulus by adjusting itself parameter, and using this transition mode.     

Loop summarization using state and transition invariants

This paper presents algorithms for program abstraction based on the principle of loop summarization, which, unlike traditional program approximation approaches (e.g., abstract interpretation), does not employ iterative fixpoint computation, but instead computes symbolic abstract transformers with respect to a set of abstract domains. This allows for an effective exploitation of problem-specific abstract domains for summarization and, as a consequence, the precision of an abstract model may be tailored to specific verification needs. Furthermore, we extend the concept of loop summarization to incorporate relational abstract domains to enable the discovery of transition invariants, which are subsequently used to prove termination of programs. Well-foundedness of the discovered transition invariants is ensured either by a separate decision procedure call or by using abstract domains that are well-founded by construction. We experimentally evaluate several abstract domains related to memory operations to detect buffer overflow problems. Also, our light-weight termination analysis is demonstrated to be effective on a wide range of benchmarks, including OS device drivers.     

Complexity results for standard benchmark domains in planning

The efficiency of AI planning systems is usually evaluated empirically. For the validity of conclusions drawn from such empirical data, the problem set used for evaluation is of critical importance. In planning, this problem set usually, or at least often, consists of tasks from the various planning domains used in the first two international planning competitions, hosted at the 1998 and 2000 AIPS conferences. It is thus surprising that comparatively little is known about the properties of these benchmark domains, with the exception of Blocksworld, which has been studied extensively by several research groups.In this contribution, we try to remedy this fact by providing a map of the computational complexity of non-optimal and optimal planning for the set of domains used in the competitions. We identify a common transportation theme shared by the majority of the benchmarks and use this observation to define and analyze a general transportation problem that generalizes planning in several classical domains such as Logistics, Mystery and Gripper. We then apply the results of that analysis to the actual transportation domains from the competitions. We next examine the remaining benchmarks, which do not exhibit a strong transportation feature, namely Schedule and FreeCell.Relating the results of our analysis to empirical work on the behavior of the recently very successful FF planning system, we observe that our theoretical results coincide well with data obtained from empirical investigations.     

RUGRAT: Evaluating program analysis and testing tools and compilers with large generated random benchmark applications

Benchmarks are heavily used in different areas of computer science to evaluate algorithms and tools. In program analysis and testing, open‐source and commercial programs are routinely used as benchmarks to evaluate different aspects of algorithms and tools. Unfortunately, many of these programs are written by programmers who introduce different biases, not to mention that it is very difficult to find programs that can serve as benchmarks with high reproducibility of results. We propose a novel approach for generating random benchmarks for evaluating program analysis and testing tools and compilers. Our approach uses stochastic parse trees, where language grammar production rules are assigned probabilities that specify the frequencies with which instantiations of these rules will appear in the generated programs. We implemented our tool for Java and applied it to generate a set of large benchmark programs of up to 5M lines of code each with which we evaluated different program analysis and testing tools and compilers. The generated benchmarks let us independently rediscover several issues in the evaluated tools. Copyright © 2014 John Wiley & Sons, Ltd.     

Solving the SPARQL query containment problem with SpeCS

The query containment problem is a fundamental computer science problem which was originally defined for relational queries. With the growing popularity of the sparql query language, it became relevant and important in this new context: reliable and efficient sparql query containment solvers may have various applications within static analysis of queries, especially in the area of query optimizations and refactoring. In this paper, we present a new approach for solving the query containment problem in sparql. The approach is based on reducing the query containment problem to the satisfiability problem in first order logic. It covers a wide range of the sparql language constructs, including union of conjunctive queries, blank nodes, projections, subqueries, clauses from, filter, optional, graph, etc. It also covers containment under rdf schema entailment regime, and it can deal with the subsumption relation. We describe an implementation of the approach, an open source solver SpeCS and its thorough experimental evaluation on two relevant benchmarks, Query Containment Benchmark and SQCFramework. As a side result, SpeCS identified incorrect test cases within both benchmarks, which were manually checked, confirmed and fixed, resulting in better and more reliable benchmarks. The evaluation also shows that SpeCS is highly efficient and that compared to the state-of-the-art solvers, it gives more precise results in a shorter amount of time. In addition, SpeCS has the highest coverage of the supported language constructs.     

