Hi! I have a real problem in understanding the use of symmetry for finding equal potential points in nasty electric circuits. There are lots of problems were the solution simply says: "due to symmetry reasons, nodes X and Y have equal potential", but I rarely really understand the so called symmetry. So far I haven't found someone to properly explain to me how this really works. To better explain myself, I annexed a cubic circuit. The problem asks to find the equivalent resistance when the circuit is connected to a voltage source between points S and A. The values for R1 and R2 are considered known. The solution says that the points I, M and the points H, B are at equal potential, so you can connect them together. Why those points? Bare in mind, this is no homework, just an example (though I would be grateful if anyone would help me understand it). So, can anyone explain me how to find symmetry in similar cases or suggest a paper on this topic?