Programming the Game of Hearts
A pragmatic critique
by Clement Washburn
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The programmer of the game of hearts appears to have given
perfect memory to opponents of the live player, but along with that he or she
has given them imperfect strategy. This is to be expected if the programmer
seeks to entertain, for who would want to play the game if opponents
consistently won?
What follows is a diagnosis of the program for the game derived
only from playing it, not from an analysis of the code, which is inaccessible.
It is assumed that all dealing results from random shuffles in the Microsoft
version of the game. (There are at least two exceptions to the assumption of
random shuffles, as noted below.)
There are four players. The object of the game is to avoid
taking points. Each heart taken counts one point against the recipient and the
queen of spades counts thirteen. Game is concluded when any player reaches 100
points. If, however, a player takes all 26 points (all 13 hearts and the queen
of spades), then each opponent is given 26 points. The player with the lowest
score wins.
In the first deal, players are required, first, to pass any
three cards to their left; in the second deal, they must pass three cards to
their right; thirdly, three cards are passed across to the player opposite them;
fourth, to pass no cards but keep what cards were dealt. In subsequent deals,
these passing procedures are repeated. The opening lead is always the two of
clubs.
It is a fact that a reasonably astute player, without perfect
memory, can score an average of close to 2 (or even less), that is, coming in
second in a field of 4, where 1 is first and 4 is last. Thus, after 149 games,
the player here studied (here called Player with a capital "P")
averaged a score of 2.15.
The mean, if all players are of equal skill, is of course, 2.5,
the average of the sum of 1, 2, 3, and 4. (The standard deviation of a randomly
distributed universe of scores is 1.118—the square root of the mean of squares
of the deviations of each of four values from the mean of 2.5. The sampling
error is the root of the quotient of the deviation, 1.118, divided by a sample
size of 149 or .087. Hence, a mean score of 2.15 differs from the 2.5 mean by
.35, more than four standard errors from the mean. The result is statistically
significant well beyond the one-tenth percent level. That is, so high a score is
unlikely to be due to chance and more likely to be due to relative skill.)
What are the defects in the strategy of opponents?
Opponents too frequently fail to sweep all 26 points, thereby
failing to award 26 points to each other player. In 86 games in which there were
successful sweeps, Player made 59 successful sweeps to only 27 sweeps made by all
three opponents. (It would be expected, under an equal opportunity
assumption, that each of the four players would successfully execute one-quarter
of the successful sweeps. But Player recorded 68.6 percent of the successful
sweeps. This is "off the chart" in terms of probability, too highly
improbable to warrant an assumption of equal skills.)
Of course, failed attempts to sweep lower the average gain of
anyone who tries too often. But one successful sweep that penalizes each of
three opponents with 26 points is worth much more than a failed attempt in which
somewhat fewer than 26 points are incurred by the one who fails. The remarkably
high frequency with which Player can sweep suggests that perhaps favorable hands
are more often dealt to him, thereby vitiating the assumption of random dealing.
Opponents usually fail to recognize when Player is sweeping,
that is, trying to take all the hearts and the Queen (Q) of spades. They slough
off, say, the King (K) and Q of hearts, thereby making good Player's Jack (J)
and 10 (when, of course, he either holds the Ace or it has already been
sloughed.) They make this same mistake when one of them attempts a sweep. They
lead the Q of spades, which counts 13 points against them, when they have an
alternative card to exit from their hands.
An opponent will make a sweep even when it insures that he or
she will lose the game by driving one player to 100 points while leaving himself
in second or third or fourth place. An analogy from football is the team that
decides to kick the point after touchdown in the few seconds left to play rather
than pass into the end zone even though the single point awarded for
successfully kicking will lose the game while a successful pass will at least
tie it.
Opponents see the advantage of passing honor cards in hearts but
often fail to see the advantage of passing a low heart which may foil an attempt
to sweep; holding a deuce of hearts will likely prevent a player from taking all
the hearts except in the case where he holds an extremely long heart suit and so
can draw all of opponents' hearts.
There are doubts that opponents will, when possible, hold off,
say, sloughing the Q of spades (or a heart) until the most threatening opponent
(the lowest scoring) is likely to take the trick. It is clearly advantageous to
dump points on the leading opponent. Dumping on some opponent who is already
near having 100 points while you are far behind, in third or fourth place,
merely insures that you will not end up at or near the head of the pack.
It appears that only one time in five will the player be dealt
the Q of spades when the hand is played as a "hold" rather than as a
pass left, right, or across. This fact, of course, is an exception to the
inference drawn, above, that each deal is random.
In passing three cards, opponents seem to fail to void
themselves in clubs so that they may slough such dangerous cards as the Ace or
King of spades on the opening lead. In four games, Player did this ten times
and, as well as could be determined, opponents did it once. They also seem to
slough low spades, a tactic that is almost never appropriate. They also pass
some of the lowest hearts, which also seems inappropriate. Equally important,
opponents will sometimes fail to pass the Q of spades when the opportunity
presents itself.
The only real strength in the strategy of opponents seems to be
a result of perfect memory of what cards have been played. Thus, for example, if
a player is attempting a sweep and towards the end of play he holds, say, a
losing club, an opponent will save a winning club and take the lead to capture a
heart, by a slough from another player. Similarly, an opponent will, when
holding a high heart, sometimes capture the second or third lead of a lower
heart during an attempted sweep.
Conclusion—»
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