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 such 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 under lead.

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