Jorgensen's picture of quasifuchsian punctured torus groups

In [40, Theorems 3.1, 3.2 and 3.3], Jorgensen describes the combinatorial structure of the Ford domain of a quasifuchsian punctured torus group. It was very difficult for the authors to get a conceptual understanding of the statement, because it consists of nine assertions, each of which describes some property of the Ford domain, and it does not explicitly present a topological or combinatorial model of the Ford domain. In this chapter, we construct an explicit model of the Ford domain, and reformulate Jorgensen's theorem in terms of the model. In short, we present a 3-dimensional picture to Jorgensen's theorem. We note that this chapter is essentially equal to the announcement [10].