Makeable Contracts and Double Dummy Analysis

Double Dummy Analysis (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 their 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).

DDA Panel
Figure 1: Double Dummy dialog panel

To have BridgeComposer calculate and display the DDA, use the "Board→Double Dummy" command or the "Tools→Double Dummy All Boards" command.

Figure 1 shows the dialog panel for the "Board→Double Dummy" command.

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.

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.

Below each hand diagram, BridgeComposer displays the DDA in one of five formats (figures 2a through 2e). Select the DDA format for a BridgeComposer document using "Format→Board Layout", General tab.

DDA in Makeable Contracts format
Figure 2a: Makeable Contracts format
DDA in Grid (2 rows) format
Figure 2b: Grid (2 rows) format
DDA in Grid (4 rows) format
Figure 2c: Grid (4 rows) format
DDA in Grid (4 rows, no par) format
Figure 2d: Grid (4 rows, no par) format
DDA in Grid (4 rows, in diagram) format
Figure 2e: Grid (4 rows, in diagram) format

Notice that the Grid (2 rows) format gives the DDA in terms of number of tricks (0 to 13). However, the three grid formats with four rows give it in terms of the bid level of makeable contracts, and show a hyphen when less than seven tricks can be made.

Following the DDA, the par score and par contracts are shown in Makeable Contracts and Grid (4 rows) formats. The par score is shown in Grid (2 rows) format.

When Position Matters

DDA grid with varying trick counts
Figure 3

Sometimes one partner will make a different number of double dummy tricks than the other in a given strain. In grid (2 rows) format, this is displayed as shown in figure 3, 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.

Verifying the DDA

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.

Software Credit

The program used by BridgeComposer to compute the DDA and the optimal plays is DDS, courtesy of Bo Haglund.

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