By "in some sense", do you mean it can be parallelized to O(1) time as long as you don't have to actually build up the data structures that result from partitio

By "in some sense", do you mean it can be parallelized to O(1) time as long as you don't have to actually build up the data structures that result from partitioning (e.g. arrays)? Then it's not clear to me why this assumption is applicable to quicksorting an array. Doesn't it call for some non-obvious representation of intermediate results?