不确定性下强Berge均衡的存在性

在已知不确定参数变化的范围下,研究了非合作博弈与广义非合作博弈的强Berge均衡的存在性,基于强Berge均衡与不确定性下非合作博弈的强Nash均衡的概念,给出了不确定参数下非合作博弈与广义非合作博弈的强Berge均衡的定义,并利用Fan-Glicksberg不动点定理证明其存在性,最后用算例验证其可行性.     

The Impact of a Multiyear Systemic Reform Effort on Rural Elementary School Students' Science Achievement

This paper is a report of the impact of an externally funded, multiyear systemic reform project on students' science achievement on a modified version of the Third International Mathematics and Science Study (TIMSS) test in 33 small, rural school districts in two Midwest states. The systemic reform effort utilized a cascading leadership strategy of professional development delivered at summer workshops and through distance technologies and local leadership groups that focused on helping teachers work in communities of practice to adapt science inquiry lessons to teach and reinforce strategies and skills in language arts in the lessons. Science achievement scores of Grade 3 and Grade 6 student cohorts on the two forms of the TIMSS administered at the beginning, middle, and end of the professional development effort revealed a V‐shaped pattern of scores, suggesting that teachers struggled with the newly adapted science inquiries at first but then became more effective in their use. The impact of the adaptation strategy on the students' achievement, questions about the time needed for new instructional strategies to be embraced by teachers, and the wisdom of using “low stakes” achievement tests in studies are discussed.     

Factors influencing first-year students' success in mathematics

Qualitative data from lecturers and students were used to identify factors which were perceived as making the most important contributions to students' academic success or failure in first-year mathematics courses. The study was conducted in three phases involving exploratory open-ended questionnaires, Likert-type questionnaires, and interviews. The results highlight both areas of similarities and areas of differences in lecturers' and students' perceptions about influences on student success and failure. While both students and lecturers acknowledged the importance of motivation, differences in perceptions suggest further research is needed in the areas of active learning, help-seeking, and student effort and workload.     

Non-cooperative n-person game with a stopped set

A continuous time non-cooperative n-person Markov game with a stopped set is studied in this paper. We prove that, in the game process with or without discount factor, there exists an optimal stationary point of strategies, called the equilibrium point, and each player has his equilibrium stationary strategy, such that the total expected discounted or non-discounted gain are maximums.     

Using Similarities and Differences: A Meta‐Analysis of Its Effects and Emergent Patterns

The purpose of the study was to update previous meta‐analytic findings on the effectiveness of using similarities and differences as an instructional strategy. The strategy includes facilitating student comparison, classification, use of analogies, and use of metaphors. Previously, Marzano, Pickering, and Pollock reported a mean effect size of 1.61. For the present meta‐analysis, literature was searched to locate experimental studies meeting the following inclusion criteria: published between 1998 and 2008; examined effects of facilitating student comparison, classification, use of analogies, and use of metaphors; measured student academic achievement as an outcome; involved students in kindergarten through grade 12; and provided data necessary to compute effect sizes. Based on the eligible research, the overall mean effect size (Hedges' g) was .65, confirming earlier results indicating that using similarities and differences positively influences student achievement. Type of control group, however, moderated the effect. Larger effect sizes were associated with control groups receiving textbook‐guided instruction versus those receiving interactive instruction. Emergent patterns were observed for the positive influence of long‐term instruction, systematic instruction, supportive cuing, and opportunity for reflection and discussion. Results support recommendations to guide students through analogical reasoning about, and classification of, important concepts and relationships in content‐area instruction.     

Nash fuzzy equilibrium: Theory and application to a spatial duopoly

Consider a non-cooperative n-persons game. Each gambler has a set of mixed strategies at his disposal. The payoffs are some physical or immaterial objects. The game is a fuzzy game because (1) gamblers have more or less precise preferences for the payoffs and (2) the outcoming of payoffs is uncertain. The uncertainty can be expressed either by a distribution of possibility or by a distribution of probability. The product set of a gambler's mixed strategies is convex and compact and the payoff functions are continuous. Then a closed and convex fuzzy point-to-set mapping is defined on the product set of strategies and, by using a Butnariu theorem, the existence of a fixed point for this fuzzy point-to-set mapping is proved. The issue allows us to generalize a famous Nash result: a n-persons non-cooperative fuzzy game with mixed strategies has at least one equilibrium point. In the second part of the paper an economic application is devoted to the statement of the equilibrium existence conditions in a spatial duopoly. The model is not only more general than the classical ones, but also more relevant because new results are obtained.     

