http://www.it.uu.se/research/group/astra/ModRef10/papers/Christopher%20Jefferson,%20Wendy%20Moncur%20and%20Karen%20E.%20Petrie.%20Combination,%20Automated%20Gen

http://www.it.uu.se/research/group/astra/ModRef10/papers/Christopher%20Jefferson,%20Wendy%20Moncur%20and%20Karen%20E.%20Petrie.%20Combination,%20Automated%20Generation%20of%20Puzzles%20with%20Constraints%20-%20ModRef%202010.pdf http://www.it.uu.se/research/group/astra/ModRef10/papers/Chr... Is a preliminary paper, we have a longer one in the works.