Category : A Collection of Games for DOS and Windows
Archive   : CRIBBAGE.ZIP
Filename : CRIBBAGE.DOC

CRIBBAGE Version 1.0 Documentation








Why Cribbage?....................2
Command Line Arguments...........3
Keyboard Controls................4
Rules of the Game................6
Some Strategy...................10
Cribbage Trivia.................15
Programming Notes...............16








Program and documentation copyright, 1989, by Craig R. Hessel
All rights reserved









This program was written for IBM-compatible microcomputers running under
PC-DOS or MS-DOS version 2.0 or higher. IBM and PC-DOS are registered
trademarks of International Business Machines, Inc., and MS-DOS is a
registered trademark of Microsoft Corporation. Cribbage was around
before there were lawyers.


Program and documentation may be freely copied and distributed provided

- both are distributed together, each in unmodified form, and
- no fee is charged.

Exception: Non-profit organizations (and non-profit organizations only)
may charge a nominal fee to cover cost of materials and handling.



CRIBBAGE 1.0 Documentation - 2




Why Cribbage?


I first learned about cribbage when I was a kid. Computers then (I doubt
I'd even heard of them at the time) were bulky machines that figured
ballistic missile trajectories for people in white coats. When computers
got into the hands of real people a decade or so ago, computer games
quickly became a part of the landscape. The first games were, like
cribbage, just conversions of older games to the new medium. Then came
Star Trek--the game. Remember? An explosion of new games uniquely
suited to computers followed--arcade games, role playing games, and so
on. Cribbage for the computer is actually a throwback.

So why bother? If you've never played the game before, it's hard to
explain. The game itself is tricky to learn. It was invented several
centuries ago by an English nobleman who probably kept tweaking the rules
until he was the only person of his day who could figure them out. The
rules have such an odd mix of ways to score points, that a beginner is
apt to accuse his opponent of making them up as he goes along. But
cribbage grows on you. It's the kind of game that prompts grizzled
veterans to maintain meticulous records over the years of wins and losses
and skunks, dollars won and dollars lost. The longer you play the game,
the more intriguing it becomes. To this day, I'm still learning the
game. I've written this program because I enjoy both programming and
cribbage. That doesn't mean I'm very good at either, but that doesn't
matter a bit. I hope to pass on here a little enthusiasm for what I've
found to be enjoyable and worthwhile pastime.

For the veteran player, the program provides automatic record-keeping.
Not only that, it lets you play duplicate cribbage. After all, the
reason for record-keeping or playing for money (admit it now) is to see
who's better at the game. [Jeb: "That puts me up 'bout $12.80 since '66,
Zeke." Zeke: "That's only 'cause we upped the stakes back in '78." Jeb:
"But you oughtn't ta count yer lucky streak in '76 when we found that
thar five missin' from the deck."] Duplicate cribbage against a common
foe (the computer) can help answer that question, or at least give you
something new to argue about. [Zeke: "Pairin' that seven was dumb, Jeb.
You oughta played the eight." Jeb: "Dang it, Zeke. I won." Zeke: "You
gotta play dumb to beat a dumb machine. It cheats anyhow."]

If you are a beginner, you can ignore these extra features and just try
your luck against the machine. The game rules are covered later,
followed by another section that gives some basic strategy. You might
want to skip ahead to those sections first, since the next few sections
assume you already know how to play the game.



CRIBBAGE 1.0 Documentation - 3




Command Line Arguments


Syntax: CRIBBAGE [flags [seed]] Example: CRIBBAGE IASD 123

As indicated, the flags are optional. Flags must be bunched (no spaces
between them). Their order and case are irrelevant. At most 8 flags may
be specified on the command line.

Flag Meaning Default
---- ------- -------
M Forces a monochrome display. Use this Display color if color
flag or the next if you have a color video adapter found,
adapter, but only a monochrome monitor. else display black and
Common with laptops, for example. white (monochrome).

I Forces an inverse monochrome display. Same as above.
Takes precedence over above flag.

B Forces slower BIOS screen writes. Use Direct screen writes.
if you get unacceptable screen flicker.

L Log match games and statistics to file No log active. Data is
CRIBBAGE.LOG in current directory. The displayed whether or
data is appended to the file. not log is active.

Q Disables sound during match, except for Full sound.
error beeps (illegal card choice, open
drive door during log, etc.)

R Ruthless game, with penalties. On Friendly game -- your
overpeg, your score is corrected and scoring mistakes are
computer takes the excess. On underpeg, corrected.
you just lose the points.

