1. Matrix Modelling: Déjà Vu Pierre Flener (Uppsala) Alan M. Frisch (York) Brahim Hnich, Zeynep Kiziltan (Uppsala) Ian Miguel, and Toby Walsh (York)

2. What is new about Matrix Modelling? People have been using matrix models for years: –Progressive Party Problem [Smith et al. 95]. –Template Design [Proll & Smith 98].

3. Warehouse Location. Again. Isn’t this just the standard model? I’ve seen something very similar to this in an old Solver manual…

4. Diversity? So what isn’t a matrix model?

5. We Already Are People have already been matrix modelling (implicitly) for years.

6. Constraint Types Sums of rows/columns of arrays are already easy to express. As are channelling constraints between matrices And even specialised constraints such as the scalar product.

7. Ease of statement Only a fool would do this any other way. Like writing a specialised daemon for this colour constraint…

8. Improved Propagation Wouldn’t you rather be outside right now?

9. Symmetry-breaking Set variables are more natural than lexicographic ordering: –This type of symmetry is created when we assign indices to identical objects. –E.g. Golfers

10. Lexicogaphic ordering does not break all symmetry: 01 10 10 01 01 10 Symmetry-breaking(2)

11. Variable Indexing This (again) is not new: –It is already a feature of most constraint programming languages.

12. Wouldn’t You have Rather Seen the Steel Mill Talk?