Compass Constructions
  The purpose of this short manuscript is to show that all point constructions that can be done via ruler and compass, can also be done with compass exclusively. If we are using compass and ruler the way we construct new points is by first constructing circles or lines and then considering their intersection. This hints us a way to approach the problem, which is possibly the most straightforward approach. However, the execution of it is rather interesting and worth the effort. The approach that we are talking about is to show that the intersection of circles and lines, lines and lines can be constructed using only compass. The intersection of two circle comes in as trivial given, since all we need to do is construct circles in this situation. Our task can be formulated even more precisely. Suppose we are given four points A, B, C and D. Our task is to show that the intersection of lines AB and CD can be constructed using only compass, and that the intersection of AB and the circle centered C and passing through D can be also constructed using compass. 
Arman Margaryan and Nerses Aramian
math.HO