...The problem is a very hard combinatorial optimisation problem, invented by Craig Knecht. More can be read about it at:
http://en.wikipedia.org/wiki/Water_retention_on_mathematical_surfaces
Craig's website for the problem:
http://www.knechtmagicsquare.paulscomputing.com/
The solver is mainly based on the theory and ideas from my bachelor thesis, which I wrote at Uppsala University, Sweden, for the Astra Group which does research about Constraint Programming and related technologies:
Water Retention on Magic Squares with Constraint-Based Local Search
http://urn.kb.se/resolve?...