D Forces you and computer to alternate Loser of game deals
first deals from game to game. Use first hand of next game.
flag for duplicate match play to insure Standard cribbage rule.
identical conditions for each game on
each replay by computer or other person.

S Tells computer to use seed found on Seed taken from system
command line. Seed is 1 - 8 hex digits time. Seed determines
(0 - 9 or A - F). card sequence.

A Automode. Computer plays itself. Use You play computer.
to replay a match (with same seed) to
see how computer fairs with same cards.

Note: Replays of matches with the same starting seed work, even though
some replayed games differ in length, because the computer internally
deals out dead hands to a total of 16 after each game. I've never
noticed a game longer than 12 hands. The average game is about 9 hands.



CRIBBAGE 1.0 Documentation - 4




Keyboard Controls


The basic keyboard controls during the match are the four cursor keys and
the Return key. Use the right and left cursor keys to move a flashing
pointer below your cards. Point to the desired card, then select it by
pressing Return. Use the up and down cursor keys to move your flashing
back peg when it's time to score points. The up arrow moves the peg
forward (right or left, depending on which street you are on) to increase
your score. The down arrow moves the peg in the direction that decreases
the score. Press Return to insert the peg.

Although you may hold the cursor key down to get automatic key repetition
(a BIOS feature on all IBM compatibles), that's a lousy way to accurately
move your peg the right number of holes. You have to look closely
afterwards to see where the peg is sitting, then adjust it to the right
hole. Instead, just tap the up arrow once for each point you wish to
score, then press Return. This was hardly worth mentioning, since
you'll probably be doing it anyway before you finish playing your first
hand, even if you haven't read this. By the way, note that the cribbage
board itself is a 120-hole tournament board, rather than the usual 60-
hole board. [Jeb: "Fifteen two 'n a double run fer ten. That's game,
Zeke." Zeke: "Huh? We ain't been 'round but once yet."]

During the match, you will also be prompted frequently just to press
Return before going on. This lets you absorb whatever activity has taken
place before continuing. In test versions of the program, I tried timing
out many situations automatically, but I got annoyed occasionally when I
missed something. Some of the obnoxious patter by your opponent is
still timed out after a second or so.

The Esc key is the unconditional program abort key (the 'boss is coming'
key). You get no chance to change your mind. There may be a slight lag
if the program is currently thinking about a discard or a pegging play.

There are two instances in which you are prompted for a Y/N response.
After each game, you are prompted with "Continue match?". Answer as you
see fit. If you are logging the match and want to quit here, make sure
to answer N, rather than pressing Esc. That insures you get the match
statistics appended to the log file. The games will already be logged,
since each summary is appended at game end. The other Y/N prompt is "Log
file error. Try again?". This results from a problem appending to the
log file, e.g., an open drive door or a read-only CRIBBAGE.LOG. Fix the
problem if you can, then answer accordingly. Your obnoxious opponent
also occasionally asks rhetorical questions. These expect and deserve
no response.

The last control key is the F1 key. When pressed at any game prompt, it
invokes automode momentarily. That is, if you are discarding, the
computer will discard for you. If you are making a pegging play, the
computer will play for you. If you are scoring, the computer will score
correctly for you. The F1 key also works at any "Press Return" prompt.
In fact, by repeatedly pressing the F1 key, you can play a game exactly
as it would be played if the A flag were included on the command line.



CRIBBAGE 1.0 Documentation - 5




This effectively provides you a short cut in figuring out how your
opponent plays. You can, of course, just play a few matches and see how
he plays from the opposite side of the table. But playing a game with
the F1 key is like looking over his shoulder as he plays, before you sit
down to play him yourself.

Note that the F1 key is not a true 'help' key, since it does not just
give advice. It goes ahead and makes a play. This is intentional. It
is one thing to observe your opposition from the sidelines, but when you
decide to do battle, you are on your own.

The key controls described so far apply to normal play. If you have
included the A flag on the command line to invoke automode, there is less
to do. You may still abort anytime with Esc, but otherwise each game
zips by quickly (less than a half minute per game on my 286 laptop). At
the end of each game, the prompt "Optional Return here pauses Automode"
appears below the game summary. You have three seconds to press Return,
or else the next game begins (up to 100 games maximum). If you press
Return in time, the prompt "Continue match?" appears. This waits
indefinitely for an answer.

Aside from generating duplicate match results for comparison with your
own match results, automode can also be used to generate typical cribbage
statistics. By logging the data, you can run 100-game matches unattended
and check out the results later.



