足球视频镜头分类与球场区域检测

目的 足球视频镜头和球场区域是足球视频事件检测的必要条件,对于足球视频语义分析具有重要作用。针对现有镜头分类方法的不足,提出识别足球视频镜头类型的波动检测法。方法 该方法使用一个滑动窗口在视频帧图像中滑动,记录滑动窗口内球场像素比例在远镜头阈值上下的波动次数,根据波动次数判断镜头类型。对于足球场地区域分类,提出使用视频图像中球场区域的左上角和右上角点的位置关系识别球场区域类型的方法,该方法使用高斯混合模型识别出球场,根据球场在帧图像中左右边界坐标的高低判断球场区域类型,方法简单高效。结果 本文提出的两种方法与现有的分类方法相比,在准确率和召回率方面具有较大提高,检测效率高,可以满足实时性要求。结论 本文方法解决了传统滑动窗口法无法正确识别球场倾斜角度过大的帧图像,降低了传统球场区域检测方法依赖球场线检测而导致的准确率不高的问题。     

Automated solutions to incomplete jigsaw puzzles

The jigsaw puzzle re-assembly problem has been investigated only intermittently in the research literature. One potential theoretical line of research concerns jigsaw puzzles that do not have a complete set of puzzle pieces. These incomplete puzzles represent a difficult aspect of this problem that is outlined but can not be resolved in the current research. The computational experiments conducted in this paper demonstrate that the proposed re-assembly algorithm being optimised to re-assemble the complete jigsaw puzzles is not efficient when applied to the puzzles with missing pieces. Further work was undertaken to modify the proposed algorithm to enable efficient re-assembly of incomplete jigsaw puzzles. Consequently, a heuristic strategy, termed Empty Slot Prediction, was developed to support the proposed algorithm, and proved successful when applied to certain sub-classes of this problem. The results obtained indicate that no one algorithm can be used to solve the multitude of possible scenarios involved in the re-assembly of incomplete jigsaw puzzles. Other variations of the jigsaw puzzle problem that still remain unsolved are presented as avenues for future research.     

Pattern Databases

The efficiency of A* searching depends on the quality of the lower bound estimates of the solution cost. Pattern databases enumerate all possible subgoals required by any solution, subject to constraints on the subgoal size. Each subgoal in the database provides a tight lower bound on the cost of achieving it. For a given state in the search space, all possible subgoals are looked up in the pattern database, with the maximum cost over all lookups being the lower bound. For sliding tile puzzles, the database enumerates all possible patterns containing N tiles and, for each one, contains a lower bound on the distance to correctly move all N tiles into their correct final location. For the 15-Puzzle, iterative-deepening A* with pattern databases(N ="8) reduces the total number of nodes searched on a standard problem set of 100 positions by over 1000‐fold.     

Automatic Solution of Jigsaw Puzzles

We present a method for automatically solving apictorial jigsaw puzzles that is based on an extension of the method of differential invariant signatures. Our algorithms are designed to solve challenging puzzles, without having to impose any restrictive assumptions on the shape of the puzzle, the shapes of the individual pieces, or their intrinsic arrangement. As a demonstration, the method was successfully used to solve two commercially available puzzles. Finally we perform some preliminary investigations into scalability of the algorithm for even larger puzzles.     

Solving cross-matching puzzles using intelligent genetic algorithms

Cross-matching puzzles are logic based games being played with numbers, letters or symbols that present combinational problems. A cross-matching puzzle consists of three tables: solution table, detection table, and control table. The puzzle can be solved by superposing the detection and control tables. For the solution of the cross-matching puzzle, a depth first search method can be used, but by expanding the size of the puzzle, computing time can be increased. Hence, the genetic algorithm, which is one of the most common optimization algorithms, was used to solve cross-matching puzzles. The multi-layer genetic algorithm was improved for the solution of cross-matching puzzles, but the results of the multi-layer genetic algorithm were not good enough because of the expanding size of the puzzle. Therefore, in this study, the genetic algorithm was improved in an intelligent way due to the structure of the puzzle. The obtained results showed that an intelligent genetic algorithm can be used to solve cross-matching puzzles.     

