TY - GEN
T1 - Winning a tournament by any means necessary
AU - Gupta, Sushmita
AU - Roy, Sanjukta
AU - Saurabh, Saket
AU - Zehavi, Meirav
N1 - Publisher Copyright:
© 2018 International Joint Conferences on Artificial Intelligence. All right reserved.
PY - 2018/1/1
Y1 - 2018/1/1
N2 - In a tournament, n players enter the competition. In each round, they are paired-up to compete against each other. Losers are thrown, while winners proceed to the next round, until only one player (the winner) is left. Given a prediction of the outcome, for every pair of players, of a match between them (modeled by a digraph D), the competitive nature of a tournament makes it attractive for manipulators. In the Tournament Fixing (TF) problem, the goal is to decide if we can conduct the competition (by controlling how players are paired-up) so that our favorite player w wins. A common form of manipulation is to bribe players to alter the outcome of matches. Kim and Williams [IJCAI 2015] integrated such deceit into TF, and showed that the resulting problem is NP-hard when ` < (1 − ) log n alterations are possible (for any fixed > 0). For this problem, our contribution is fourfold. First, we present two operations that “obfuscate deceit”: given one solution, they produce another solution. Second, we present a combinatorial result, stating that there is always a solution with all reversals incident to w and “elite players”. Third, we give a closed formula for the case where D is a DAG. Finally, we present exact exponential-time and parameterized algorithms for the general case.
AB - In a tournament, n players enter the competition. In each round, they are paired-up to compete against each other. Losers are thrown, while winners proceed to the next round, until only one player (the winner) is left. Given a prediction of the outcome, for every pair of players, of a match between them (modeled by a digraph D), the competitive nature of a tournament makes it attractive for manipulators. In the Tournament Fixing (TF) problem, the goal is to decide if we can conduct the competition (by controlling how players are paired-up) so that our favorite player w wins. A common form of manipulation is to bribe players to alter the outcome of matches. Kim and Williams [IJCAI 2015] integrated such deceit into TF, and showed that the resulting problem is NP-hard when ` < (1 − ) log n alterations are possible (for any fixed > 0). For this problem, our contribution is fourfold. First, we present two operations that “obfuscate deceit”: given one solution, they produce another solution. Second, we present a combinatorial result, stating that there is always a solution with all reversals incident to w and “elite players”. Third, we give a closed formula for the case where D is a DAG. Finally, we present exact exponential-time and parameterized algorithms for the general case.
UR - http://www.scopus.com/inward/record.url?scp=85055703698&partnerID=8YFLogxK
U2 - 10.24963/ijcai.2018/39
DO - 10.24963/ijcai.2018/39
M3 - Conference contribution
AN - SCOPUS:85055703698
T3 - IJCAI International Joint Conference on Artificial Intelligence
SP - 282
EP - 288
BT - Proceedings of the 27th International Joint Conference on Artificial Intelligence, IJCAI 2018
A2 - Lang, Jerome
PB - International Joint Conferences on Artificial Intelligence
T2 - 27th International Joint Conference on Artificial Intelligence, IJCAI 2018
Y2 - 13 July 2018 through 19 July 2018
ER -