# Constraint Satisfaction

- A constraint satisfaction problem is just what it says, a problem
where constraints must be satisfied.
- A really obvious example of this domain is sudoku.
- In a 9x9 board, each square has to have one of the 9 digits (not
using 0), each row and column have to have each of them, and each
of the 3x3 boxes have to.
- How do you define that problem so that a program can solve that?
- In the sudoku case, you have a partially filled board. You can almost
always reason forward from the current state.
- The structure of the problem is important.
- There are certain techniques that are commonly used.