数独基于规则的逐步枚举算法设计

给出了数独(Sudoku)的6条性质,并在此基础上提出了6条推理规则,然后结合空格填写的一个一组,两个一组及更多个一组的枚举算法,在枚举中进行推理.使推理和枚举结合起来,对有唯一解的数独问题,其求解速度比回溯法快得多,同时也能完成许多数独软件无法进行推理计算的数独难题.用两个数独难题进行验证,表明该方法十分有效.     

The three-color and two-color Tantrix™ rotation puzzle problems are NP-complete via parsimonious reductions

Holzer and Holzer [M. Holzer, W. Holzer, Tantrix? rotation puzzles are intractable, Discrete Applied Mathematics 144(3) (2004) 345–358] proved that the Tantrix? rotation puzzle problem with four colors is NP-complete, and they showed that the infinite variant of this problem is undecidable. In this paper, we study the three-color and two-color Tantrix? rotation puzzle problems (3-TRP and 2-TRP) and their variants. Restricting the number of allowed colors to three (respectively, to two) reduces the set of available Tantrix? tiles from 56 to 14 (respectively, to 8). We prove that 3-TRP and 2-TRP are NP-complete, which answers a question raised by Holzer and Holzer [M. Holzer, W. Holzer, Tantrix? rotation puzzles are intractable, Discrete Applied Mathematics 144(3) (2004) 345–358] in the affirmative. Since our reductions are parsimonious, it follows that the problems Unique-3-TRP and Unique-2-TRP are DP-complete under randomized reductions. We also show that the another-solution problems associated with 4-TRP, 3-TRP, and 2-TRP are NP-complete. Finally, we prove that the infinite variants of 3-TRP and 2-TRP are undecidable.     

A multi-layer framework for puzzle-based denial-of-service defense

Client puzzles have been advocated as a promising countermeasure to denial-of-service (DoS) attacks in recent years. However, how to operationalize this idea in network protocol stacks still has not been sufficiently studied. In this paper, we describe our research on a multi-layer puzzle-based DoS defense architecture, which embeds puzzle techniques into both end-to-end and IP-layer services. Specifically, our research results in two new puzzle techniques: puzzle auctions for end-to-end protection and congestion puzzles for IP-layer protection. We present the designs of these approaches and evaluations of their efficacy. We demonstrate that our techniques effectively mitigate DoS threats to IP, TCP and application protocols; maintain full interoperability with legacy systems; and support incremental deployment. We also provide a game theoretic analysis that sheds light on the potential to use client puzzles for incentive engineering: the costs of solving puzzles on an attackers’ behalf could motivate computer owners to more aggressively cleanse their computers of malware, in turn hindering the attacker from capturing a large number of computers with which it can launch DoS attacks.     

A parallel algorithm for the eight‐puzzle problem using analogical reasoning

The emphasis in this article will be on people's analogical use of fairly explicit pieces of knowledge in problem solving situations. Analogical reasoning (AR) has long been recognized as an important component of problem solving. In general, AR involves using the (possibly modified) solution of one problem to solve another. The preconditions that need to be satisfied in order to apply AR are to locate the common features that are shared among the two problems. The case study considered here is the eight‐puzzle problem. The underlying learning is a three‐stage process. First, is the building stage, where heuristic search techniques are used to find solutions to a set of initial puzzles. The next stage, the reminding stage, identifies a group of solutions with similar properties to the input puzzle (supposedly, this puzzle is solvable). During the final stage, the analogical transformation stage, many movement operators are applied to similar solutions already extracted from the reminding stage, in order to find the solution to the original (input) puzzle. One of the major drawbacks is that AR requires a lot of computational power for global searching before it can be converged. Therefore, in order to outperform heuristic algorithms, a parallel version of AR is introduced. Parallel computation is focused on the last two stages of AR. A design and analysis of parallel algorithms of the reminding stage and the analogical transformation stage are presented. © 2002 Wiley Periodicals, Inc.     

