Commutativity

• Do you know what commutativity in arithmetic is?
• ((A+B)+C) = (A + (B + C))
• In general it means that it doesn't matter what order you apply the operators in.
• If the problem is like this, it's usually a lot easier to solve.
• Is Sudoku commutative.Yes.
• In fact all CSPs are (pg 270). The only thing you can really do (as oppose to decide what to do) is assign a variable.
• It doesn't matter in what order you assign variables.