While doing some questions using Kirchhoff's laws, I came across this problem, as shown in the picture. Obviously, no current passes through the 5 ohm resistor. But then I get confused. 1) If "no current" passed through the branch, wouldn't that be as if the branch weren't there? that would mean that two 1ohm resistors are connected in series and then parallel to each other. However, we could also see the circuit as if the two middle nodes were collapsed together, leaving us with a parallel combination of two 1 ohm resistors on the left and two on the right. This would work, because there is no potential difference across the 5 ohm resistor---but does that mean there isn't any current flow? 2) Take a piece of wire AB (in the picture) for example, there is no potential difference between the two points, but does that mean there is no current flow? Current flow happens only when there is a difference in potential, but the definition of current is Coloumbs per second which has no reference to potential at all... So could someone who's good with definitions help me out? Thank you.