According to Wikipedia (emphasis in original; footnote omitted): “A knight’s tour is a sequence of moves of a knight on a chessboard such that the knight visits every square only once. If the knight ends on a square that is one knight’s move from the beginning square (so that it could tour the board again immediately, following the same path), the tour is closed, otherwise it is open.
“The knight’s tour problem is the mathematical problem of finding a knight’s tour. Creating a program to find a knight’s tour is a common problem given to computer science students. Variations of the knight’s tour problem involve chessboards of different sizes than the usual 8 × 8, as well as irregular (non-rectangular) boards.”
Knight’s Tour on an 8×8 board:
Not a Knight’s Tour, but still a solution:
More info here (via DimityBrant.com). Hat tip: Cliff Pickover.
prior probability 
What a small world!!! Dmitry Brant is an old friend of my blog, and vice versa! I have stumbled on your blog thanks to a comment you made on a Newcomb’s Paradox video, and here we are, not even six-degrees to Kevin Bacon. I’m going to have to go visit Dmitry’s when I’m done here.
Thanks for paying us a visit … I recall the video: Newcomb’s paradox is a personal favorite.
P.S.: give my regards to Dmitry; his blog is wonderful