A matheuristic for the firefighter problem on graphs

In this paper, we describe a computational study conducted on The Firefighter Problem (FFP ), which models fire spreading and containment in a graph. Once the fire breaks out on a set of vertices, the goal is to save as many vertices as possible with limited resources. Practical applications of the FFP occur in areas such as disease control and network security. The FFP is NP‐hard and heuristics have been proposed earlier. Our main contributions include improvements to an existing integer linear programming formulation that led to an average speedup of two to compute exact solutions. Moreover, we developed a novel matheuristic, a technique based on the interoperation between metaheuristics and mathematical programming. We performed extensive experiments on public benchmarks both for parameter tuning and for comparison of our results with those from the literature. A rigorous statistical analysis shows that our new matheuristic outperforms the existing approaches.     

Precise shape analysis using field sensitivity

We present a static shape analysis technique to infer the shapes of the heap structures created by a program at run time. Our technique is field sensitive in that it uses field information to compute the shapes. The shapes of the heap structures are computed using two components: (a) Boolean functions that capture the shape transitions due to the update of a field in a structure, and (b) through path matrices that store approximate path information between two pointer variables. We classify the shapes as one of Tree, Directed Acyclic Graph (DAG) and Cycle. The novelty of our approach lies in the way we use field information to remember the fields that cause a heap structure to have a particular shape (Tree, DAG or Cycle). This allows us to easily identify the field updates that cause shape transitions from Cycle to DAG, from Cycle to Tree and from DAG to Tree. This makes our analysis more precise as compared to earlier shape analyses that ignore the fields participating in the formation of a shape. We implemented our analysis in GCC as a dynamic plug-in as an interprocedural data-flow analysis and evaluated it on some standard benchmarks against a field-insensitive shape analysis technique as a baseline approach. We are able to achieve significant precision as compared to the baseline analysis (at the cost of increase in analysis time). In particular, we are able to infer more precise shapes for 4 out 7 Olden benchmarks, and never detect more cycles than the baseline analysis. We further suggest enhancements to improve the precision of our analysis under some constraints and to improve the analysis time at the cost of precision.     

Supporting simultaneous versions for software evolution assessment

When reengineering software systems, maintainers should be able to assess and compare multiple change scenarios for a given goal, so as to choose the most pertinent one. Because they implicitly consider one single working copy, revision control systems do not scale up well to perform simultaneous analyses of multiple versions of systems. We designed Orion, an interactive prototyping tool for reengineering, to simulate changes and compare their impact on multiple versions of software source code models. Our approach offers an interactive simulation of changes, reuses existing assessment tools, and has the ability to hold multiple and branching versions simultaneously in memory. Specifically, we devise an infrastructure which optimizes memory usage of multiple versions for large models. This infrastructure uses an extension of the FAMIX source code meta-model but it is not limited to source code analysis tools since it can be applied to models in general. In this paper, we validate our approach by running benchmarks on memory usage and computation time of model queries on large models. Our benchmarks show that the Orion approach scales up well in terms of memory usage, while the current implementation could be optimized to lower its computation time. We also report on two large case studies on which we applied Orion.     

A synthetic biology approach to bio-chem-ICT: first moves towards chemical communication between synthetic and natural cells

In this article we present novel aspects of the impact that synthetic biology (SB) can express in a field traditionally based on computer science: information and communication technologies (ICTs), an area that we will consider taking into account also possible implications for artificial intelligence (AI) research. In the first part of this article we will shortly introduce some recent theoretical and experimental issues related to our approach in SB, discussing their relevance and potentiality in the field. Next, we define an original SB research programme that aims at contributing to the development of bio-chem-ICTs and AI based on chemical communication between natural and synthetic cells. In particular we present (i) a mathematical model that allows us to simulate the main features of the system under construction; and (ii) preliminary wet-lab experiments showing the feasibility of our research programme. Based on the bottom-up construction of synthetic cells, the traits of this novel approach and their connections with recent conceptual and technological trends are finally discussed.     

Metrics for Action-labelled Quantitative Transition Systems

This paper defines action-labelled quantitative transition systems as a general framework for combining qualitative and quantitative analysis. We define state-metrics as a natural extension of bisimulation from non-quantitative systems to quantitative ones. We then prove that any single state-metric corresponds to a bisimulation and that the greatest state-metric corresponds to bisimilarity. Furthermore, we provide two extended examples which show that our results apply to both probabilistic and weighted automata as special cases of action-labelled quantitative transition systems.     

从OOA到OOD

本文在总结了面向对象分析与设计两阶段的主要工作的基础之上，着重探讨了面向对象分析与设计的边界划分问题，较详尽地分析了从分析阶段到设计阶段的过渡所涉及的工作及其难易，并提出了一些为顺利进行过渡应遵循的原则和建议。     

Transition thresholds and transition operators for binarization and edge detection

The transition method for image binarization is based on the concept of t-transition pixels, a generalization of edge pixels, and t-transition sets. We introduce a novel unsupervised thresholding for unimodal histograms to estimate the transition sets. We also present dilation and incidence transition operators to refine the transition set. Afterward, we propose the simple edge transition operator for detecting edges. Our experiments show that the new approach increases the effectiveness of OCR applications outperforming several top-ranked binarization algorithms.     

