A saturation method for the modal μ-calculus over pushdown systems

We present an algorithm for computing directly the denotation of a μ-calculus formula χ over the configuration graph of a pushdown system. Our method gives the first extension of the saturation technique to the full μ-calculus. Finite word automata are used to represent sets of pushdown configurations. Starting from an initial automaton, we perform a series of automaton manipulations which compute the denotation by recursion over the structure of the formula. We introduce notions of under-approximation (soundness) and over-approximation (completeness) that apply to automaton transitions rather than runs. Our algorithm is relatively simple and direct, and avoids an immediate exponential blow up. Finally, we show experimentally that the direct algorithm is more efficient than via a reduction to parity games.     

Soft-constrained stochastic Nash games for weakly coupled large-scale systems

In this paper, we discuss infinite-horizon soft-constrained stochastic Nash games involving state-dependent noise in weakly coupled large-scale systems. First, we formulate linear quadratic differential games in which robustness is attained against model uncertainty. It is noteworthy that this is the first time conditions for the existence of robust equilibria have been derived based on the solutions of sets of cross-coupled stochastic algebraic Riccati equations (CSAREs). After establishing an asymptotic structure with positive definiteness for CSAREs solutions, we derive a recursive algorithm by means of Newton’s method so that it can be used to obtain solutions for CSAREs. As another important feature, we propose a high-order approximate Nash strategy based on iterative solutions. Finally, we provide a numerical example to verify the efficiency of the proposed algorithms.     

An iterative adaptive dynamic programming method for solving a class of nonlinear zero-sum differential games

In this paper, a new iterative adaptive dynamic programming (ADP) method is proposed to solve a class of continuous-time nonlinear two-person zero-sum differential games. The idea is to use the ADP technique to obtain the optimal control pair iteratively which makes the performance index function reach the saddle point of the zero-sum differential games. If the saddle point does not exist, the mixed optimal control pair is obtained to make the performance index function reach the mixed optimum. Stability analysis of the nonlinear systems is presented and the convergence property of the performance index function is also proved. Two simulation examples are given to illustrate the performance of the proposed method.     

UCT-RAVE算法在多人非完备信息博弈中的应用

针对传统博弈搜索算法无法适用于多人非完备信息博弈,通过分析UCT-RAVE算法的原理和特性,提出了运用UCT-RAVE算法与蒙特卡罗抽样技术相结合的方法.通过蒙特卡罗抽样技术将非完备信息提取为有一定可信度的完备信息,运用UCT-RAVE算法基于此完备信息进行搜索,结合多次蒙特卡罗抽样下的最佳收益,选择最适行动.实例结果表明了该方法的可行性和有效性.     

Stepping out of the Magic Circle: Regulation of Play/Life Boundary in MMO‐Mediated Romantic Relationship

Massively multiplayer online role‐playing games (MMOs) are spaces of socialization and relationship formation and maintenance. This qualitative study seeks to understand how MMO players delineate the boundary between play and life when it comes to their game‐originated romance. A typology of players was devised to understand players' constructions of boundaries, and players' strategies against perceived stigma when moving their relationship offline were discussed. The findings call for a shift towards a more player‐centric and pluralist conceptualization of the magic circle of play.     

Finding the nucleolus of any n-person cooperative game by a single linear program

In this paper we show a new method for calculating the nucleolus by solving a unique minimization linear program with O(4ⁿ)$O(4^n)$ constraints whose coefficients belong to {−1,0,1}$\{-1,0,1\}$. We discuss the need of having all these constraints and empirically prove that they can be reduced to O(_kmax2ⁿ)$O(k_{\mathit{max}}{2}^n)$, where k_max is a positive integer comparable with the number of players. A computational experience shows the applicability of our method over (pseudo)random transferable utility cooperative games with up to 18 players.     

Why do not satisfied consumers show reuse behavior? The context of online games

Empirical studies have consistently identified consumer satisfaction as a key antecedent to reuse behavior. Business has focused on consumer satisfaction as a way to improve consumer loyalty. However, it remains unknown why there are so many satisfied consumers who do not show reuse behavior. Therefore, the present study examined the potential factors moderating the association between consumer satisfaction and reuse behavior. A literature review and focus groups were used to explore moderating variables, and hierarchical regression analysis was used to test their influence. Results from a study of 490 online gamers in Taiwan showed that the relationship between consumer satisfaction and reuse behavior is contingent upon the moderating effects of customer involvement and perceived specific/upgrading activities. In particular, the relationship between consumer satisfaction and reuse behavior is more sensitive when customer involvement is lower.     

Computing, Social Activity, and Entertainment: A Field Study of a Game MUD

Are game and entertainment systems different than work-oriented systems? What drives the user's experience in a collaborative game? To answer these questions, we performed a participant-observation study of a combat MUD, a game similar to Dungeons and Dragons. Our interest is in how this social world is arranged and managed (rather than, for example, in how participants form or display individual identities). The study explores the social arrangements and activities that give meaning and structure to the participants. We found that conflict and cooperation were the dominant social activities on this MUD, much more so than sociability. The game's management played a critical function in maintaining and promoting these activities. Moreover, novelty and entertainment were important for the design of both the system features and the sociality itself.     

A uniqueness result for the isaacs equation corresponding to nonlinear H∞ control

The dynamic programming equation (DPE) corresponding to nonlinear H_∞ control is considered. When the cost grows quadratically in the state, it is well known that there may be an infinite number of viscosity solutions to the DPE. In fact, there may be more than one classical solution when a classical solution exists. For the case of fixed feedback control, it is shown that there exists a unique viscosity solution in the class of solutions meeting a certain growth condition, and a representation in terms of available storage is obtained. For the active control case, where the H_∞ problem is represented by a differential game, a similar representation result is obtained under the assumption of existence of a suboptimal feedback control. This research was partially supported by AFOSR under Grant F49620-95-1-0296 and by ONR under Grant N0014-96-1-0267.     

参数不确定非线性系统的自适应控制和鲁棒控制

研究一类参数不确定非线性系统的非自适应鲁棒控制及自适应控制问题。通过引入二人零和对策得到非自适应鲁棒控制律，并与参数估计结合得到自适应控制律。证明了参数估计有界和收敛时闭环系统Ｌｙａｐｕｎｏｖ稳定性和渐近稳定性。仿真结果说明了该方法的有效性及具体实现方法。