On Saxe's theorems about the complexity of the Distance Geometry Problem

In 1979, James B.~Saxe published an extended summary on the complexity of the Distance Geometry Problem in the proceedings of the 17th Allerton Conference. Many of the proofs in his paper are sketches, and even the whole proofs do not have all the details. In this paper we provide a commentary to Saxe’s results and hopefully more understandable versions thereof.