AC-3

AC-3 (Arc Consistency Algorithm 3) is a method used in solving constraint satisfaction problems—like scheduling or puzzles—by reducing possible options for each variable. It examines pairs of variables and removes values that can't possibly work together, ensuring that every remaining value has at least one compatible pair. This process continues until all values are consistent or no more removals are possible. AC-3 helps streamline solutions by narrowing down choices early, making it easier and faster to find a valid overall solution.