A Sharp Upper Bound for Region Unknotting Number of Torus Knots
  Region crossing change for a knot or a proper link is an unknotting operation. In this paper, we provide a sharp upper bound on the region unknotting number for a large class of torus knots and proper links. Also, we discuss conditions on torus links to be proper. 
Vikash Siwach and Madeti Prabhakar
math.GT math.GN