CRIBBAGE 1.0 Documentation - 6




Rules of the Game


This section sticks to the rules, more or less, so it will be dry
reading. Bear with me. I dislike documentation that mixes rules and
strategy together. The two should be separate. I once tried to figure
out how to play the Japanese game of Go from what was obviously a
butchered translation of something. It was impossible to distinguish
rules from suggested strategy. It was frustrating, to say the least.

Match conditions:

Matches consist either of a preset number of games or else are played to
a preset number of 'match points'. The winner of the match is then the
player with the most match points. The program does not ask which method
you are using, but instead lets you terminate the match after any game
(up to 100 games maximum). You can just play games indefinitely, if you
wish. But its not quite cricket to play and win a few games, and then to
decide you're in the middle of a match. The computer, though, has no way
of knowing this.

Match points are awarded only for winning a game. You get no points for
losing. There are no ties in cribbage. The number of match points for a
win varies, depending on how soundly you defeat your opponent. This is
standard cribbage. The point systems in use, however, vary. This
program awards 2 points for a plain win, 3 points for a 'skunk', and 4
points for a 'double skunk'. Some systems count the double skunk as just
a skunk. Others give more weight to skunks and double skunks. In any
case, win/skunk/double skunk have the standard meanings defined below.

Game conditions:

Games are played until either player accumulates 121 game points. These
will just be called points from here on. The player reaching 121 points
is the winner of the game. Points are always scored by one player at a
time in cribbage, so it is not possible for both players to reach 121.
This asymmetry is a critical feature of the game. In many games, the
loser will be holding enough unclaimed points to win, had it been his
turn to score instead of his opponent's.

If the losing player has 60 or fewer points, the game is a double skunk.
This occurs only rarely. If he has 61 to 90 points, the game is a skunk.
Otherwise, the game counts as an ordinary win for the player with 121.

The point ranges for win/skunk/double skunk are not arbitrary. Points
are usually tallied on a cribbage board, with the players using opposite
sides of the board to keep score. Each player's side is further divided
into 'streets' of 30 holes each. Points are tracked by leap-frogging two
pegs down the streets. The street boundaries coincide with the point
cutoffs for win/skunk/double skunk. There might be such a thing as a
triple skunk if the loser of a game were to end up still in the first of
the four streets, but I've never heard of it happening, and no match
scoring system takes it into consideration.

There is, by the way, no requirement to use a cribbage board to keep


CRIBBAGE 1.0 Documentation - 7




score. But the scoring in cribbage takes place frequently, making the
use of pencil and paper impractical. The visual effect of the peg
positions on the board is also important to experienced players when they
make decisions during the game.

Cut for deal:

Players cut for first deal in a match, with the low card by rank winning
the deal. Aces are always low in cribbage. By standard cribbage rules,
the first deal in each subsequent game is awarded to the loser of the
previous game. This program provides an option (the D flag) that causes
the privilege of first deal from game to game to alternate between
players. The purpose of this is to enable duplicate match play.

The deal:

During games, the deal alternates between the players -- called 'dealer'
and 'pone' -- on successive hands. The roles interchange each hand. It
is important to know whether you are dealer or pone in any situation in
cribbage, as many rules are applied differently, depending on the roles.

To start a hand, the dealer shuffles the deck, offers to let the pone
cut (he may decline), then deals six cards each, face down, alternately,
to the pone and himself. These are tournament rules. In friendly games,
opponents who know and trust each often dispense with the offer of a cut.
Cribbage has long been known as a 'gentleman's' game, but nowadays some
tournaments offer prizes in excess of $1000, and unfortunately the degree
of trust seems to be inversely proportional to the stakes involved.

Some folks also adhere to a quaint custom that perversely penalizes
players for the instinctive offering or acceptance of a cut prior to most
card games. If the dealer offers a cut, and the unaware opponent
accepts, the dealer scores a point. If the opponent, however, is paying
attention and declines, he scores a point. This is not a standard
cribbage rule and is not included in the program. The program handles
shuffling and dealing automatically.

Discarding:

Each player next places two of his six cards face down into a common hand
called the crib. Later, the crib will be scored by the dealer. The
choice of discards is important and is discussed in the strategy section.

The cut:

Next, the pone removes a portion of the undealt remainder of the deck,
without looking at any of the cards he has removed. (It is a peculiar,
but unfortunately common, practice for the pone to expose the bottom
card of those he has removed for both players to see.) The dealer then
turns face up the top card from the stack remaining. This card is called
the 'cut'. Later, the cut will be a fifth card common to the dealer
hand, the pone hand, and the crib when those hands are scored.

The dealer is entitled to score 2 points now if the cut is a jack.



