ON CERTAIN CROSS SUM PUZZLES
Seppo Mustonen · 2006
A class of cross sum puzzles called Survo puzzles will be studied. Survo puzzles are somewhat related to Kakuro cross sum puzzles but played on a simple, open rectangular grid and without limiting to integers from 1 to 9. In a Survo puzzle the task is to fill an m × n –table by integers 1, 2,...,mn so that each of these numbers appears only once and their row and column sums are equal to integers given on the bottom and the right side of the table. Often some of the integers are given readily in the table in order to guarantee uniqueness of the solution and/or for making the task easier. During last months I have presented various examples of Survo puzzles (”Survoristikoita” in Finnish) for active Survo users in the newsgroup (www.survo.fi ⇒ Keskustelu). In harder cases various computational features of the Survo system have been helpful.