I discovered this book by looking for more information on state charts vs state machines. Harel writing also got me interested in Topology:
"Topological features are a lot more fundamental than geometric ones, in that topology is a more basic branch of mathematics than geometry in terms of symmetries and mappings. One thing being inside another is more basic than it being smaller or larger than the other, or than one being a rectangle and the other a circle. Being connected to something is more basic than being green or yellow or being drawn with a thick line or with a thin line." [1]