CRIBBAGE 1.0 Documentation - 8




Pegging:

After the cut, a process called pegging takes place. Only the four
retained dealer cards and four retained pone cards are used. The players
turn their own cards face up, one at a time, separately, and in the order
prescribed next. The cards are not mixed, so that the hands may be
scored later, but the program displays the eight cards in a row for
convenience as they are turned up. During the pegging, a running sum of
the ranks of the cards played is maintained. This sum is called the
'count'. The count begins at zero and may occasionally be reset to zero
during pegging. When computing the sum, aces have a count-value of 1 and
face cards have a count-value of 10. The count may never exceed 31.

The pone plays first by turning up one of his cards and calling the
count. The play continues, alternating between the two players, until
either the count reaches 31 or until one of the players cannot make a
play that would keep the count at 31 or below. If the count reached 31
exactly, the count is reset to zero, and the play resumes with the
opponent of the player who last played a card. The program indicates
that the count has been reset by flipping the exposed cards face down
again. If the count was less that 31, the player who cannot make a play
announces 'go' to so indicate. His opponent then continues playing cards
until the count reaches 31 or until he too no longer has a play that
would keep the count at 31 or below. If he did not reach 31, he too then
announces 'go'. In either case, the count is reset to zero and play
continues, as above, starting with the opponent of the player who last
played a card. This process is repeated until all eight cards from both
hands have been played. The program announces 'go' for you automatically
during the pegging.

This completes the bare mechanics of pegging. More important, though,
are the ways in which points are scored during the process. These are
described next. In the following, a pegging sequence refers to ONLY
those cards played since the count was last at zero.

1. In any pegging sequence ending with a count less than 31, the
player who last played a card is entitled to 1 point, called a 'go'
point.

2. Playing a card which brings the count to exactly 15 or 31 entitles
the player to 2 points.

3. Within a pegging sequence, playing a card that matches the rank of
the last 1/2/3 played card(s) entitles the player to 2/6/12 points.
That is, score 2 points for a pair, 6 points for 3-of-a-kind, and
score 12 points for 4-of-a-kind.

4. Within a pegging sequence, playing a card which completes a run of
three or more cards entitles the player to 1 point for each card in
the run. A run is a series of cards of consecutive rank (aces are
always low in cribbage), in any order.

These scoring plays can be combined on a single play. For example, the
card sequence 4-6-5... at the start of pegging entitles the pone to five
points when he plays the 5, since the count is at 15 and since the 5


CRIBBAGE 1.0 Documentation - 9




completes a run of three cards. In cribbage jargon, this would be
announced as "Fifteen two and a run of three for five". By the way, the
dealer's play of the 6 as the second card probably indicates he is
desperate for points and will play a card next that scores a run. Then
again, he may just be holding the other three 6's.

Note that it is impossible to score 12 points for 4-of-a-kind in the
pegging for any rank higher than a seven, since that would always push
the count past 31. Remember -- runs, pairs, 3-of-a-kind, and 4-of-a-kind
cannot extend beyond one pegging sequence.

Also note that cribbage players frequently combine 'go' points with other
pegging points when possible. However, the program requires 'go' points
to be scored separately. Sorry about the inconvenience--couldn't avoid
it easily.

Hand scoring:

Once the pegging is completed, the three hands--pone hand, dealer hand,
and crib--are scored in precisely that order. The cut is a fifth card
common to all three hands. Crib points are scored by the dealer. The
rules for scoring are identical for all three hands, with the exception
of the way flushes are scored for the crib. The exception is noted
below. As in the pegging, there are several ways to score points. The
total score for a hand will usually be a combination of several ways.

1. 4-of-a-kind scores 12 points, 3-of-a-kind scores 6 points, and each
pair scores 2 points, as in the pegging. A way to remember these
values is to note that 3-of-a-kind can be thought of as three
distinct pairs (3 * 2 = 6) and 4-of-a-kind can be thought of as six
distinct pairs (6 * 2 = 12). The hand 3-3-3-6-6 contains a pair
and 3-of-a-kind for 2 + 6 = 8 points due to rank multiplicity.

2. Each distinct run of three or more cards scores 1 point for each
card in the run. Note that as long as two runs differ by at least
one card, they are considered as distinct. For example, the hand
4-5-5-6-6 contains four runs of three cards each for a total of 3 +
3 + 3 + 3 = 12 points due to the run contributions. Again,
remember that aces are low in cribbage. Q-K-A is not a run.

3. If one of the four retained cards in the hand is a jack whose suit
matches the suit of the cut card, then score 1 point for 'nobs'.

