Efficient Timeout Synthesis in Fixed-Delay CTMC Using Policy Iteration
| Autor: | Vojtech Rehak, L'uboš Korenčiak, Antonín Kučera |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Computer Science - Logic in Computer Science
Polynomial Mathematical optimization Computer Science - Performance Speedup Markov chain Computer science Univariate Markov process 020207 software engineering 02 engineering and technology Set (abstract data type) symbols.namesake Mathematical software 0202 electrical engineering electronic engineering information engineering symbols 020201 artificial intelligence & image processing Markov decision process Algorithm |
| Zdroj: | MASCOTS |
| DOI: | 10.1109/mascots.2016.34 |
| Popis: | We consider the fixed-delay synthesis problem for continuous-time Markov chains extended with fixed-delay transitions (fdCTMC). The goal is to synthesize concrete values of the fixed-delays (timeouts) that minimize the expected total cost incurred before reaching a given set of target states. The same problem has been considered and solved in previous works by computing an optimal policy in a certain discrete-time Markov decision process (MDP) with a huge number of actions that correspond to suitably discretized values of the timeouts. In this paper, we design a symbolic fixed-delay synthesis algorithm which avoids the explicit construction of large action spaces. Instead, the algorithm computes a small sets of "promising" candidate actions on demand. The candidate actions are selected by minimizing a certain objective function by computing its symbolic derivative and extracting a univariate polynomial whose roots are precisely the points where the derivative takes zero value. Since roots of high degree univariate polynomials can be isolated very efficiently using modern mathematical software, we achieve not only drastic memory savings but also speedup by three orders of magnitude compared to the previous methods. Comment: This article is a full version of a paper published at Modeling, Analysis, and Simulation On Computer and Telecommunication Systems (MASCOTS) 2016 conference |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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