Bridge

Contract Bridge · the four-hand classic

Bidding

Board 1

Dealing…

0We (North-South)

0They (East-West)

Opponent

Level

Scoring

Explain the bidding Show all four hands at the end

Auction

Deals

Rules

The cards. All 52 are dealt out, 13 to each of the four players. North-South play as one partnership against East-West, and partners sit opposite each other. In each suit the ace is highest, then king, queen, jack, ten, down to the two.
The auction. Starting with the dealer and going clockwise, each player makes a call: pass, a bid, or a double. A bid names a number of tricks over six and a trump suit — ♣, ♦, ♥, ♠ or no trumps — so 1♠ offers to win 7 tricks with spades as trumps and 7NT offers to win all 13 with no trump suit. Each bid must be higher than the last: a higher number, or the same number in a higher-ranking denomination (♣ lowest, then ♦, ♥, ♠, no trumps).
Doubles. You may double the opponents' bid to raise the stakes; they may redouble. Any new bid wipes the double away.
The contract. The auction ends when a call is followed by three passes. The last bid becomes the contract; if all four players pass at the start, the deal is thrown in and a new one is dealt. The player of the winning side who first named that denomination becomes declarer.
The play. The player to declarer's left leads to the first trick. Declarer's partner then lays their hand face up as dummy and takes no further part: declarer plays both hands. You must follow suit if you can; if not, you may play any card, including a trump. The highest trump wins the trick, or if no trump was played, the highest card of the suit led. The winner of each trick leads to the next.
Making the contract. Declarer's side needs 6 + the number bid tricks. Extra tricks are overtricks; falling short means going down, and the defenders score the penalty.
Vulnerability raises both the rewards and the penalties. In duplicate it follows the board number; in a rubber, a side is vulnerable once it has won a game.

Scoring

Tricks bid and made: ♣ and ♦ 20 each, ♥ and ♠ 30 each, no trumps 40 for the first and 30 after that. Doubled counts double, redoubled four times.
Game is 100 trick points or more (3NT, 4♥/4♠, 5♣/5♦, or a doubled part-score). Bidding and making game scores a bonus of 300, or 500 when vulnerable; a part-score scores 50.
Slams: a small slam (12 tricks bid and made) scores 500, or 750 vulnerable; a grand slam (all 13) 1000, or 1500 vulnerable.
Overtricks: at the trick value undoubled; 100 each doubled (200 vulnerable), doubled again if redoubled. Making a doubled contract adds 50 for the insult, or 100 redoubled.
Undertricks go to the defenders: 50 each (100 vulnerable) undoubled. Doubled and not vulnerable: 100, then 200, 200, and 300 for each after that. Doubled and vulnerable: 200, then 300 each. Redoubled doubles those numbers.
Rubber bridge keeps trick points below the line — two games win the rubber, worth 700 if the other side has no game, 500 if they have one. Everything else goes above the line. (Honours are not scored here.)

Contract	Not vul.	Vulnerable
3NT made	400	600
4♥ made	420	620
6♠ made	980	1430
Two down, doubled	−300	−500

Tips for beginners

Count your points. Ace 4, king 3, queen 2, jack 1. Add one for each card over four in a long suit. About 12 points is enough to open the bidding; 25 or so between the two hands is enough for game.
Find a fit. Eight cards between you in a major suit is worth far more than a thin 3NT — raise partner's major whenever you hold three or more.
Lead the top of a sequence (K Q J, Q J 10) — it never costs a trick. From a long suit without one, lead the fourth highest.
Third hand high, second hand low. When partner leads and you play third, put up your highest card; when the lead comes from your left, play low and keep your honours over dummy's.
As declarer, count your tricks before you play card one. With a trump suit, draw the opponents' trumps first — unless you need to ruff losers in the short hand.

How the computer bids

Openings. 12+ points, five-card majors and a better minor. 1NT is 15-17 balanced, 2NT 20-21, and 2♣ is artificial and strong with 22+. Weak twos in ♦/♥/♠ show a six-card suit and 5-10 points; a seven-card suit pre-empts at the three level.
Responses. Raises are limited: 2 of partner's major is 6-9, 3 is 10-12, 4 is the real thing. 1NT is 6-10, 2NT 11-12 and 3NT 13-15. Over 1NT, 2♣ is Stayman and asks for a four-card major.
Competing. Overcalls at the one level show 8-17 with a good five-card suit; a takeout double shows 12+, shortness in their suit and support for the others.
Where it stops. Before every call it adds its own points to the range partner has shown, and only bids what the two hands are worth: 25 for 3NT or four of a major, 28 for five of a minor, 33 for a small slam.
Turn on Explain the bidding and every call in the auction table can be tapped to see why it was made.

How the computer plays

It never sees your cards. Each of the three computer players is told only what that seat may know: its own hand, dummy once it is face up, the auction and the cards already played.
Rules of thumb guide the early tricks: top of a sequence, fourth best from length, third hand high, second hand low, cover an honour with an honour, ruff when it gains, draw trumps when it has control and finesse towards dummy's honours.
Then it calculates. Once few enough cards are left it deals the unseen cards out hundreds of ways — consistent with every suit each player has shown out of — and plays each one out exactly, with perfect play on both sides, keeping the card that wins the most tricks on average.
Levels. Easy follows the rules of thumb and sometimes slips. Medium starts calculating with six cards left, Hard with eight and looks at far more layouts.
Claims are checked the same exact way: the rest of the hand is played out against the best defence there is.