An engineering change fixes one line in the arbiter and the netlist is rebuilt overnight. Simulation of the fixed scenario passes, but nobody checks whether the fix altered any other grant pattern. Equivalence checking answers both halves: the revised block differs exactly where the fix intended, and agrees everywhere else. This topic runs that flow on the round-robin arbiter and closes with the honest limit of the method.

Suggested order: top to bottom. The ECO flow is the daily-use pattern; the twin-arbiter lesson is its hardest workout; the last lesson states the limit that keeps the method honest. For the synthesis-side ECO flow see Proving an ECO.