Responsive doubles

When partner makes a takeout double and RHO raises opener’s suit or bids a new suit, advancer’s double is responsive. It shows 4+ cards in both unbid suits and leaves the choice to the doubler. After partner’s simple overcall, Wbridge5 has no responsive double.

The official help lists only the negative and support doubles as doubles that are not for penalty. Probing Wbridge5 5.12 shows responsive doubles as well. Opener and RHO in these probes played Wbridge5’s own system, at no vulnerability. Ranges are in points, except where marked HCP. Unless noted, advancer held 4–14 HCP.

After a raise

Over (1♣) X (2♣), the double shows both majors. A hand with one 4-card major bids it. The probe gave advancer 3+ cards in each major.

Of the 69 hands with 4+ cards in both majors, 59 doubled. Four passed with 4–6 HCP. The 4♣ row comes from 3 boards.

• ♠AQ97 ♥A763 ♦1093 ♣94: Double (1♣) X (2♣).
• ♠10876 ♥AJ3 ♦Q1094 ♣Q5: Bid 2♠ over (1♣) X (2♣).

Over (1♥) X (2♥), the double shows both minors. A 4-card spade suit takes precedence. The probe gave advancer 3+ cards in each minor.

Of the 76 hands with 4+ cards in both minors, 56 doubled. Six passed with 4–6 HCP, and the 5-5 hands bid 4NT. A broader probe, with any shape and 0–12 HCP, gave the same double on 23 boards, all with 4+ cards in both minors and 0–3 spades.

• ♠J104 ♥QJ ♦KQ65 ♣J982: Double (1♥) X (2♥).
• ♠K ♥K95 ♦AQJ95 ♣10865: Double (1♥) X (2♥).

Neither responsive double moves with vulnerability. Every hand that doubled (1♣) X (2♣) at none vulnerable doubled again at unfavorable and at both vulnerable, and so did every (1♥) X (2♥) doubler at unfavorable. The few changes go both ways when we are vulnerable. Over (1♣) X (2♣), 3 hands with 13–14 HCP bid 3NT instead of 2NT, and 3 hands with 6 HCP passed instead of bidding 2♥ or 2♠ (4 hands with 4–6 HCP with both vulnerable). Over (1♥) X (2♥), one 2NT became 3NT.

After a new suit

Over (1♣) X (1♠), the double shows the red suits. With 5+ hearts and a weak hand, advancer bids 2♥ instead. The probe gave advancer 0–3 spades.

Of the 16 hands with exactly 4 hearts, 4+ diamonds and 4–10 HCP, 13 doubled.

• ♠874 ♥A953 ♦A964 ♣93: Double (1♣) X (1♠).

Over (1♥) X (1♠), the double shows both minors in the same way. A broad probe with 0–12 HCP gave it on 27 boards, all with 4+ cards in both minors, 4–12 HCP and 8–14 points. The 7 hands of that shape that passed held 1–6 HCP.

Other doubles by advancer

The same broad probes, with 0–12 HCP, show two more doubles.

• (1♥) X (1NT): The double shows 10–12 HCP and any shape (49 boards). It is a value double, not a responsive one.
• (1♥) X (2NT): The double shows 7–12 HCP (16 boards) with no common shape.

After an overcall

Over (1♣) 1♥ (2♣), advancer raises with 3 hearts, bids a 5-card suit, or passes. The double appeared only on 2 boards, each with 14 HCP, 4 spades and 2 hearts.

Of the 34 hands with 4 spades and 4+ diamonds, 14 raised hearts with 3 cards, 11 passed, and 2 doubled. The probe gave advancer 0–3 hearts.

The doubler’s rebid

The doubler picks one of advancer’s two suits. It passed the responsive double once in about 1300 boards, with ♠AQJ3 ♥652 ♦AK3 ♣AQ3. Except where marked, the doubler held 12–20 HCP, 0–2 cards in opener’s suit and 3–4 in each unbid major (218–291 boards per auction). Ranges here are in HCP.

Both majors

The doubler raises hearts more freely than spades. With 4♥, 3♠ and a singleton club, 3♥ was bid on 10 of 13 boards with 12–13 HCP, e.g. ♠AK8 ♥K1073 ♦KQ932 ♣9. With a doubleton club, 2♥ was bid on 19 of 26, e.g. ♠A107 ♥KJ75 ♦KJ87 ♣73. With 4♠ and 3♥, 2♠ was bid on all 38 boards with 12–14 HCP, e.g. ♠AQ102 ♥852 ♦KJ83 ♣A6, and 3♠ from 15 HCP. With 4-4 in the majors the choice is mixed: 3♥ on 24 boards, 2♠ on 15, 3♠ on 12.

At unfavorable vulnerability, 6 of the same 218 rebids differed, 4 of them a level higher. For example, ♠K972 ♥K1087 ♦AKQ ♣Q6 bids 4♥ instead of 3♥. On 2 boards the doubler passed the responsive double, with ♠Q65 ♥A74 ♦K10852 ♣K6 and ♠J92 ♥A83 ♦J9765 ♣AK. Neither hand doubled (1♣) at none vulnerable, so there is no pair to compare.

Red suits

As over the raise, a singleton club pushes a minimum to 3♥. The doubler with 3 hearts never bid 2♦. Of 49 such hands with 12–15 HCP, 46 jumped to 3♦ and 3 bid 2NT, e.g. ♠J1082 ♥A32 ♦AKJ82 ♣5.

Both minors

The doubler shows its longer minor. Over a raise it has to bid at the 3 level; over a new suit, a jump shows a 5-card minor rather than extra strength.

With 4-4 in the minors, 3♣ was bid on 39 boards and 3♦ on 32. The 2♠, 3♠ and 4♠ rows come from a second probe of 17–22 HCP hands of any shape with 0–3 hearts (277 boards). There the cuebid was the commonest rebid (136 boards), with no heart stopper or with a long suit, e.g. ♠AKJ ♥975 ♦Q63 ♣AKJ9. A heart stopper bid 3NT, e.g. ♠AK ♥AK3 ♦K76 ♣Q10432. The doubler bid 2♠ with 5 spades and 17–18 HCP (28 of 31 boards), and cuebid with 19+.

With 3 cards in the other minor, a 4-card minor bid at the 2 level (95 of 99 boards). A 5-card minor jumped (61 of 62). For example, ♠K1083 ♥53 ♦A932 ♣AK10 bids 2♦ and ♠AK2 ♥Q3 ♦Q7532 ♣KJ6 bids 3♦. With 4-4 in the minors the choice is mixed: 2♣ on 29 boards, 3♦ on 21, 2♦ on 16.

Not probed

• Vulnerability for the doubles after a new suit and the other doubles by advancer, for the doubler’s rebids other than over (1♣) X (2♣) X (P), and favorable vulnerability. The doubler’s pass of the responsive double at unfavorable came from 2 boards.
• Advancer with 15+ HCP, and (1♦) X (2♦) or (1♠) X (2♠).
• Responsive doubles at the 3-level, e.g. (1♥) X (3♥).
• The doubler’s rebid with 5 cards in an unbid major, except over (1♥) X (2♥) X, and advancer’s call after it.
• Advancer’s double when RHO bids a new suit over partner’s overcall, and over (1M) overcall (2M).