 The alternative name SARSA, proposed by Rich Sutton, was only mentioned as a footnote.This name simply reflects the fact that the main function for updating the Q-value depends on the current state of the agent "S1", the action the agent chooses "A1", the reward "R" the agent gets for choosing this action, the state "S2" that the agent enters after taking that action, and finally the next action "A2" the agent chooses in its new state.The acronym for the quintuple (st, at, rt, st+1, at+1) is SARSA.