Semiforcing 1NT
The 1NT response to a major opening is semiforcing. The semiforcing 1NT is a dustbin for hands with 5–10 HCP and no other available bid. However, with a flat hand, 3-card support, and exactly 6 or 11 HCP, Wbridge5 bids 1NT instead of direct support. Probing Wbridge5 5.12 shows that other 11 HCP hands bid a 2/1 instead.
In Wbridge5, the 1NT is more forcing than an American semiforcing 1NT.
- Opener always rebids 2♣ with 3 cards if balanced.
- A 4-card lower-ranking side suit is never passed by suit quality.
Flat raises
The 4-3-3 side suits make it awkward to play a suit contract. With a 6 or 11 HCP flat raise, Wbridge5 bids 1NT rather than raising. For example, ♠J72 ♥10654 ♦J83 ♣A75 and ♠Q64 ♥A852 ♦K96 ♣Q64 both bid 1NT over 1♠.
Such 1NT is a bet on opener’s usual rebidding. Opener’s rebid provides good continuations like forcing 1NT. Opener’s pass leads to a mediocre but acceptable result. To make the pass rare, Wbridge5 has opener rebid 2♣ with 3 clubs.
Flat weak raise
Responder aims to sign off in 2M.
With flat 6 HCP, simple support may lead to disastrous 1M - 2M - 3m - 3M. Since 2M is usually the best contract and 1NT is no worse than 3M, Wbridge5 bids 1NT and counts on opener not passing.
Flat limit raise
Responder invites a minimum opener in the next round.
The special 2NT enforces a major fit and never results in a notrump contract. The 1NT lets opener reconsider notrump contracts.
When does opener pass
As usual, opener passes when no bid describes. However, opener tries hard to bid, so there are only few hands left for the pass.
- Minimum balanced hands with doubleton clubs: The other 2/3 balanced hands are safely biddable.
- Flannery opening hands with no biddable minor: These 4=5=2=2 and 4=5=3=1 hands are inherently hard to bid.
Opener’s rebids
Choice of strain
- Notrump vs suit: Major > notrump > minor
- Original suit vs side suit: 7-card original suit > 4-card side suit > 6-card original suit > 3-card 2♣
After 1♥ - 1NT
Opener rebids by the choice of strain above. With 3 clubs, opener bids 2♣ rather than passing.
| 1♥ - 1NT - | |
|---|---|
| 2♣ | 13–18, 3+♣ |
| 2♦ | 13–18, 4+♦ |
| 2♥ | 13–16, 6+♥ |
| 2♠ | 18–21, 4+♠ |
| 2NT | 17 HCP, no singleton or void |
| 3♣♦ | 19–21, 4+# |
| 3♥ | 16–20, 6+♥ |
| 3NT | 18–21 HCP, no singleton or void |
| 4♥ | 16–19, 7+♥ |
After 1♠ - 1NT
Over 1♠, opener can show either red suit at the 2-level.
| 1♠ - 1NT - | |
|---|---|
| 2♣ | 13–18, 3+♣ |
| 2♦♥ | 13–18, 4+# |
| 2♠ | 13–16, 6+♠ |
| 2NT | 17 HCP, no singleton or void |
| 3♣♦♥ | 19–21, 4+# |
| 3♠ | 16–20, 6+♠ |
| 3NT | 18–21 HCP, no singleton or void |
Second responses to a 1♠ opener
These 1♠ continuations are mentioned first to derive 1♥ counterparts because this way is easier than vice versa. Both bids in 1♠ - 1NT contain more shapes than in 1♥ - 1NT. Derivation of 1♥ rules from 1♠ ones is simple generalization except opener’s reverse.
