I've been involved in many interesting projects over the past year and a half since my last update (ouch!). I've managed to wrangle some free time so I'm taking the opportuntity to make a few updates, nothing earth-shattering but perhaps of interest to some.
The update today is on a puzzle I've seen in various guises over the past twenty years. This puzzle is one of a class of many like it. It currently goes under the name "The Nine 9's puzzle". If you would like to see what the puzzle is and what I know about it, you know where to click: The Nine Nine's Puzzle.
The other puzzle that has been occupying much of my free time is the "Attacking Queens Puzzle". This puzzle is at least 10 years old but has recently spawned a contest after a current revival. The puzzle has proved to be computationally challenging. I will be putting details of what I know and what I've done on this puzzle in about a months time after the contest is over. To see what the contest is all about check out The Attacking Queens Contest.
There are links off that page to a site that contains some initial work on the problem and to a discussion group where you can learn a lot, lot more about the puzzle and the trials and tribulations of the contestants. Here is a link to the Final Standings.
Notice I'm slowly sliding down the contest ladder. I've actually hit the proverbial brick wall and can't seem to get a breakthrough.