An evolutionary-based hyper-heuristic approach for the Jawbreaker puzzle

In this paper a hyper-heuristic algorithm is designed and developed for its application to the Jawbreaker puzzle. Jawbreaker is an addictive game consisting in a matrix of colored balls, that must be cleared by popping sets of balls of the same color. This puzzle is perfect to be solved by applying hyper-heuristics algorithms, since many different low-level heuristics are available, and they can be applied in a sequential fashion to solve the puzzle. We detail a set of low-level heuristics and a global search procedure (evolutionary algorithm) that conforms to a robust hyper-heuristic, able to solve very difficult instances of the Jawbreaker puzzle. We test the proposed hyper-heuristic approach in Jawbreaker puzzles of different size and difficulty, with excellent results.     

A commentary and correction on the article “Pansharpening by exploiting sharpness of the spatial structure”

This study clarifies the implicit potential deficiency caused by the sparse cardinality parameter k in Rong et al. (2014). In addition, k = β × W × M × N (0.9 ≤ β < 1) is suggested to avert this potential deficiency, where β is a ratio controlling the amount of sparse cardinality, W is the number of multispectral bands and M × N is the size of panchromatic image. With the choice of k suggested in this study, the low rank matrix L and sparse matrix S obtained by Go Decomposition (Zhou and Tao 2011) can be iteratively optimized and solved. Thus, instead of choosing k as W × M × N in Rong et al. (2014), the potential deficiency that L is directly obtained as an analytic solution can be averted.     

Biomechanical analysis of upper limb during the use of touch screen: motion strategies identification

Abstract

Nowadays touch technology is growing and developers try to make it ever more intuitive and easier to use. This present work focused on the upper limb joint coordination during the achievement of puzzles on touch screen. A 5-inch and 10-inch devices were used to perform 9 and 16 pieces puzzles dragged with digits. The conclusions showed an increase in joint solicitation with the number of piece and the touch screen size. Moreover, three interactions strategies proved to be an evidence: the ‘wrist strategy’ preferentially implying wrist flexion/extension, the ‘elbow strategy’ preferentially implying the elbow flexion/extension and the ‘neutral strategy’ mobilising equally the two joints. From an ergonomic point of view, the data about how the upper limb segments are mobilised while interacting with the screen could be relevant to increase the adaptability of the devices to the user, including users with motor impairments.

Practitioner Summary: Information about the biomechanical organisation of movement during interaction with touch devices appears relevant in order to develop applications adapted to the motor capacities of users. From the analysis of joint angles when performing several times a puzzle with healthy subjects, three motor strategies were highlighted.     

单源点最短路径动态优化算法

设计了最短路径时间复杂度取决于边数e和点数n的动态优化算法。采用了独特的动态PV集合链,改进了当前求得的最短路径向量D的存储结构,用PV集合链对向量D进行动态管理,使其时间开销为e+(n-1)×(n-2)/2+3n。当n>4时,SPD OA算法的性能明显优于Dijkstra算法,呈现出良好的动态优化特性。最后对动态优化算法与Dijkstra算法用理论公式得出的数据进行了时间性能比较。     

Classification of the entangled states 2 × M × N

We extend the matrix decomposition method (MDM) in classifying the 2 × N × N truly entangled states to 2 × M × N system under the condition of stochastic local operations and classical communication. It is found that the MDM is quite practical and convenient in operation for the asymmetrical tripartite states, and an explicit example of the classification of 2 × 6 × 7 quantum system is presented.     

