FYI, Jean-Paul Delahaye asks my 2 Sudoku problems below in the January 2006 issue of Pour La Science, the French edition of Scientific American. Two difficult problems... but unique solution exist for each of them. Who will be the first to solve them, or one of them? Christian. -----Message d'origine----- De : math-fun-bounces+cboyer=club-internet.fr@mailman.xmission.com [mailto:math-fun-bounces+cboyer=club-internet.fr@mailman.xmission.com] De la part de Christian Boyer Envoyé : dimanche 4 décembre 2005 23:22 À : 'math-fun' Objet : RE: [math-fun] Problem Puzzler 1999 Nobody seems to have solved my 2 Sudoku problems asked one week ago. But I received direct emails asking me more information, mainly if the problems have unique/no/multiple solutions. No trap in my problems, the 2 answers of my initial questions below are YES. And more precisely: -Problem #1 below has a unique solution (only one new Sudoku puzzle allowing one solution) -Problem #2 below has a unique solution (only one new Sudoku puzzle allowing more than one solution) Who will find and confirm the 2 only signs, one for #1 and one for #2, that can be changed? With the solutions of these 2 new Sudokus. Christian. -----Message d'origine----- De : math-fun-bounces+cboyer=club-internet.fr@mailman.xmission.com [mailto:math-fun-bounces+cboyer=club-internet.fr@mailman.xmission.com] De la part de Christian Boyer Envoyé : vendredi 25 novembre 2005 12:55 À : 'math-fun' Objet : RE: [math-fun] Problem Puzzler 1999 Two new puzzles: 1) Changing ONE AND ONLY ONE sign in the original puzzle (Fig 7 at http://www.maa.org/editorial/mathgames/mathgames_09_05_05.html, is it possible to get another puzzle having again only one solution? 2) Changing ONE AND ONLY ONE sign in the original puzzle, is it possible to get another puzzle with more than one solution? I have the 2 answers, hoping that they are correct. Christian. -----Message d'origine----- De : math-fun-bounces+cboyer=club-internet.fr@mailman.xmission.com [mailto:math-fun-bounces+cboyer=club-internet.fr@mailman.xmission.com] De la part de ed pegg Envoyé : jeudi 24 novembre 2005 21:20 À : math-fun Objet : Re: [math-fun] Problem Puzzler 1999 Christian, Yes, a spreadsheet with all solutions is near the bottom of my column. --Ed Pegg Jr --- Christian Boyer <cboyer@club-internet.fr> wrote:
Jean-Paul Delahaye publishes in the new issue of Pour La Science a very interesting article on Sudokus. He asked a very strange Sudoku problem WITHOUT any given numbers, only ">" and "<" signs between cells. He mentions that this problem was published in Puzzler, 1999, and that he does not know the solution.
I have the solution, sent this morning to J.-P. Delahaye.
Now looking for "Puzzler 1999" on Google, I find that Ed Pegg Jr. wrote an article in September 2005 including the same astonishing puzzle, figure 7 "Greater Than Sudoku" in:
http://www.maa.org/editorial/mathgames/mathgames_09_05_05.html
Perhaps that somebody else had already the solution? Ed, did you receive a solution to your article?
Christian.