Analysis of the Petri net model of parallel manufacturing processes with shared resources

A method of analysis for a class of Petri nets (PNs) called parallel process net with resources (PPNRs) is presented in this paper. The proposed analysis method is based on reduced reachability graph (RRG) of PPNRs to verify the correspondence between required specification of manufacturing system and its PN representation. In order to reduce the reachability graph (RG), a new technique is proposed which incorporates the transition vectors (TVs) to determine all the enabled transitions at a given state of system and to recognize them as dependent or independent. An algorithm, based on the idea of simultaneous execution of concurrently enabled independent transitions, is developed to reduce the RG and its analysis is also performed. Moreover, relationship between the reduction of RG and parallel structure in the PN model is discovered. The proposed technique replaces the RG by a structure which directly depicts concurrent execution and does not show the irrelevant states by presenting the concurrent behavior of system in the reduced state space. The analysis of PPNRs based on RRG generated by proposed method is also presented and demonstrated by a practical example.     

IPv4/IPv6过渡机制的研究与实现

IPv6是面向下一代因特网的IP协议。与IPv4相比,IPv6有许多优点,例如提供更大的地址空间,提供路由聚集和即插即用等自动配置功能,因而提高了因特网的扩展性、可管理性等性能。在因特网全部采用IPv6之前,显然会存在一个需要v4和v6共存和相互通信的过渡期。在过渡期间,必须要有一整套强有力的、灵活的v4到v6过渡机制。该文对目前各种过渡机制进行了分析,重点研究了能使IPv4和IPv6直接互通的转换器NAT-PT,给出了设计的总体方案和实现过程,并在实际的网络环境下进行了测试,证明了文章实现的转换器是可行和实用的。     

Ultra-fast Lensless Computational Imaging through 5D Frequency Analysis of Time-resolved Light Transport

Light transport has been analyzed extensively, in both the primal domain and the frequency domain. Frequency analyses often provide intuition regarding effects introduced by light propagation and interaction with optical elements; such analyses encourage optimal designs of computational cameras that efficiently capture tailored visual information. However, previous analyses have relied on instantaneous propagation of light, so that the measurement of the time dynamics of light–scene interaction, and any resulting information transfer, is precluded. In this paper, we relax the common assumption that the speed of light is infinite. We analyze free space light propagation in the frequency domain considering spatial, temporal, and angular light variation. Using this analysis, we derive analytic expressions for information transfer between these dimensions and show how this transfer can be exploited for designing a new lensless imaging system. With our frequency analysis, we also derive performance bounds for the proposed computational camera architecture and provide a mathematical framework that will also be useful for future ultra-fast computational imaging systems.     

A logical approach to efficient Max-SAT solving

Weighted Max-SAT is the optimization version of SAT and many important problems can be naturally encoded as such. Solving weighted Max-SAT is an important problem from both a theoretical and a practical point of view. In recent years, there has been considerable interest in finding efficient solving techniques. Most of this work focuses on the computation of good quality lower bounds to be used within a branch and bound DPLL-like algorithm. Most often, these lower bounds are described in a procedural way. Because of that, it is difficult to realize the logic that is behind.In this paper we introduce an original framework for Max-SAT that stresses the parallelism with classical SAT. Then, we extend the two basic SAT solving techniques: search and inference. We show that many algorithmic tricks used in state-of-the-art Max-SAT solvers are easily expressible in logical terms in a unified manner, using our framework.We also introduce an original search algorithm that performs a restricted amount of weighted resolution at each visited node. We empirically compare our algorithm with a variety of solving alternatives on several benchmarks. Our experiments, which constitute to the best of our knowledge the most comprehensive Max-SAT evaluation ever reported, demonstrate the practical usability of our approach.     

A simple method for protein structural classification

Since the concept of structural classes of proteins was proposed, the problem of protein classification has been tackled by many groups. Most of their classification criteria are based only on the helix/strand contents of proteins. In this paper, we proposed a method for protein structural classification based on their secondary structure sequences. It is a classification scheme that can confirm existing classifications. Here a mathematical model is constructed to describe protein secondary structure sequences, in which each protein secondary structure sequence corresponds to a transition probability matrix that characterizes and differentiates protein structure numerically. Its application to a set of real data has indicated that our method can classify protein structures correctly. The final classification result is shown schematically. So it is visual to observe the structural classifications, which is different from traditional methods.