Even well-known puzzles retain their power, as was made clear again and again last month at the seventh "Gathering for Gardner." These conferences of mathematicians, puzzlers, game-players and magicians at the Ritz-Carlton here began as personal tributes to Martin Gardner, Scientific American's legendary Mathematical Games columnist, and now take place without the master's presence (he is 91). During four days of talks and tricks, the oldest puzzles mixed freely with the newest.-- Edward Rothstein, TheNew York Times , April 2006