“…Considering the limited number of users' interactions in CRS, we set ๐ to {5, 10, 20}, respectively. There are several schemes to split ๐ into ๐ 1 and ๐ 2 , we choose the greedy search method (e.g., when ๐ = 5, (๐ 1 , ๐ 2 ) could be (1, 4), (2, 3), (3,2) or (4, 1)) to nd the optimal splitting scheme. Note that we set neither ๐ 1 nor ๐ 2 to 0 in this section, where 0 denotes that either the LQS subsession or the GQS subsession is removed, which we will discuss later in ยง 6.4.…”