“…Later on, many works discover the optimal regular estimate of Boltzmann collision operator in v in different setting. We refer to [2,9,11,24,31] for the dissipation estimate of collision operator, and [3,7,8,10,12,13,[18][19][20][25][26][27] for smoothing effect of the solution to Boltzmann equation in different aspect. These works show that the Boltzmann operator behaves locally like a fractional operator:…”