Does cooperation in auditing matter? A comparison of a non-cooperative and a cooperative game model of auditing

A game model of auditing including internal control investigation and substantive testing is analysed as a non-cooperative game. It is shown that in order for the presumed socially desirable outcome of high and honest effort by all to be obtained, it is necessary to adjust the cost structure to ameliorate the costs of not-qualifying erroneous accounts if the auditor can prove he or she has worked hard. Comparison with a cooperative game analysis of the model shows that there is a region of parameters where both cooperative and non-cooperative versions of the game lead to this socially desirable outcome. The significance of this result is that whilst society expects an ‘independent’ auditor not to cooperate with the auditee, the practical realities of auditing require a considerable degree of cooperation. This leads to an ‘expectations gap’ between what society expects and what actually happens, except in those cost regions where both the cooperative and non-cooperative versions of the audit game lead to the same solution.     

FiniteN-person non-cooperative games with unique equilibrium points

A necessary and sufficient condition is found for a given completely mixed strategyN-tuple to be the unique equilibrium point of some finiteN-person non-cooperative game.     

One-to-many non-cooperative matching games

We study a strategic model of wage negotiations between firms and workers. First, we define the stability of an allocation in an environment where firms can employ more than one worker. Secondly, we develop a one-to-many non-cooperative matching game, which is an extension of Kamecke’s one-to-one non-cooperative matching game. The main result shows the equivalence between the stable allocations and the outcomes of the subgame equilibria in the matching game: for any stable allocation in this game there is a subgame perfect equilibrium which induces the allocation on the equilibrium path, and every subgame perfect equilibrium induces a stable allocation on the equilibrium path. Furthermore, as for the existence of a stable allocation, we argue that a stable allocation, as with a subgame perfect equilibrium, does not always exist, but it exists under some conditions, using Kelso and Crawford’s modelling.     

The impact of metacognitive practice and teacher feedback on academic achievement in mathematics

The purpose of this study is to determine the effects of metacognitive strategies and content‐specific feedback on student achievement in high school mathematics. Participants consisted of a convenience sample of students in honors geometry. An analysis of variance with repeated measures was employed to address the research questions. For both the posttest and retention test, students in the experimental group significantly outperformed the students in the comparison group. However, students scored lower in the retention test than the posttest. The findings of this study offer a modest contribution to the body of empirical research on the impact of metacognitive practice and content‐specific feedback on academic achievement at the high school level.     

Deterministic Time-inconsistent Optimal Control Problems - an Essentially Cooperative Approach

A general deterministic time-inconsistent optimal control problem is formulated for ordinary differential equations. To find a time-consistent equilibrium value function and the corresponding time-consistent equilibrium control, a non-cooperative N-person differential game (but essentially cooperative in some sense) is introduced. Under certain conditions, it is proved that the open-loop Nash equilibrium value function of the N -person differential game converges to a time-consistent equilibrium value function of the original problem, which is the value function of a time-consistent optimal control problem. Moreover, it is proved that any optimal control of the time-consistent limit problem is a time-consistent equilibrium control of the original problem.     

Non-cooperative implementation: A survey of recent results

Strategic decentralization of collective decision-making is considered when the agents' behaviour is non-cooperative. Specifically they use dominant, maximin risk-avert or sophisticated strategies. The existing results applying these equilibrium concepts are reviewed in three familiar economically meaningful contexts: ordinal (as in voting), random (as in bargaining) and quasilinear (as in public goods problems).     

考虑声誉效应的网络众包参与者行为博弈模型及仿真分析

为了控制网络众包交易的风险,以网络众包平台中的发包方和接包方为研究对象,基于微分博弈方法建立了网络众包交易中参与者行为的博弈模型,研究了发包方和接包方在合作和非合作两种情形下的策略选择。本文研究发现在声誉效应满足特定阈值的条件时,合作博弈情形下众包系统的总收益更大;而且,发包方和接包方违约控制的收益及努力程度更大。在网络众包平台的违约罚金超过特定阈值时,随时间推移发包方和接包方违约控制的努力程度逐渐提高,实现帕累托改进。本文结合猪八戒网、InnoCentive等网络众包平台的众包交易机制,采用数值分析对博弈模型的求解结果进行模拟。对于网络众包平台来说,可以通过建立有效的信用评价机制,将信用评价或声誉纳入众包交易定价,引导参与者约束自身行为。     

Relationships Between Student,Teacher, and School Characteristics and Mathematics Achievement

A variety of factors contributes to student achievement in mathematics, including but not limited to student behaviors and student, teacher, and school characteristics. The purpose of this study was to explore which of these factors have an impact on student mathematics achievement. The target population for this study was North Carolina Algebra II students. Analyses of variance models were examined for group differences and a Three‐level Hierarchical Linear Modeling method was employed to examine individual predictors of student achievement in mathematics. Statistically, significant differences were found between students of different ethnicities, socioeconomic statuses (SES), and parental education levels. No gender effects were statistically significant. All teacher‐level variables investigated were found to be statistically significant, impacting student achievement in mathematics. School size and SES were not found to significantly contribute to student achievement. More research on the relationships between these factors shown to make statistically significant differences on mathematics achievement is needed to further explain several phenomena that this research reveals.     

