Below each hand diagram, BridgeComposer displays the double dummy analysis (DDA), in either makeable contracts format (figure 1) or grid format (figure 2).
(Following the DDA are the par score and par contracts.)
In figure 1, the makeable contracts are listed as: NS 4♦; EW 4♣; EW 1♥, that is, North-South four diamonds, East-West four clubs, and East-West one heart.
DDA: For any particular deal, given the declarer and the trump suit (or notrump), the double dummy result is the number of tricks the declarer will win when all four players can see all 52 cards, and each player always plays to his or her best advantage. A complete DDA consists of 20 results, calculated by considering, in turn, each of the four players as declarer playing in each of the five strains (four possible trump suits plus notrump).
The DDA is shown in grid format at the bottom of figure 2, and in figure 3 as displayed by the BridgeComposer Board→Double Dummy command.
The makeable contract of "NS 4♦" comes from the DDA results showing that North and South will take ten tricks when declaring with diamonds as trump. The other makeable contracts are figured similarly.
Of course, in actual play you can’t see all 52 cards, so sometimes the DDA results are unrealistic. But the DDA nonetheless indicates what is possible on a given layout of the cards, both for declarer and for the defense.
Sometimes one partner will make a different number of double dummy tricks than the other in a given strain. In grid format, this is displayed as shown in figure 4, where in hearts North will take 9 tricks but South will take only 8.
In makeable contracts format, this situation would be shown as "N 3♥; S 2♥".
This example also shows that the double dummy tricks differ for East and West in spades, diamonds and clubs.
You may see how a DDA result was arrived at by using the BridgeComposer View→Next To Play command.
Click here to see an example.
In case you were wondering, the four numbers below the West hand (3, 4, 19, 14 in figure 4 above) are the high card points held by each hand (not directly related to makeable contracts or DDA). See Hand Evaluation.
The program used by BridgeComposer to compute the DDA and the optimal plays is dds.dll, courtesy of Bo Haglund.
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