Formal Definition of Constraints
A constraint Cijk… involving variables xi, xj, xk …
- is any subset of combinations of values from Di, Dj, Dk …
- I.e. Cijk... ? Di x Dj x Dk …
- indicating the allowed set of values
Most constraint programming languages/toolkits allow a number of ways to write constraints:
- e.g. if D1 = D2 = {1,2,3} …
- { (1,2), (1,3), (2,1), (2,3), (3,1), (3,2) }
- x1 ? x2
- CtNeq(x1,x2)
I’ll use whatever notation seems right at the time