Wednesday, May 03, 2006

May 2006: Tait's 8 Coin Puzzle

In 1884 P. G. Tait presented the following puzzle (which he encountered while riding on a train). Start with eight adjacent coins alternating heads and tails. By moving four pairs of neighboring coins (and without changing their order), rearrange the coins to obtain four tails followed by four heads with no gaps between any of the coins.

For example, here is a solution for six coins using four moves.

Your solution should list the orders of the coins (including the gaps) at each stage.

May winners: Evan Templeton, Jon Rogers, Jared Lease, Gordon Clark, Shashwat Acharya

P.G. Tait, "Listing's Topologie," Philosophical Magazine, January 1884

[See the solution to last month's puzzle, Queen Domination]

April 2006: Queen domination (solution)

There are many solutions to this puzzle, but they are all variations of the following solution: a3, e4, b8, d11.