Again, no more than 20 attributes may be counted towards a logic or combinatorial puzzle.

A list of resources that are good sources for logic/combinatorial puzzles include:

• http://zpuzzle.omijal.org/?section=puzzle_archive
• http://en.wikipedia.org/wiki/Category:Logic_puzzles
• http://www.chiark.greenend.org.uk/~sgtatham/puzzles/
• http://en.wikibooks.org/wiki/Puzzles
• http://www.ics.uci.edu/~eppstein/cgt/
• http://www.cut-the-knot.org/Curriculum/index.shtml
• http://www.spellscroll.com/viewquestions/?tag=combinatorics

There are likely many other puzzles out there… if you find something of interest, research it and present me with a case for allowing you to undertake it.