4. If the four retained cards in the pone or dealer hand are all the
same suit, score 4 points for a flush. If, in addition, the suit
of the cut card also matches, score a fifth point. In order to
score a flush in the crib, however, all five cards must be the same
suit. In this case, score 5 points for the crib flush.

5. Each distinct combination of two or more cards whose count-value
sums to 15 scores 2 points. As in the pegging, the count value of
a card is the same as its rank, with face cards having a count-
value of 10 and aces having a count-value of 1. This can get
tricky. For example, the hand 3-3-3-6-6 contains five different
card combinations that sum to 15, and thus has a 10 point scoring


CRIBBAGE 1.0 Documentation - 10




contribution from 15-count combinations. A very common 15-count
combination is a five and a face card (or ten).

As a short exercise, try scoring these two dealer hands: 5(cut)-5-5-5-J
and A(cut)-A-6-7-8. Assume the jack scores nobs in the first hand and
that the four retained cards in the second hand are the same suit. The
correct scores are in the Cribbage Trivia section.

Once the crib is scored, the hand is completed and the pone becomes
dealer for the next hand, and so on, until the game is concluded.

Penalties:

In friendly games, opponents will often correct each others scoring
mistakes. That is, one player will call attention to the mistake and let
the player in error make his own correction. Never touch your opponent's
pegs in cribbage. That is one of the taboos of the game, somewhat akin
to lowering your poker hand below the edge of the table in a poker game.
I'll be darned if I know what the penalty is for this, because I've never
seen it done. I may find out, though, since this program makes friendly
corrections for you.

In ruthless games, penalties are enforced for taking too many or too few
points in any scoring situation. As with match scoring rules, there are
a few variations in common practice. This program enforces these rules
in a ruthless game: 1) if you score too many points, your score
corrected and the computer takes the excess points you tried to take,
and 2) if you score too few points, you have in effect already penalized
yourself, so nothing else is done. Some folks are more ruthless than
this, and in the second case will take the points you missed. A further
tournament rule in practice (not enforced by the computer) is that if you
take too many points, and in doing so claim victory, you forfeit the
game immediately.

Miscellaneous:

There are some considerations in real life games that do not come up in
games versus a computer. For instance, suppose you are pone, and a jack
is cut. You wait a moment for the dealer to take his 2 points. He seems
to be asleep at the wheel (you'll come to hate that expression very
quickly--play a few games versus the computer to see what I mean). When
you play your first card, the dealer loses the opportunity to score the
points. How long do you wait? The program solves this problem in
ruthless games by displaying a scoring prompt after every cut. You tap
Return to score zero, or else you take 2 points. In friendly games, the
scoring prompt is only displayed when a jack is actually cut. In real
life games, though, these are not the alternatives. What you actually do
is wait a 'reasonable' amount of time, then you make your play. Every
cribbage player instinctively knows what 'reasonable' means here, but you
can't put it in terms of numbers. You wait long enough to give your
opponent a fair chance to score, but not so long as to wake him up. For
those of you who hate computers, by the way, take heart. It's just this
kind of common sense situation that frustrates computers.



CRIBBAGE 1.0 Documentation - 11




Some Strategy


This section will try to give beginners some rules of thumb to follow.
Basically, we'll look at discarding and pegging, with a hint or two about
positional play at the end of the section. Remember, rules of thumb are
not meant to cover every situation.

Discarding strategy:

Beginners usually find discarding more difficult than pegging because
there are more choices. There are 15 ways to discard two cards from a
six card hand, while you never have more that 4 choices when pegging.
When you are discarding, you are juggling several considerations. You
want your final hand score to be as high as possible. If you are dealer
you want the crib to score well; if you are pone, not so well. You also
want to keep good pegging cards. And finally, you want to weigh all this
against positional play, which dictates whether you should be cautious
at the moment, or aggressive. Sound complicated? I guess it does. So
how do you handle complicated things? You break them up into manageable
pieces. This is a programmer's approach to problems.

For starters, let's look at discarding from the perspective of making
your final hand score the best possible. It turns out that this is
usually the most important consideration in discarding. The other
factors you have less control over. It also helps to know that most
points in a game are from hand scoring. Dealer and pone hands average
about eight points each. The average crib is four and a half to five
points. The pone usually averages about two points pegging and the
dealer averages a point or so more than that. So, roughly speaking, pone
and dealer hand scoring accounts for 16 out of every 26 points in a game.
After looking at things this way, we can adjust for other considerations.

