• The length of the sequence has a upper bound because AR has better performance when the size of sequence is relatively small (detailed discussion can be found in Section E of SI). In this work, we set this upper bound to be 10 so that the the 'batch' sequence will be {e Tp |p = 1, 2, .., κ, κ ≤ 10 ∧ f loor(lgI κ+1 ) < f loor(lgI 1 )}.