OBVIOUS SHIFT PRINCIPLE
From A Switch in Time by Pamela and Matthew Granovetter

When is the Obvious Shift Principle Applied:

At Trick 1, partner of opening leader compares the led suit and obvious shift suit. Encouragement, upside-down or standard, denies tolerance for the obvious shift suit. Discouragement actively confirms tolerance for the obvious shift suit. This applies whether opening leader will maintain the lead or not.

Rules for Identifying the Obvious Shift suit, in order of priority:

Negatives:

The Obvious Shift cannot be the suit led.

The Obvious Shift is never trumps.

The Obvious Shift is never a suit headed by the A-K-Q or four of the top five honors.

The Obvious Shift in a suit contract is never dummy's singleton or void.

The Obvious Shift is never a natural suit bid by declarer.

Positives:

The opening leader's bid suit is the Obvious Shift:

If the opening leader has not bid a suit, the leader's partner's bid suit is the Obvious Shift

If both defenders have bid suits and the opening leader starts with an unbid suit, look at the suits and choose one of them by applying the rules below.

When the defense has bid two suits or when the defense has not bid any suits:

Against a suit contract, a three-card suit headed by at most one honor, Ace, King, Queen, Jack, Ten, is the Obvious Shift.

Against No Trump, dummy's shortest suit is the Obvious Shift, even a strong holding asuch as Ace-King doubleton.

When there is no weak three-card suit, the shortest suit is the Obvious Shift. But against a suit contract, this cannot be a singleton or void.

When there are two equal length suits, either of which might be the Obvious Shift, look at the number of honors. The suit with fewer honors is the Obvious Shift. If the suits have an equal number of honors, the lower-ranking suit is arbitrarily deemed to be the Obvious Shift.

 

Implementation Details:

Requirements for Encouragement in Obvious Shift suit if suit is:

1. Jxx or weaker : the Ace or King, or Queen vs. No Trump

2. Qxx : the Ace or King

3. Kxx : the Ace or Queen

4. Axx : the King or Queen

To Call for an Unusual Switch:

Play an unusual honor card. However, opposite a lead from the top of an honor sequence, when dummy does not have a singleton, vs. a trump suit, an unusual honor shows the top of the next lowest sequence, to allow an underlead.

 

With No Real Preference:

In general, this common situation is handled by making the least costly preference. This should be accounted for by opening leader, in the context of the hand.

Sometimes, one can, say, with 1082, under the Ace, play the 8, denying tolerance for obvious shift, then follow with the Ten, denying a doubleton. This denies encouragement for both the led suit and the Obvious Shift suit, so this is the way to show either general indifference or perhaps encouragement for a 3rd reasonable suit.

 

General Carding Scheme:

Attitude, in combination with Obvious Shift, is played only:

When following suit to the first time to partner's lead

When we discard

Count is used only in five specific instances:

with a doubleton to get a ruff after an A-K lead

at the six-level after a King lead

against no-trump after an Ace lead, or King, if you do it that way

helping partner to hold up and Ace or King

when cashing out and the high cards are known

Suit Preference:

We use suit preference at all other times: e.g. trumps, following mindlessly, etc.

Suit Preference with 3 suits

Eliminate one, usually the strongest, and give suit preference for the other two

 

 

If you wish to include this feature, or any other feature, of the game of bridge in your partnership agreement, then please make certain that the concept is understood by both partners. Be aware whether or not the feature is alertable or not and whether an announcement should or must be made. Check with the governing body and/or the bridge district and/or the bridge unit prior to the game to establish the guidelines applied. Please include the particular feature on your convention card in order that your opponents are also aware of this feature during the bidding process, since this information must be made known to them according to the Laws of Duplicate Contract Bridge. We do not always include the procedure regarding Alerts and/or Announcements, since these regulations are changed and revised during time by the governing body. It is our intention only to present the information as concisely and as accurately as possible.

 

 

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