Aydoğan, ReyhanFujita, K.Baarslag, T.Jonker, C. M.Ito, T.Ohsawa, Y.Yada, K.Ito, T.Takama, Y.Sato-Shimokawara, E.Abe, A.Mori, J.Matsumura, N.Matsumura, N.2021-10-122021-10-122020978-303039877-42194-5357http://hdl.handle.net/10679/7635https://doi.org/10.1007/978-3-030-39878-1_8This is an extension from a selected paper from JSAI2019. There are a number of research challenges in the field of Automated Negotiation. The Ninth International Automated Negotiating Agent Competition encourages participants to develop effective negotiating agents, which can negotiate with multiple opponents more than once. This paper discusses research challenges for such negotiations as well as presenting the competition set-up and results. The results show that winner agents mostly adopt hybrid bidding strategies that take their opponents’ preferences as well as their strategy into account.engrestrictedAccessconferenceObject1128778910.1007/978-3-030-39878-1_8Multi-agent systemNegotiationCompetition2-s2.0-85080943591