Algorithm Portfolio for Individual-based Surrogate-Assisted Evolutionary Algorithms

Surrogate-assisted evolutionary algorithms (SAEAs) are powerful optimisation tools for computationally expensive problems (CEPs). However, a randomly selected algorithm may fail in solving unknown problems due to no free lunch theorems, and it will cause more computational resource if we re-run the algorithm or try other algorithms to get a much solution, which is more serious in CEPs. In this paper, we consider an algorithm portfolio for SAEAs to reduce the risk of choosing an inappropriate algorithm for CEPs. We propose two portfolio frameworks for very expensive problems in which the maximal number of fitness evaluations is only 5 times of the problem's dimension. One framework named Par-IBSAEA runs all algorithm candidates in parallel and a more sophisticated framework named UCB-IBSAEA employs the Upper Confidence Bound (UCB) policy from reinforcement learning to help select the most appropriate algorithm at each iteration. An effective reward definition is proposed for the UCB policy. We consider three state-of-the-art individual-based SAEAs on different problems and compare them to the portfolios built from their instances on several benchmark problems given limited computation budgets. Our experimental studies demonstrate that our proposed portfolio frameworks significantly outperform any single algorithm on the set of benchmark problems

Sequential Design for Ranking Response Surfaces

We propose and analyze sequential design methods for the problem of ranking several response surfaces. Namely, given $L \ge 2$ response surfaces over a continuous input space $\cal X$, the aim is to efficiently find the index of the minimal response across the entire $\cal X$. The response surfaces are not known and have to be noisily sampled one-at-a-time. This setting is motivated by stochastic control applications and requires joint experimental design both in space and response-index dimensions. To generate sequential design heuristics we investigate stepwise uncertainty reduction approaches, as well as sampling based on posterior classification complexity. We also make connections between our continuous-input formulation and the discrete framework of pure regret in multi-armed bandits. To model the response surfaces we utilize kriging surrogates. Several numerical examples using both synthetic data and an epidemics control problem are provided to illustrate our approach and the efficacy of respective adaptive designs.Comment: 26 pages, 7 figures (updated several sections and figures

Risk and Uncertainty in Environmental Economics: From Theory to Policy

A lack of awareness and understanding of risk and uncertainty can lead to poor decision making and higher costs for policy providers, as not accounting for them may produce policy which is inflexible and with a negative effect on welfare. Further, misunderstanding of and/or failure to account for risk and uncertainty can inhibit research and development for policy to which environmental economics can contribute (for example, in developing effective measures of sustainability). The aim of this project is to develop guidelines for ‘Best Practice’ approaches to risk and uncertainty in environmental economics for guiding policy development and implementation, taking into account key issues such as costs, irreversibility, adaptation and dynamics. These guidelines are developed by examining the frameworks commonly used by environmental economists to account for risk and uncertainty (such as the Precautionary Principle and Cost Benefit Analysis) as well as specifically developed theories (e.g. Quiggin’s Rank Dependent Utility Theory), borrowing from other disciplines (e.g. Prospect Theory) and drawing attention to lesser known ideas (e.g. Shackle’s Model).Environmental Economics and Policy,

Kemahiran menggunakan peralatan dan perisian dalam menghasilkan produk ukur : satu tinjauan ke atas pelajar diploma ukur tanah di Politeknik Sultan Haji Ahmad Shah, Kuantan, Pahang

Projek ini adalah untuk melihat kemahiran yang diperlukan oleh pelajar Diploma Ukur Tanah dalam menggunakan peralatan ukur dan perisian berkaitan. Sampel kajian terdiri daripada 32 orang pelajar semester keenam yang sedang mengikuti kursus Diploma Ukur Tanah di Politeknik Sultan Haji Ahamd Shah, Kuantan Pahang. Perolehan data adalah melalui borang soal selidik. Pengkaji memberi tumpuan kepada persoalan kajian yang melihat kepada tiga aspek iaitu, jenis-jenis peralatan dan perisian ukur tanah di firma ukur tanah, aspek kemahiran-kemahiran yang dimiliki pelajar meliputi kemahiran menggunakan peralatan ukur, kemahiran menggunakan perisian ukur dan kemahiran-kemahiran asas meliputi teori yang diperlukan dalam keija-keija ukur dan dalam menghasilan produk uk ur. Dapatan kajian menunjukkan pelajar mahir menggunakan alat ukur manual dan kemahiran pelajar terhadap penggunaan perisian adalah tidak pelbagai. Hasil kajian juga menunjukkan bahawa pelajar mahir dalam mengaplikasikan teori-teori yang digunakan dalam keija ukur dan penghasilan produk ukur