View source for Exercises:Mond - Topology - 1/Pictures/Q6P1 - 1

[[File:CircleDiagramMondEx1-2016.JPG|thumb|Take -1 to any point on the circle (we pick the south pole in this diagram), then go around the circle clockwise at a constant speed such that by {{M|f(1)}} one has done a full revolution and is back at the starting point.<br/><br/>
The right-hand-side is intended to demonstrate that the interval {{M|(-1,1)}} to the circle without the south-pole is bijective, ie it is injective and surjective, so the diagram on the left is "almost injective" in that it is injective everywhere except that it maps {{M|-1}} and {{M|1}} both to the south pole.<br/>As required]]