ALAN TURING: THE ENIGMA – BOOK REVIEW

Abstract

Simple substitution ciphers are a class of puzzles often found in newspapers, in which each plaintext letter is mapped to a fixed ciphertext letter and spaces are preserved. In this article, a system for automatically solving them is described even when the ciphertext is too short for statistical analysis, and when the puzzle contains non-dictionary words. The approach is based around a dictionary attack; several important performance optimizations are described as well as effective techniques for dealing with non-dictionary words. Quantitative performance results for several variations of the approach and two other implementations are presented.     

CRYPTANALYSTS' CORNER

Abstract

The Hill cipher, also known as matrix encryption, is a polygraphic substitution cipher, developed by the mathematician Lester S. Hill in 1929. While various attacks had been known on the Hill cipher, the ciphertext-only attack without assumptions about the encryption matrix or probable plaintext words was introduced only recently by Bauer and Millward. They obtained high efficiency of attack by recovering the decryption matrix row by row rather than all rows at once. In this paper, we extend their ciphertext-only attack in two ways. First, we present a better scoring system for cryptanalysis based on the goodness-of-fit statistics. Specifically, we reduce the average number of candidate rows from 24.83 to 7.00 for 3 × 3 matrix and from 4027.78 to 1220.38 for 4 × 4 matrix. Second, we show how to apply our attacks to the Hill cipher without knowing the numeric equivalents of the letters of the plaintexts.     

An automatic solver for very large jigsaw puzzles using genetic algorithms

In this paper we propose the first effective genetic algorithm (GA)-based jigsaw puzzle solver. We introduce a novel crossover procedure that merges two “parent” solutions to an improved “child” configuration by detecting, extracting, and combining correctly assembled puzzle segments. The solver proposed exhibits state-of-the-art performance, as far as handling previously attempted puzzles more accurately and efficiently, as well puzzle sizes that have not been attempted before. The extended experimental results provided in this paper include, among others, a thorough inspection of up to 30,745-piece puzzles (compared to previous attempts on 22,755-piece puzzles), using a considerably faster concurrent implementation of the algorithm. Furthermore, we explore the impact of different phases of the novel crossover operator by experimenting with several variants of the GA. Finally, we compare different fitness functions and their effect on the overall results of the GA-based solver.     

融合人工求解策略的数独回溯求解法

数独有唯一解,回溯法可以保证获得正确结果。为了提高回溯法求解效率,向前搜索用最基础的人工策略进行求解,这样只需要两三个正确的候选数就可求解成功。基础人工策略求解的结果分为求解成功、求解失败和求解不确定三种情况,只有在求解不确定时才继续向前搜索,从而达到高效剪枝的目的;同时在算法实施方面采用大量位运算,大量9×9数独的实验结果表明对于绝大部分数独,平均计算时间不超过0.15 ms,对于那些极端困难的数独平均求解时间为2 ms;求解一个16×16数独的平均时间为224 ms。通过实验还发现17个提示数的9×9数独数据集在各方面具有较好的分散性,建议作为标准测试用数据集。     

Influence of social presence on eye movements in visual search tasks

Abstract

This study employed an eye-tracking technique to investigate the influence of social presence on eye movements in visual search tasks. A total of 20 male subjects performed visual search tasks in a 2 (target presence: present vs. absent) × 2 (task complexity: complex vs. simple) × 2 (social presence: alone vs. a human audience) within-subject experiment. Results indicated that the presence of an audience could evoke a social facilitation effect on response time in visual search tasks. Compared with working alone, the participants made fewer and shorter fixations, larger saccades and shorter scan path in simple search tasks and more and longer fixations, smaller saccades and longer scan path in complex search tasks when working with an audience. The saccade velocity and pupil diameter in the audience-present condition were larger than those in the working-alone condition. No significant change in target fixation number was observed between two social presence conditions.

Practitioner Summary: This study employed an eye-tracking technique to examine the influence of social presence on eye movements in visual search tasks. Results clarified the variation mechanism and characteristics of oculomotor scanning induced by social presence in visual search.