The unknown in the final hand score is the cut card. Let's ignore that
too for the moment. So what are we left with? We just want to find the
four cards that by themselves add up to the most points. This is a good
beginner's rule of thumb for discarding. Although the hand-scoring rules
covered in the previous section pertain to five card hands, note that all
except the 'nobs' rule permit you to evaluate a score for just four
cards. It still may seem like a lot of work to evaluate all the possible
four-card combinations in a hand, but after playing awhile, you'll soon
notice that most of the combinations aren't even worth looking at. At
this point, just try to narrow down your choice to two or three
possibilities that score the highest.

Next, let's consider the effect the discard has on the crib. As dealer,
naturally you want to throw good cards, since you get to score the crib
later. What are good cards? For sure, a pair or two cards that form a
15-count are good cards, since they are a sure two points. Other good
cards are two cards consecutive in rank, like 6-7 or 3-4. These
increase the chance of runs in the crib. Also, a five with any other
card, a 2-3 combination, and an A-4 combination are all good discards.
Fives are easily the most important cards in the game of cribbage. The
abundance of 10-count cards (face cards and tens) in the deck means that
fives will be part of 15-count card combinations (which are worth two


CRIBBAGE 1.0 Documentation - 12




points) more frequently than any other rank. The same consideration
makes 5-combinations important also.

As pone, you take the opposite view. You want to avoid throwing the card
combinations that help the crib. If you can, you would like to throw
combinations like 10-K, 9-K, or 9-Q. As a rule of thumb, never (almost)
throw a five in your opponent's crib.

Now look back at the two or three four-card combinations that score
highest and check the corresponding two-card discards for their effect on
the crib. If you still have two choices that seem pretty even, a good
rule of thumb for breaking the tie is to save the hand with lower ranking
cards. These tend to improve the pegging potential of the hand.

Another good rule of thumb when discarding is never to break up a 'double
run'. A double run is a combination like 2-3-4-4 or 9-10-10-J, i.e., a
combination of two runs and a pair. This guarantees you at least eight
points and has potential to score much higher with a favorable cut.

Let's look at a few examples, starting with an easy hand. Suppose as
dealer you hold 2-3-4-5-9-10. There are three ways to save 5 points: 2-
3-4-9, 2-3-4-10, and 3-4-5-10. The corresponding discards are 5-10, 5-9,
and 2-9. Since its your crib, the 5-10 discard is best, since it's two
sure points and fives are great crib helpers. If you are pone with the
same hand, then the 2-9 discard is best.

Now suppose as dealer you hold 2-3-4-4-7-7. Keeping either 2-3-4-4 or 4-
4-7-7 saves 8 points. The corresponding discards are 7-7 and 2-3. These
are both good discards. Save the double run. Its a good rule of thumb.
But what if you are pone? You hate these kind of hands. The safest
discard is 4-7. In situations where extreme caution is dictated, many
players will choose this, even though it means breaking up a double run.
If it's early in the game, and you feel lucky, throw the 7's.

Finally, a trick hand. As dealer or pone, you hold 2-2-3-3-6-6. It
seems clear cut, since 3-3-6-6 is worth 8 points. You might be surprised
to find that experienced players will usually discard the two 6's. The
rule of thumb fails us here, since 2-2-3-3 has tremendous scoring
potential. Sometimes two birds in the bush are better than one in the
hand. If cribbage were too easy, it wouldn't be nearly as interesting.

A last word of encouragement on discarding. If you are a beginner, it
can be frustrating to play an opponent who never needs more than a couple
seconds to discard. First, he has probably been playing for years. He
should be a little faster at it. Second, realize that this can work to
his DISadvantage sometimes. There may be some type of hands he discards
one way just because he's always done it that way, even though it's not
the best way. You are new to the game and still think before acting.
Make it work to your advantage. If you wonder about a hand, look at it
later. You can even sit down and play through every possible cut to see
which discard averages out best. (Try that, for example, with 2-2-3-3-6-
6.) Maybe it will just be one small thing that you learn. But you'll
come back with a little more confidence each time you play. [Junior:
"I'll bet ol' Zeke don't know that throwin' a five always gets ya at
least two points...".]


CRIBBAGE 1.0 Documentation - 13





Pegging strategy:

Although there are fewer choices in pegging, it is probably harder to
master the art of pegging than of discarding. Rules of thumb in the
pegging are less clear cut than in discarding. This is basically because
pegging strategy should depend largely on how your opponent plays. This
is true to some extent in discarding. If your opponent is very
conservative, and never throws good cards in your crib, don't waste your
own good cards by throwing them there also. (Pegging, by the way, is the
weakest part of the computer's play. It is a little too predictable and
does not follow the above advice--it does not try to adjust its style
according to your playing tendencies.) Keep this 'disclaimer' in mind
when reading on here.

