Solving parity games through fictitious play

The thesis aims to find an efficient algorithm for solving parity games. Parity games are graph-based, 0-sum, 2-person games with infinite plays. It is known that these games are determined: all nodes in these games are won by exactly one player. Solving parity games is equivalent to the model checking problem of modal mu-calculus; an efficient solution has important implications to program verification and controller synthesis. Although the decision problem of which player wins a given node is generally believed to be in PTIME, all known algorithms so far have been shown to run in (sub)exponential time. The design of existing algorithms either derives from the determinacy proof of parity games or from a purely graph theoretical perspective, using certain rank functions to iteratively search for an optimal solution. Since parity games are 2-person, 0-sum games, in this thesis I borrow ideas of game theory and investigate the viability of using fictitious play to solve them. Fictitious play is a method where two players choose strategies in strict alternation, and where these choices are “best responses” against the last k (so called bounded recall length) or against all strategies (unbounded recall length) of the other player chosen so far. I use this method to design an algorithm that can solve partity games and study its theoretical and experimental properties. For example, I prove that the basic algorithm solves fully connected games in polynomial time through a number of iterations that is bounded by a small constant. Although the proof is not extended to the general cases in the thesis, the basic algorithm performs demonstrably well against existing solvers in experiments over a large number and variety of games. In particular, the empirically obtained number of iterations that our basic algorithm requires appears to increase polynomially against the game sizes for all the games tested. Furthermore, the algorithm is conjectured to have a run time complexity bounded by O(n4 log2(n)) and I provide a discussion of strategy graphs and their emperically observed properties that motivates this conjecture. One caveat of fictitious play with bounded recall length is that the algorithm may fail to converge to the optimal solution due to the presence of nonoptimal strategy cycles of length greater than 2. In this thesis, I observe that in practice such cases account for less than 0.01% of the games tested. Different cycle resolution methods are explored in the thesis to address this. One particular method combines our basic algorithm and the discrete strategy solver together such that the resulting algorithm is guaranteed to terminate with the optimal solution. Also, this combined solver shares the runtime performance of fictitious play.Open Acces

Applying Expressive Arts Therapy Interventions with Chinese Adolescents with Academic Maladjustment

This thesis first explores the relationship between several concepts related to academic stress (academic burnout, academic weariness or school weariness, and school refusal) and their influencing factors, which are collectively referred to as academic maladjustment. It then reviews the empirical intervention research on academic maladjustment among Chinese adolescents. Study review has found that effective talk therapy interventions for Chinese adolescents with academic maladjustment often adopt a systematic perspective of family therapy and related techniques. Researchers worked with adolescents on their personal factors that contribute to academic maladjustment and work on the interpersonal level and obtained the cooperation of parents and teachers who were closely related to adolescents\u27 academic adjustment, which was seldom discussed by creative arts therapy. In the end, this thesis puts forward the conceptions on utilizing the methods of focus-oriented expressive arts therapy from the perspective of brief family therapy in a problem-solving approach to intervening Chinese adolescents with academic maladjustment and suggests future study to use Expressive Therapies Continuum to help academic maladjustment adolescents\u27 family

Chinese-Style Of Reward-Based Crowd-Funding: Financial Approaches Or Marketing Tools?

Crowd-funding is an emerging industry in China. However, Chinese crowd-funding market has some different characteristics to its US-based or Europe-based predecessors. Some of Chinese founders regard reward-based crowd-funding as a funding approach, while others highlight its marketing functions. Thus, which play more important role at present? This paper investigates the reason for the special performance of reward-based crowd-funding in China from multiple perspectives. The results indicate that the special institutional environments of China---lack of perfect social credit systems and legal systems, not granting legal definition and status for crowd-funding, leads to an inevitable result that Chinese founders make heavy use of the marketing functions of crowd-funding but make light use of the funding function at the present stage. With the perfecting of the institutional and legal environment, many small-and-medium-enterprises and individual entrepreneurs are expected to pay more attention on the funding function of crowd-funding than today

A workbench for preprocessor design and evaluation: toward benchmarks for parity games

We describe a prototype workbench for the study of parity games and their solvers. This workbench is aimed at facilitating two activities: to aid in the design, validation, and evaluation of preprocessors for parity game solvers; and to aid in the generation of benchmark parity games that are meaningful for a wide range of solvers. Our workbench allows for easy composition of preprocessors, can populate databases with games and their meta-data, offers a query language for generating games of interest, and has already found potentially hard games

