src/HOL/ex/Sudoku.thy
2008-12-03 webertj 2008-12-03 more examples
2007-06-03 wenzelm 2007-06-03 tuned document;
2007-01-10 webertj 2007-01-10 no unfolding necessary anymore (refute does that automatically now)
2005-12-14 webertj 2005-12-14 ex/Sudoku.thy