H. Zantema, december 2009 – january 2010.
Just like ordinary sudokus in these puzzles numbers from 1 to 9 have to be filled in such a way that every
column, every row and every indicated 3x3 square block contains the numbers 1 to 9, each exactly once.
A group of cells containing a number means that the numbers to be put in this group sum to the given number.
It is not required that all numbers in such a group are distinct.
All puzzles have a unique solution; this has been checked by the program yices: yices proves that a formula
describing the given rules, the given sums, and a difference with the intended solution, is unsatisfiable. Most of
them I solved by hand, and I indicate whether I found them easy, medium, or hard.
7. (very hard, not solved by hand)
10. (very hard, not solved by hand)