Modification Strategies of Titanium Dioxide

Titanium dioxide (TiO2) is a standard white pigment. However, when TiO2 is exposed to ultraviolet light, it will catalyze the degradation of the surrounding organic matrix. Surface coating of TiO2 is an effective method for reducing the catalytic effect of TiO2. It can also improve the dispersion of TiO2 in an organic matrix. This review critically introduces recent results on the surface coating of TiO2. First, the main features of TiO2, including processes, structure, and final properties, are described briefly. Second, this chapter reports and discusses different surface coating methods for TiO2 with inorganic oxides and organic matter. Inorganic oxides, such as Al2O3, SiO2, and ZrO2, would form a continuous dense film and block the defects of the TiO2 lattice. They can give TiO2 excellent weather resistance. The organic matter available for surface treatment includes the surfactant, the coupling agent, and the macromolecule. They can improve the affinity of TiO2 with various organic matrices. Surfactant treatment is relatively simple. Coupling agents can give TiO2 more novel properties, such as thermal stability. Macromolecules can increase the volume of TiO2 particles through steric hindrance and improve the dispersion of TiO2 in an organic matrix. However, coating TiO2 in a single matter is challenging to meet the increasing performance requirements. Therefore, it is necessary to study further the effect of co-coating with different inorganic oxides and organic matter on the structure and properties of TiO2

Economic feasibility analysis of choices for not connected clients: photovoltaic off-grid systems, compared to grid based system

Off-grid photovoltaic systems are less constrained by national regulations than their grid-connected counterparts. Off-grid systems do not depend on feed-in tariff and the analysis of their cost-efficiency is more stable along time. This work calculates the economic parameters for two different technologies of photovoltaic systems and compares the levelized cost of electricity (LCOE), with the price of the electricity, including the cost for the connection of the system related to the distance to the grid. The results show that the sustained decline in photovoltaic module¿s price contributes to subsequent decline in LCOE, whereas the increase in the price of grid electricity and materials related to the connection makes off-grid systems more cost-effective for remote areas. Finally, to determine if the photovoltaic system could be an economic alternative for investments in remote regions, a comparison between the cost of grid extension and the LCOE of a high capacity photovoltaic system was undertaken

HR-Pro: Point-supervised Temporal Action Localization via Hierarchical Reliability Propagation

Point-supervised Temporal Action Localization (PSTAL) is an emerging research direction for label-efficient learning. However, current methods mainly focus on optimizing the network either at the snippet-level or the instance-level, neglecting the inherent reliability of point annotations at both levels. In this paper, we propose a Hierarchical Reliability Propagation (HR-Pro) framework, which consists of two reliability-aware stages: Snippet-level Discrimination Learning and Instance-level Completeness Learning, both stages explore the efficient propagation of high-confidence cues in point annotations. For snippet-level learning, we introduce an online-updated memory to store reliable snippet prototypes for each class. We then employ a Reliability-aware Attention Block to capture both intra-video and inter-video dependencies of snippets, resulting in more discriminative and robust snippet representation. For instance-level learning, we propose a point-based proposal generation approach as a means of connecting snippets and instances, which produces high-confidence proposals for further optimization at the instance level. Through multi-level reliability-aware learning, we obtain more reliable confidence scores and more accurate temporal boundaries of predicted proposals. Our HR-Pro achieves state-of-the-art performance on multiple challenging benchmarks, including an impressive average mAP of 60.3% on THUMOS14. Notably, our HR-Pro largely surpasses all previous point-supervised methods, and even outperforms several competitive fully supervised methods. Code will be available at https://github.com/pipixin321/HR-Pro.Comment: 12 pages, 8 figure

Analysis of air mass dependence of three photovoltaic arrays

The solar spectrum, which is also could be described by air mass factor, has a significant relationship with the performance of photovoltaic modules. The air mass dependence has been investigated by a theoretical method as well as an actual case of three different photovoltaic arrays: polycrystalline silicon, amorphous silicon and cadmium telluride, at the EUIT Agrícola-UPM (Madrid, Spain, 40.4426oN, 3.7295oW). The calculating results show that: AM dependence of poly-Si array is positive because an elevating AM-value indicates a red shift and poly-Si module is more red sensitive; On the contrary, as a-Si module and CdTe module are more blue sensitive, their AM dependences are negative. Furthermore, the outdoor AM dependences of three arrays are corresponding to the calculating results although the thermal annealing effect could be superimposed on spectral effect in the case of a-Si. Keywords: PV system, spectral response, polycrystalline silicon, a-Si, CdT