We introduce a simple sequence model inspired by control systems thatgeneralizes these approaches while addressing their shortcomings.

Between 2018 and 2020, the field witnessed asurgein the development of these models (Devlin etal.,2019;Liu

However,such assumption does not always hold inreality. Itisoften the case that arm pulls are performed by multiple different agents whose individual goals are not aligned with the system, and the principal can only observeagents' actions. One typical example is the individual buyers (agents) and the online shopping platform (the principal).

For (see 6 fordetails), densityestimation6, 8, 53].