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Thursday, May 8, 2008

Blackwood Protection Against Troublemakers
by Jim Kaplan

Column vetter Paul Laliberte reports:

“Although the situation arises only once in a blue moon, a bridge partnership needs some mechanism that will permit an exchange of information over Blackwood interference.”

Here’s the kind of situation he has in mind:

West North East South
Pass 1S Pass 3S
Pass 4NT 5H ?

“Without this bidding tool, it is impossible to know whether to sign off at the five level or carry on to slam. One such convention is DOPI (Double Zero, Pass One), which uses a double to show no aces, a pass to show one ace, the bid of the cheapest suit over the interference to show two aces, the bid of the second cheapest suit to show three aces, and so on. It is also possible to use Roman Key Card responses to DOPI:

“Double — 0 or 3 of the 5 key cards (four aces, trump king)
“Pass — 1 or 4 key cards
“Next suit — 2 or 5 key cards without trump queen
“Second cheapest suit — 2 or 5 key cards with trump queen

“Another Blackwood interference convention is DEPO, in which a double shows no aces, two aces or four aces while a pass shows one or three. Since zero is considered an even number, the initials DEPO stands for Double Even, Pass Odd. It is possible to uses Roman Key Card responses to DEPO as well:

“Double — 0, 2 or 4 key cards
“Pass — 1, 3 or 5 key cards

“Last week my mom Lois and I found ourselves playing in an ACBL IMP-mini game on OK Bridge, an Internet competition. We were sitting North-South on Board Nine, with North dealing and East-West vulnerable”:

NORTH (Paul)
S 7
H K J 10
D Q J 10 8 6 4
C J 9 2
S K J 10 8 4 S A Q 9 2
H 3 H Q 5 4
D 7 D K 5 3
C Q 10 8 6 4 3 C A K 5
SOUTH (Lois)
S 6 5 3
H A 9 8 7 6 2
D A 9 2
C 7

The bidding proceeded as follows:

North East South West
Pass 1C 2H* 2S
3H 4S Pass 4NT
5H 6S All Pass

* Pre-emptive weak two-bid
Opening lead: heart jack

West didn’t have the 10+ high-card points his 2S suggested; it would have been better to make a negative double and then bid spades. That way, East-West never would have investigated a possible slam. And West didn’t have enough to bid 4NT either. Aceless holdings are seldom worthy of a slam inquiry.

“In any case, feeling that playing 5H (presumably doubled) would not be too costly at favorable vulnerability, I opted to take action after West’s Blackwood inquiry. I realized, too, that my 5H call might muddy the water should East-West decide to carry on in spades. Evidently, at this juncture, East had a problem. A long hesitation made it clear that the partnership hadn’t discussed how to deal with my interference. Certain that partner had to hold at least one ace, East confidently committed to a small slam in spades.

“I led the heart jack, hoping to find partner with the ace and subsequently pin the queen if it was held by one of the opponents. As things turned out, trapping the queen was not the real issue. Partner won the heart ace and laid down the diamond ace for the setting trick. If I had not interfered, the opponents would undoubtedly have stopped in 5S, making.

“At times, making trouble can pay dividends.”

P.S.: If East had been using DOPI, a 5S bid would have shown two aces. Using DEPO, East would have to double and hope partner will assume two aces instead of four. That’s the likely total, since East might have done more than bid 4S with all four.

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