After 1♠ - 1NT - 2♣
A new suit is constructive. A jump to 3♠ is a flat limit raise.
| 1♠ - 1NT - 2♣ - | |
|---|---|
| 2♦♥ | CONST, 6+# or (8–11 HCP, 5=#) |
| 2♠ | Preference, usually 2–3♠ |
| 2NT | INV, 9–11 HCP |
| 3♣ | INV, 9–11, 5+♣ |
| 3♠ | Flat LIM, 11 HCP, 3=♠, 4-3-3 side suits |
After 1♠ - 1NT - 2♦
Responder can still show hearts, or a long club suit at the 3-level.
| 1♠ - 1NT - 2♦ - | |
|---|---|
| 2♥ | CONST, 6+♥ or (8–11 HCP, 5=♥) |
| 2♠ | Preference, usually 2–3♠ |
| 2NT | INV, 9–11 HCP |
| 3♣ | 6+♣ |
| 3♦ | INV, 9–11, 4+♦ |
| 3♠ | Flat LIM, 11 HCP, 3=♠, 4-3-3 side suits |
After 1♠ - 1NT - 2♥
A minor at the 3-level shows a long suit.
| 1♠ - 1NT - 2♥ - | |
|---|---|
| 2♠ | Preference, usually 2–3♠ |
| 2NT | INV, 9–11 HCP |
| 3♣♦ | 6+# |
| 3♥ | INV, 9–11, 4+♥ |
| 3♠ | Flat LIM, 11 HCP, 3=♠, 4-3-3 side suits |
After 1♠ - 1NT - 2♠
Opener has shown 6+ spades, so responder raises with only 2–3 cards.
| 1♠ - 1NT - 2♠ - | |
|---|---|
| 2NT | INV, 9–11 HCP, 0–2♠ |
| 3♣♦♥ | Intolerance to 2♠, 6+# |
| 3♠ | INV, 9–11, 2–3♠ |
Second responses to a 1♥ opener
Most responses can be deduced from 1♠ continuations. This section lists only discrepancies. There are 2 sources of discrepancies, both related 2♠.
- Opener has reverse 2♠.
- Responder denied spades, which makes 2♠ good for a forcing convention.
Probing Wbridge5 5.12 shows that a ♠ stopper here is the ace or king.
After 1♥ - 1NT - 2♣
| 1♥ - 1NT - 2♣ - | |
|---|---|
| 2♠! | Super INV, 9–11 HCP, 5+♣, UNBAL, ♠ stopper |
After 1♥ - 1NT - 2♦
| 1♥ - 1NT - 2♦ - | |
|---|---|
| 2♠! | Super INV, 9–11 HCP, 4+♦, UNBAL, ♠ stopper |
After 1♥ - 1NT - 2♥
| 1♥ - 1NT - 2♥ - | |
|---|---|
| 2♠! | Super INV, 9–11 HCP, 2+♥, BAL, ♠ stopper |
Comparison to other 1NT treatments
Wbridge5’s 1NT is semiforcing in a strict sense: after a minimum opening, the 2♣ rebid is more frequent than pass. After an American semiforcing 1NT, pass is still the most frequent call.
The following is analysis after a minimum opening.
| Nonforcing | Wbridge5 | Forcing | |
|---|---|---|---|
| Pass | 35.3% | 16.4% | - |
| 2♣ | 20.3% | 39.2% | 44.5% |
| 2♦ | 20.9% | 32.0% | |
| 2♥ | 23.5% | ||
| Nonforcing | Wbridge5 | Forcing | |
|---|---|---|---|
| Pass | 22.5% | 7.5% | - |
| 2♣ | 18.9% | 33.9% | |
| 2♦ | 19.5% | 27.0% | |
| 2♥ | 20.1% | ||
| 2♠ | 19.0% | ||
Not probed
- The flat raise with 6 HCP: 4 random boards for an unpassed responder, where the flat 11 HCP raise had 300 targeted boards.
- Responder’s second call after opener’s 2NT, a 3-level rebid, or the reverse 1♥ - 1NT - 2♠.
- Opener’s rebids after a passed responder’s 1NT.
- Either side’s calls when the opponents double or bid after 1M - 1NT.