考虑相互依赖性的信息系统安全投资及协调机制

考虑信息系统安全相互依赖情形下最优化信息系统连续时间安全投资水平是一个值得研究的问题。首先讨论了非合作博弈下信息系统安全投资的最优策略选择,在此基础上讨论了安全投资效率参数、黑客学习能力、传染风险对信息系统脆弱性及信息系统安全投资率的影响。其次,在推导出两企业在合作博弈情形下最优策略选择的基础上,对比两种情形下的博弈均衡结果,得出合作博弈下的投资水平高于非合作博弈下的投资水平。原因是两个企业的相互依赖关系隐含着企业投资的负外部性,从而导致企业投资不足。最后,构建一种双边支付激励机制消除企业投资不足问题,从而使企业达到合作博弈下的最优投资水平,提高两个企业的收益。     

Variational convergence of bivariate functions: lopsided convergence

We explore convergence notions for bivariate functions that yield convergence and stability results for their maxinf (or minsup) points. This lays the foundations for the study of the stability of solutions to variational inequalities, the solutions of inclusions, of Nash equilibrium points of non-cooperative games and Walras economic equilibrium points, of fixed points, of solutions to inclusions, the primal and dual solutions of convex optimization problems and of zero-sum games. These applications will be dealt with in a couple of accompanying papers.     

Characterization of the existence of a pure-strategy Nash equilibrium

In this work, we provide a necessary and sufficient condition for the existence of a pure-strategy Nash equilibrium for non-cooperative games in topological spaces.     

Student achievement effects of technology-supported remediation of understanding of fractions

Students have difficulty learning fractions, and problems in understanding fractions persist into adulthood, with moderate to severe consequences for everyday and occupational decision-making. Remediation of student misconceptions is hampered by deficiencies in teachers’ knowledge of the discipline and pedagogical content knowledge. We theorized that a technology resource could provide the sequencing and scaffolding that teachers might have difficulty providing. Five sets of learning objects, called CLIPS (Critical Learning Instructional Paths Supports), were developed to provide remediation on fraction concepts. In this article, we describe one stage in a research program to develop, implement and evaluate CLIPS. Two studies were conducted. In Study 1, 14 grade 7–10 classrooms were randomly assigned, within schools, to early and late treatment conditions. A pre-post, delayed treatment design found that CLIPS had no effect on achievement for the Early Treatment group due to unforeseen implementation problems. These hardware and software issues were mitigated in the late treatment in which CLIPS contributed to student achievement (Cohen's d = 0.30). Study 2 was a pre-post, single group replication involving 18 grade 7 classrooms. The independent variable was the number of CLIPS completed. Completion of all five CLIPS contributed to higher student achievement: Cohen's d = 0.53, compared to students who completed none (d = 0.00) or 1–4 CLIPS (d = 0.02). The two studies indicate that a research-based set of learning objects is effective when the full program is implemented. Incomplete sequences deprive students of instruction in one or more constructs linked to other key ideas in the conceptual map and reduce the amount of practice required to remediate student misconceptions.     

The design of a Tort law to control accidents

In this paper we analyse a two-stage game involving the government and n agents who engage in a single activity (driving). The government establishes the legal policy setting and the agents proceed to play a non-cooperative game of incomplete information with a risk of accident in which their behavioral strategy is their level of care. We examine the Nash-equilibrium conditions for single-activity accidents between heterogeneous agents, ‘good’ drivers or ‘bad’ drivers allowing a variable damage function and a liability rule defined on the cube. The relative desirability for society of alternative equilibria and the conditions under which they can obtain are discussed. The constraints which circumscribe the ability of the government to induce an equilibrium involving careful driving are demonstrated. It transpires that when the proportion of good drivers increases, it becomes more difficult to sustain a careful equilibrium whereas an equilibrium of reckless behavior becomes easier to sustain. Various extensions of the models are also presented.     

Productive and ineffective efforts: how student effort in high school mathematics relates to college calculus success

Relativizing the popular belief that student effort is the key to success, this article finds that effort in the most advanced mathematics course in US high schools is not consistently associated with college calculus performance. We distinguish two types of student effort: productive and ineffective efforts. Whereas the former carries the commonly expected benefits, the latter is associated with negative consequences. Time spent reading the course text in US high schools was negatively related to college calculus performance. Daily study time, however, was found to be either a productive or an ineffective effort, depending on the level of high school mathematics course and the student's performance in it.