A 4 is generally considered the best lead by pone. This prevents the
dealer from reaching a count of 15 on the next play and forces him to
make a play that gives the pone the opportunity to reach 15. As pone,
however, you should occasionally decline to lead a 4, to keep your
opponent off guard.

Leading from a 5-combination as pone is also common (e.g., leading a 3 if
you also have a 2). Almost a third of the deck is comprised of 10-count
cards, so dealer likely has one or more. If he plays one, pone can score
two points. The dealer knows this, however, and will often decline to
play a 10-count card next.

A 5 is a poor lead. You might be tempted to lead a 5, for example, from
5-J-Q-K at the end of a game if you are 11 points from going out. You
are trying to lure your opponent into playing a card you can pair up.
The unusual lead instead will trigger all kinds of warning signals in
your opponent (even if you 'cleverly' pretend the 5 slipped out
accidentally). Instead, play one of the face cards, and hope that your
opponent will routinely (and incorrectly in this instance) play a 5 to
score two points. Then you may pair the 5 for your eventual winning
points.

If you are dealer, you should generally assume that pone has a 5 and try
to trap it. The pone almost never throws a 5 in the crib, so he is more
likely to have a 5 than any other card by rank. He will hold a 5 after
discarding about four hands out of every ten. As pegging proceeds, the
play of 10-count cards, 4's, or 6's by pone should reinforce this
initial assumption, while other plays weaken the assumption.

As the pegging winds down, and you have seen a few opponent cards, you
should assume the opponent's remaining card or cards fit best with what
he has shown. E.g., if your opponent has shown 6-8-9 already, guard
against a 7 first, then against a 6 or a 9 next. If you play a 2, and he
surprises you by pairing the 2, don't consider that as losing points.
When the hands are scored, his total will be poor and that will more than
offset those two pegging points.

A good piece of pegging advice for beginners is NOT to make scoring plays
automatically. While you may end up making the play anyway, you should
always do a damage assessment first and consider how the opponent will


CRIBBAGE 1.0 Documentation - 14




follow up the play. Give your opponent credit. Particularly early on in
the pegging, when he has more freedom in card selection, he will be
trying to guard against your possible scoring plays.

The toughest decision in pegging is whether or not to pair an opponent's
card. You stand to gain two points, but risk giving up six points. Four
points is a big swing in the pegging. Tournament players are overly
cautious in this respect, probably thinking that skill will carry the day
anyway. Beginners, on the other hand, frequently pair up without a
second thought. I read a book on the game about 15 years ago (sorry--
can't remember the author or title for sure--by Anderson or Andersen?) in
which the author tried to study the question statistically. His
conclusion was that, other things being equal, you will in the long run
give up as many points as you gain by pairing in the pegging. By 'other
things being equal' he meant by not taking into consideration either your
opponent's style of play or basic positional strategy. If your opponent
tends to play from his pair early in the pegging, then you should tend to
decline the early pairing opportunity. Positional strategy, discussed
next, affects both discarding and pegging.

Positional strategy:

Cribbage players use a term called 'playing position' that refers to
playing aggressively or cautiously depending on the game score, i.e., on
the peg positions on the board. I'll use an analogy here. If you have
ever taken a driver safety course or have seen public driving safety
announcements, you should know that when driving you do not keep your
eyes on the bumper of the car in front of you. You should look well
ahead for potential accident situations. Truck drivers all know this.
Those rigs cannot be stopped on a dime.

In cribbage, just watching to see whether you are a couple points behind
or ahead of your opponent is like staring at the bumper in front of you.
You may think you're in a close game and you may even gain a couple
points as you turn the corner onto home street, but then kapow! An
accident. There you are at 103 points and he's at 99. But he's dealing
next and you are pone. Think about it. Who's probably going to win?

The dealer on a typical hand scores 16 combined points. The pone
typically scores 10 combined points. So he is likely to be around 115 as
pone next hand, while you sit glumly dealing at 113. His truck is
probably going to coast home as your Maserati spins its wheels in the
ditch. Then you think back a couple hands to the furious pegging where
you both scored a couple of times on run combinations and you had a net
gain of a couple points. What if you had blocked the runs by playing
your king? Take away 10 points from your score and 8 points from his and
the score would be 103 to 107. Then you could have had a real battle
down home street.

This is what positional play is all about. Think ahead. Try to maneuver
so you will be dealing when you have 95-100 points. Sometimes it will
take risky pushes in the pegging. Sometimes it will mean breaking up
your hand to throw real clunkers into your opponent's crib.



