FreeCell
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FreeCell is a solitaire card game similar to Klondike.
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Rules
- Shuffle, then deal the 52 cards face up in 8 columns with each card visible but only the end card of each column fully exposed. Four columns will have 7 cards, the other only 6.
- Apart from the columns, there are four single card free cells and four suit piles (foundations). The objective is to get all the cards into the foundations.
- Single exposed cards may be moved:
- Column to column, placing the card on a card of the next rank and different colour suit. (E.G. Place a red 3 on a black 4.) (Aces are low.)
- Column to FreeCell, any exposed card as long as there is an empty cell.
- FreeCell to Column, as column to column.
- Column to suit home pile. Next card in order, starting with the Ace, ending with the King. Each suit is completely independent.
- FreeCell to suit home pile. As column to suit home pile.
The terms in italics are defined in solitaire terminology.
History
One of the oldest ancestors of FreeCell is Eight Off. In the June 1968 edition of Scientific American Martin Gardner described in his "Mathematical Games" column, a game by C. L. Baker that is similar to FreeCell, except that cards on the tableau are built by suit instead of by alternate colors. This variant is now called Baker's Game.
Paul Alfille changed Baker's Game by making cards build according to alternate colors, thus creating FreeCell. He implemented the first computerized version of it for the PLATO educational computer system in 1978. The game became popular mainly due to Jim Horne, who learned the game from the PLATO system and implemented the game as a full graphical version for Windows. This was eventually bundled along with several releases of Windows.
Today, there are many other FreeCell implementations for every modern system, some of them as part of Solitaire suites. However, it is estimated that as of 2003, the Microsoft version remains the most popular, despite the fact that it is very limited.
Strategies
A sequence of several cards with alternating colors can be moved at once by moving cards to vacant cells and/or temporarily placing them in empty columns. If the move involves temporarily placing a card in an empty column it is called a supermove in FreeCell terminology.
Cards can be safely moved to the foundations without a chance of being further used, if the value of the foundations of the different color are greater than the card face value minus 2, and the value of the other foundation of the same color is greater than the card face value minus 3.
Culture
FreeCell, highly popular in the United States, has developed its own subculture. Much information about the game can be found at FreeCell FAQ (http://www.solitairelaboratory.com/fcfaq.html) which is maintained by Michael Keller.
While there are actually 52!, or approximately 8.06x1067, possible games, the original Microsoft package includes 32,000, generated by a 15-bit random number seed. These games are known as the "Microsoft 32,000". Later versions of Microsoft FreeCell include more games, of which the original 32,000 are a subset.
Jim Horne added this intriguing sentence to the Help file which remains through modern Microsoft versions: "It is believed (although not proven) that every game is winnable." This was known at the time to be untrue in its strictest sense. Games numbered -1 and -2 were included as a kind of easter egg to demonstrate that there were some possible card combinations that clearly could not be won. Nevertheless it started a flurry of interest in the question of whether all of the Microsoft 32,000 could be beat. Smart players could win most games most of the time, but that wasn’t proof either way.
The Internet FreeCell Project by Dave Ring, which was finished in October 1995, took on the problem. Ring assigned 100 consecutive games chunks across volunteering human solvers and collected the games that they reported to be unsolvable, and assigned them to other people. This elegant project used the power of multiprocessing, where the processors were human brains, to quickly converge on the answer. Only one game defied every human player's attempt, the famous game number 11,982.
Subsequently various computer programs have confirmed this result, but it's nice to know people harnessing the power of the Internet and human cooperation found the answer first. These are the same forces, by the way, that power Wikipedia.
In later implementations of Freecell in Microsoft Windows, there are 1,000,000 games. Of these 1,000,000 games, 8 have been found to be unsolvable. They are games No. 11,982, No. 146,692, No. 186,216, No. 455,889, No. 495,505, No. 512,118, No. 517,776, and No. 781,948.
One way to "win" at any Microsoft Freecell game was added as a way to help the original software testers; push Ctrl-Shift-F10 at any time during the game. Click Abort to win, Retry to lose, or Ignore to cancel. Double-click any card for the results. Unfortunately this doesn't actually solve the game, it just throws the cards into electronic piles without regard for the rules.
Automatic Solvers
One of the passions of several FreeCell enthusiasts was to construct computer programs that could automatically solve FreeCell. Don Woods wrote a solver for FreeCell and several similar games as early as 1997. This solver was later enhanced by Wilson Callan and Adrian Ettlinger and was incorporated into their Freecell Pro software.
Another known solver is Patsolve of Tom Holroyd (http://members.tripod.com/professor_tom/). Patsolve uses atomic moves, and since version 3.0 incorporated a weighting function based on the results of a genetic algorithm that made it much faster.
Shlomi Fish (http://www.shlomifish.org/) started his own solver (http://fc-solve.berlios.de/) starting of March 2000. This solver was simply dubbed Freecell Solver. This solver is unique because it can use meta-moves, groups of moves that aim to achieve a certain end. The most comprehensive list of solvers that is known (http://fc-solve.berlios.de/links.html#other_solvers), contains links to other solvers. A note which is in order is that new solvers are constantly written as part of assignments or projects of some university courses.