Cribbage
Image source: By — Geoffrey Franklin, CCA 2.0
Summary
Cribbage is for two players. We describe one round of Cribbage in this summary. Shuffle the deck, and deal each player six cards. Each player chooses two cards from their hand to add to a face-down crib. A start card is turned up from the deck, and the dealer scores two points if it is a Jack. In a round, players play one card at a time, alternating when possible as long as the sum of ranks on cards played does not exceed 31. Various points are scored based on patterns in the sequence of cards played. The total is reset to zero, rounds are repeated until all cards are played. Finally, played cards are returned to their owners, and more points are scored for sets, runs, and sums in their hand plus the face-up start card. The dealer also scores for the four cards in the crip plus the face-up start card. the player with the most points wins.
Rules of Play
These rules are summarized from https://www.pagat.com/adders/crib6.html.
Variants Used
We include two rounds of Cribbage, since the ownership of the crib alternates each round. This allows for fair comparisons of player algorithms.
Related Games
Cribbage is an adding game. Other games in this genre include Ninety-Eight and Costly Colours.
Information Flow
The diagram above visualizes information flow in Cribbage using a single random rollout in CardStock. Visibility is attached to card locations, so all cards in a location share the same visibility; information is revealed or concealed as cards move between locations and ownership changes.
Public locations are shown in green, hidden locations in yellow, private locations in blue, and memory locations in light gray. Locations containing cards with distinct backs are indicated with bold borders. Rectangles denote ownership (players or table), and directed edges show card movement between locations and resulting visibility changes. Taken information is shown with red dotted edges (public to private/hidden), and shared information with blue dashed edges (private cards transferred to another player).
RECYCLE Code
The rules for Cribbage are coded in RECYCLE, a card game description language, to encourage standardized implementations across different systems.
You can also Download the code.
;; Cribbage for 2
;; https://www.pagat.com/adders/crib6.html
(game
(setup
;; Set up the players, 2 players each on their own team
(create players 2)
;; Create the deck source - French
(create deck (game iloc STOCK)
(deck (RANK (A, TWO, THREE, FOUR, FIVE, SIX,
SEVEN, EIGHT, NINE, TEN, J, Q, K))
(COLOR (RED (SUIT (HEARTS, DIAMONDS)))
(BLACK (SUIT (CLUBS, SPADES)))))))
;; each player is the dealer once
(stage player
(end (all player 'P (== ('P str DEALER) TRUE)))
(do (
(shuffle (game iloc STOCK))
(set (game points PIPS)
(((RANK : K) 10) ((RANK : Q) 10) ((RANK : J) 10)
((RANK : TEN) 10) ((RANK : NINE) 9) ((RANK : EIGHT) 8)
((RANK : SEVEN) 7) ((RANK : SIX) 6) ((RANK : FIVE) 5)
((RANK : FOUR) 4) ((RANK : THREE) 3) ((RANK : TWO) 2)
((RANK : A) 1)))
(set (game points SEQUENCE)
(((RANK : K) 13) ((RANK : Q) 12) ((RANK : J) 11)
((RANK : TEN) 10) ((RANK : NINE) 9) ((RANK : EIGHT) 8)
((RANK : SEVEN) 7) ((RANK : SIX) 6) ((RANK : FIVE) 5)
((RANK : FOUR) 4) ((RANK : THREE) 3) ((RANK : TWO) 2)
((RANK : A) 1)))
;; Deal 6 cards to each player
(all player 'P
(repeat 6 (move (top (game iloc STOCK))
(top ('P iloc HAND)))))
(set ((current player) str DEALER) TRUE)
(set ((current player) str STATE) PLAY)
(set ((next player) str STATE) PLAY)))
;; each player picks two for the crib
(stage player
(end (all player 'P (== (size ('P iloc HAND)) 4)))
(choice (
(any ((current player) iloc HAND) 'C
(move 'C (top (game iloc CRIB))))))
(choice (
(any ((current player) iloc HAND) 'C
(move 'C (top (game iloc CRIB)))))))
;; Set up the start card
(do (
(move (top (game iloc STOCK))
(top (game vloc START)))
;; Two for his heels
((== (cardatt RANK (top (game vloc START))) J)
(inc ((current player) sto SCORE) 2))))
;; play the cards
(stage player
(end (all player 'P (== (size ('P iloc HAND)) 0)))
(choice (
;; if you can add to the pile without going over
((> (size (filter ((current player) iloc HAND) 'FC
(<= (+ (game sto TOTAL)
(score 'FC using (game points PIPS))) 31))) 0)
(any (filter ((current player) iloc HAND) 'FC
(<= (+ (game sto TOTAL)
(score 'FC using (game points PIPS))) 31)) 'C
(do (
(move 'C (top ((current player) vloc PILE)))
(remember 'C (top (game mem SEQUENCE)))
((== ((next player) str STATE) GO)
(cycle next (current player)))))))
;; if you cannot add without going over 31, then you say GO to the other player
((== (size (filter ((current player) iloc HAND) 'FC
(<= (+ (game sto TOTAL)
(score 'FC using (game points PIPS))) 31))) 0)
(set ((current player) str STATE) GO))))
(do (
((!= ((current player) str STATE) GO)
(do (
;; reset the total, so calculations take less time
(set (game sto TOTAL) (sum (game mem SEQUENCE) using (game points PIPS)))
;; fifteen for two
((== (game sto TOTAL) 15)
(inc ((current player) sto SCORE)))
;; thirty-one for two, end the round
((== (game sto TOTAL) 31)
(do (
(inc ((current player) sto SCORE) 2)
(all player 'P (set ('P str STATE) GO)))))
;; Looking for pairs in sequence
((and (>= (size (game mem SEQUENCE)) 2)
(all (top 2 (game mem SEQUENCE)) 'C
(== (cardatt RANK 'C)
(cardatt RANK (top (game mem SEQUENCE))))))
(do (
(inc ((current player) sto SCORE) 2)
((and (>= (size (game mem SEQUENCE)) 3)
(all (top 3 (game mem SEQUENCE)) 'C
(== (cardatt RANK 'C)
(cardatt RANK (top (game mem SEQUENCE))))))
(do (
(inc ((current player) sto SCORE) 4)
((and (>= (size (game mem SEQUENCE)) 4)
(all (top 4 (game mem SEQUENCE)) 'C
(== (cardatt RANK 'C)
(cardatt RANK (top (game mem SEQUENCE))))))
(inc ((current player) sto SCORE) 6))))))))
;; find longest run in sequence starting at and including the top
(inc ((current player) sto SCORE)
(size (run top 3 (game mem SEQUENCE) using (game points SEQUENCE)))))))
;; neither player can play a card?