CRIBBAGE 1.0 Documentation - 15





Cribbage Trivia


1. The highest scoring hand in cribbage is four 5's and a jack, when
the jack counts for nobs. This scores 29.

2. Perhaps the most frequently mis-scored hand in cribbage is A-A-6-7-
8. This scores 13 (or 17 with a flush). Usually, the A-A-6-7 15-
combination is overlooked.

3. The only cribbage hand that cannot be improved by the cut is four
aces.

4. The dealer in cribbage is guaranteed a point in the pegging (unless
pone goes out first).

5. Any cribbage hand containing a 5 (or cards that add up to 5) is
guaranteed to score at least 2 points.

6. No matter what you discard, there is some possible three-card
combination that can bring the crib score to at least 12 points.

7. The lowest hand point total impossible to achieve is 19 points.
Zero point hands are facetiously called '19-pointers'.

8. The largest hand improvement a cut can produce is 20 points, i.e.,
when a 5 is cut to 4-4-6-6.

9. The largest improvement a cut can produce for a hand which is worth
nothing initially is 14 points, e.g., when a 5 is cut to the crib
holding of 3-4-6-7 and all five cards are the same suit.

10. Any pairing cut to the hand 6-7-8-9 brings the hand score to 16
points (20 if the holding is a flush).

The following results are from computer simulations, but seem reasonable:

11. The most common pone hand is Q-J-10-5, with K-Q-J-5, J-10-9-5, 8-7-
6-5, and 9-8-7-6 as the next four runners-up. The dealer top five
in order are Q-J-10-5, 9-8-7-6, K-Q-J-5, 8-7-6-A, and K-6-5-4.
Together, these account for about 4% of all pone/dealer hands.

12. Dealer and pone hands each average about eight points, while the
crib averages about four and three-quarter points.

13. Dealer averages one to one and a half points better than pone
during pegging. A combined average of five pegging points per hand
is typical, but may be lower in cautious tournament play.

14. The player dealing first in a game wins 55% to 60% of the time, if
the players are evenly matched.



CRIBBAGE 1.0 Documentation - 16




Programming Notes



This program was written in assembly language. Most of the effort went
into the discarding decision and pegging decision routines.

The discard decision routine is fairly straight-forward. The program
cuts the 46 outstanding cards to each possible 4-card holding to assess
its average score and maximum possible score. A precomputed table (one
for pone and one for dealer) with 91 entries holds the average expected
crib score for the 91 possible discards by rank. The expected crib score
for the discard is fetched from the table. A separate routine computes a
risk value based on the peg positions. The expected crib score is
weighed by the risk value, and then added to (dealer) or subtracted from
(pone) the average score for the 4-card holding. The maximum score is
risk-weighed and added in also. A small adjustment is made for pegging
potential. The discard with the best result is chosen. Near game end,
if any choice guarantees enough points to go out, only those choices are
assessed, with the assessment based only on safe pegging considerations.

The pegging decision routine is recursive, with consideration of own
play, opponent next play, then own next play at a minimum. If opponent
play scores, look-ahead is extended to own play following non-scoring
opponent play. Choice is determined by summing own play scores and
subtracting risk-weighed opponent scores, with opponent plays further
weighed by estimated likelihood that opponent holds card of that rank.
The probability of each rank for opponent is estimated from 1820 entry
table (one for pone and one for dealer), with adjustments for inferences
made during pegging. Table holds precomputed frequencies for the 1820
possible 4-card opponent holdings by rank.

The tables mentioned above were constructed independently of the random
card routines. A simplified discard decision routine (assuming normal
risk and ignoring flushes, pegging potential, and endplay) was used to
discard from all possible 6-card hands by rank. This determined the 1820
entry frequency tables (for held cards) and new 91 entry average crib
score tables (for discards). The process was repeated iteratively until
the average crib score tables and the hand frequency tables stabilized.

The discard routine is very good. The pegging routine needs work, since
it still produces some bonehead plays (like leading a five in some
situations), is too predictable, and pushes too often. But overall, I
think the program provides a worthy foe. This was my goal from outset.

A tip here on printing the log file. To print the suit symbols with an
Epson-compatible printer, first make sure you have the printer set to
print the IBM extended character set (find the right dip switch), then
send an escape 6 (an ASCII 27 followed by an ASCII 54) to the printer.
This tells the printer to print symbols for the low ASCII characters.
Then do COPY CRIBBAGE.LOG PRN.

CRH - 15 Oct 89