Wiki: "Combinatorics is an area of mathematics primarily concerned with counting, both as a means and an end in obtaining results, and certain properties of finite structures. It is closely related to many other areas of mathematics and has many applications"

Topic   Wiki: Combinatorics      Combinatorics and Probability - a sequence of increasingly more complex situations, each of which is represented by a simple paradigm problem                  The Fusion of Deep Learning and Combinatorics (January 3, 2020)