{"day":"01","has_accepted_license":"1","publist_id":"3938","tmp":{"legal_code_url":"https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode","image":"/images/cc_by_nc_nd.png","name":"Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)","short":"CC BY-NC-ND (4.0)"},"oa_version":"Published Version","article_type":"original","department":[{"_id":"KrCh"},{"_id":"ToHe"}],"author":[{"id":"2E5DCA20-F248-11E8-B48F-1D18A9856A87","first_name":"Krishnendu","orcid":"0000-0002-4561-241X","full_name":"Chatterjee, Krishnendu","last_name":"Chatterjee"},{"first_name":"Luca","last_name":"De Alfaro","full_name":"De Alfaro, Luca"},{"last_name":"Henzinger","full_name":"Henzinger, Thomas A","first_name":"Thomas A","orcid":"0000−0002−2985−7724","id":"40876CD8-F248-11E8-B48F-1D18A9856A87"}],"ec_funded":1,"corr_author":"1","fulldoi":"https://doi.org/10.1016/j.jcss.2012.12.001","month":"08","project":[{"name":"Quantitative Graph Games: Theory and Applications","call_identifier":"FP7","_id":"2581B60A-B435-11E9-9278-68D0E5697425","grant_number":"279307"},{"grant_number":"S11407","call_identifier":"FWF","name":"Game Theory","_id":"25863FF4-B435-11E9-9278-68D0E5697425"},{"_id":"2587B514-B435-11E9-9278-68D0E5697425","name":"Microsoft Research Faculty Fellowship"}],"abstract":[{"text":"We consider concurrent games played on graphs. At every round of a game, each player simultaneously and independently selects a move; the moves jointly determine the transition to a successor state. Two basic objectives are the safety objective to stay forever in a given set of states, and its dual, the reachability objective to reach a given set of states. First, we present a simple proof of the fact that in concurrent reachability games, for all ε&gt;0, memoryless ε-optimal strategies exist. A memoryless strategy is independent of the history of plays, and an ε-optimal strategy achieves the objective with probability within ε of the value of the game. In contrast to previous proofs of this fact, our proof is more elementary and more combinatorial. Second, we present a strategy-improvement (a.k.a. policy-iteration) algorithm for concurrent games with reachability objectives. Finally, we present a strategy-improvement algorithm for turn-based stochastic games (where each player selects moves in turns) with safety objectives. Our algorithms yield sequences of player-1 strategies which ensure probabilities of winning that converge monotonically (from below) to the value of the game. © 2012 Elsevier Inc.","lang":"eng"}],"article_processing_charge":"No","year":"2013","publisher":"Elsevier","publication_status":"published","pubrep_id":"388","date_published":"2013-08-01T00:00:00Z","status":"public","file_date_updated":"2020-07-14T12:45:51Z","type":"journal_article","user_id":"317138e5-6ab7-11ef-aa6d-ffef3953e345","oa":1,"title":"Strategy improvement for concurrent reachability and turn based stochastic safety games","license":"https://creativecommons.org/licenses/by-nc-nd/4.0/","scopus_import":"1","date_updated":"2025-09-29T13:40:38Z","publication":"Journal of Computer and System Sciences","file":[{"creator":"system","checksum":"6d3ee12cceb946a0abe69594b6a22409","date_updated":"2020-07-14T12:45:51Z","file_id":"5370","file_size":425488,"relation":"main_file","file_name":"IST-2015-388-v1+1_1-s2.0-S0022000012001778-main.pdf","content_type":"application/pdf","date_created":"2018-12-12T10:18:48Z","access_level":"open_access"}],"citation":{"mla":"Chatterjee, Krishnendu, et al. “Strategy Improvement for Concurrent Reachability and Turn Based Stochastic Safety Games.” <i>Journal of Computer and System Sciences</i>, vol. 79, no. 5, Elsevier, 2013, pp. 640–57, doi:<a href=\"https://doi.org/10.1016/j.jcss.2012.12.001\">10.1016/j.jcss.2012.12.001</a>.","ieee":"K. Chatterjee, L. De Alfaro, and T. A. Henzinger, “Strategy improvement for concurrent reachability and turn based stochastic safety games,” <i>Journal of Computer and System Sciences</i>, vol. 79, no. 5. Elsevier, pp. 640–657, 2013.","ista":"Chatterjee K, De Alfaro L, Henzinger TA. 2013. Strategy improvement for concurrent reachability and turn based stochastic safety games. Journal of Computer and System Sciences. 79(5), 640–657.","short":"K. Chatterjee, L. De Alfaro, T.A. Henzinger, Journal of Computer and System Sciences 79 (2013) 640–657.","apa":"Chatterjee, K., De Alfaro, L., &#38; Henzinger, T. A. (2013). Strategy improvement for concurrent reachability and turn based stochastic safety games. <i>Journal of Computer and System Sciences</i>. Elsevier. <a href=\"https://doi.org/10.1016/j.jcss.2012.12.001\">https://doi.org/10.1016/j.jcss.2012.12.001</a>","chicago":"Chatterjee, Krishnendu, Luca De Alfaro, and Thomas A Henzinger. “Strategy Improvement for Concurrent Reachability and Turn Based Stochastic Safety Games.” <i>Journal of Computer and System Sciences</i>. Elsevier, 2013. <a href=\"https://doi.org/10.1016/j.jcss.2012.12.001\">https://doi.org/10.1016/j.jcss.2012.12.001</a>.","ama":"Chatterjee K, De Alfaro L, Henzinger TA. Strategy improvement for concurrent reachability and turn based stochastic safety games. <i>Journal of Computer and System Sciences</i>. 2013;79(5):640-657. doi:<a href=\"https://doi.org/10.1016/j.jcss.2012.12.001\">10.1016/j.jcss.2012.12.001</a>"},"volume":79,"_id":"2854","page":"640 - 657","acknowledgement":"This work was partially supported in part by the NSF grants CCR-0132780, CNS-0720884, CCR-0225610, by the Swiss National Science Foundation, ERC Start Grant Graph Games (Project No. 279307), FWF NFN Grant S11407-N23 (RiSE), and a Microsoft faculty fellows","date_created":"2018-12-11T11:59:57Z","quality_controlled":"1","external_id":{"isi":["000316837300011"]},"issue":"5","ddc":["000"],"intvolume":"        79","isi":1,"language":[{"iso":"eng"}],"doi":"10.1016/j.jcss.2012.12.001"}