((or (all player 'P (== ('P str STATE) GO))
(all player 'P (== (size ('P iloc HAND)) 0)))
(do (
;; Point for last card
((!= (game sto TOTAL) 31)
(inc ((current player) sto SCORE) 1))
;; move cards to PLAYED for later scoring
(all player 'P
(repeat all (move (top ('P vloc PILE))
(top ('P vloc PLAYED)))))
(repeat all (forget (top (game mem SEQUENCE))))
(set ((current player) str STATE) PLAY)
(set ((next player) str STATE) PLAY)
(set (game sto TOTAL) 0)))))))
;; non-dealer scores first
(do (
(cycle current (next player))))
;; now we score the players cards
(stage player
(end (all player 'P (== (size ('P vloc PLAYED)) 0)))
(do (
;; fifteen for two
(all (subsets (union (game vloc START)
((current player) vloc PLAYED))) 'CC
((== (sum 'CC using (game points PIPS)) 15)
(inc ((current player) sto SCORE) 2)))
;; Pair scoring
(all (partition RANK (union (game vloc START)
((current player) vloc PLAYED))) 'CC
(do (
((== (size 'CC) 2) ;; Pair
(inc ((current player) sto SCORE) 2))
((== (size 'CC) 3) ;; Pair Royal
(inc ((current player) sto SCORE) 6))
((== (size 'CC) 4) ;; Double Pair Royal
(inc ((current player) sto SCORE) 12)))))
;; RUN SCORING
;; Three cards of consecutive rank (irrespective of suit), such as ace-2-3, score 3 points for a run.
;; A hand such as 6-7-7-8 contains two runs of 3 (as well as two fifteens and a pair) and so would score
;; 12 altogether. A run of four cards, such as 9-10-J-Q scores 4 points (this is slightly illogical - you
;; might expect it to score 6 because it contains two runs of 3, but it doesn't. The runs of 3 within it
;; don't count - you just get 4), and a run of five cards scores 5.
(all (runs largest 3 ((current player) vloc PLAYED)
using (game points SEQUENCE)) 'PR
(do (
((== (size 'PR) 3)
(inc ((current player) sto SCORE) 3))
((== (size 'PR) 4)
(dec ((current player) sto SCORE) 4))
((== (size 'PR) 5)
(dec ((current player) sto SCORE) 5)))))
;; Flush scoring
(all (partition SUIT ((current player) vloc PLAYED)) 'CC
(do (
((== (size 'CC) 4) ;; all same suit in hand
(do (
(inc ((current player) sto SCORE) 4)
((== (cardatt SUIT (top 'CC))
(cardatt SUIT (top (game vloc START)))) ;; Bonus
(inc ((current player) sto SCORE)))))))))
;; One for His Nob
((any ((current player) vloc PLAYED) 'C
(and (== (cardatt RANK 'C) J)
(== (cardatt SUIT 'C)
(cardatt SUIT (top (game vloc START))))))
(inc ((current player) sto SCORE)))
;; Discard cards
(repeat all
(move (top ((current player) vloc PLAYED))
(top (game vloc DISCARD))))
;; Move crib cards if it is the end of the dealer's turn to count points
((and (all player 'P (== (size ('P vloc PLAYED)) 0))
(> (size (game iloc CRIB)) 0))
(do (
(repeat all (move (top (game iloc CRIB))
(top ((current player) vloc PLAYED))))
(cycle next (current player))))))))
;; make sure turn passes correctly
(do (
(move (top (game vloc START))
(top (game vloc DISCARD)))
(repeat all (move (top (game vloc DISCARD))
(top (game iloc STOCK))))
(cycle current (next player)))))
(scoring max ((current player) sto SCORE)))