A New Approach to Double Clash Squeeze by Xiaobo Zhang Riverside, New Jersey October, 2002

Transcription

1 A New Approach to Double Clash Squeeze by Xiaobo Zhang Riverside, New Jersey October, 2002 Introduction: A basic rule in double squeeze is that the B threat, guarded by both opponents, must be accompanied by an entry in its own suit. As the result, a basic rule in compound squeeze, where each opponents guards two suits and only one guard a third, is that each of two doubly guarded (ambiguous) threats must be accompanied by an entry in its own suit [See Reference (1).] If both double squeeze or compound squeeze will fail owing to lack of entry or wrong entry position in the B suit or in one of the two doubly guarded suits, a double guard squeeze or double clash squeeze provides additional chances when some extra conditions are met. A double guard squeeze requires a middle card accompanied with top winner in a second doubly guarded suit while a double clash squeeze requires clash threats (described below) in either a second doubly guarded suit or in a singly guarded suit when there is an extra side entry. Double squeeze, compound squeeze, and guard squeeze are all discussed thoroughly by Clyde E. Love in Reference (1). Clash squeeze was named and analyzed by Chien- Hwa Wang with a long series of articles in Bridge Magazine and later summarized in Reference 2. However, Dr. Wang did not mention compound squeeze, hence did not discuss the relationship between the clash squeeze and the compound squeeze. Moreover, it is very hard for bridge players to master double clash squeeze using the classification of non-simultaneous and simultaneous double clash squeeze.

2 This paper takes a new approach to double clash squeeze, emphasizing the entry conditions and the relationship between double clash squeeze and either compound squeeze or, in rare cases, double squeeze. I hope that it will be much easier for an advanced player to understand the double clash squeeze under this approach. Readers are strongly advised first to have a thorough understanding of double squeeze and compound squeeze. The Vocabulary of Double Clash Squeeze: There are two forms of clash threats: basic and extended. Basic clash threat: A2 K(3) J9 Q Extended clash threat: A52 KJ(3) 987 K10 In the basic form, West must keep his king to guard the queen, and East must hold his jack-nine in case West is forced to bare his king. The singleton king is called a clash stopper and the jack-nine is called a weak stopper; the queen is the clash threat against West, and North's deuce is the weak threat against East. In the extended form, one top winners in each hand (the ace and king) are required, as they will be needed as entries. Here, West must keep his queen-jack and East his nineeight-seven in case West is forced to discard down to a doubleton. The queen-jack is a clash stopper, the nine-eight-seven is a weak stopper, the ten is a clash threat against West, and the five is a weak threat against East. Both a clash stopper and a weak

3 stopper in the clash suit are semi-stoppers; a clash stopper accompanied by a low card is a full stopper. A basic threat is the threat guarded by only one opponent, with the threat sitting over the stopper. Both a basic threat and a clash threat are required for a double clash squeeze. A split threat is the one that is not accompanied by entry in its own hand but faces a winner, a split entry, in the opposite hand. An unaccompanied entry opposite a split threat is a stiff split entry. A stiff split entry will be served as side entry in some double clash squeezes. In this example, the jack is a split threat and the ace is a stiff split entry. A Q8 K9 J3 Mechanism of the Double Clash Squeeze: The double clash squeeze is the variant of the compound squeeze (or, in rare cases, of the double squeeze). Assume declarer has all the tricks but one but has either no entry or a stiff split entry in a doubly guarded suit. In such layouts, an ordinary compound squeeze will fail, because the opponent with the basic stopper can afford to give up his stopper in the doubly guarded suit where declarer has ordinary entries (while his partner can discard from the basic suit). Declarer's entry position is then insufficient to execute any squeeze. However, when there is also a clash threat in either the doubly guarded suit with ordinary entry or the suit with basic threat, a double clash squeeze will succeed, because the opponent with the clash stopper can not afford to weaken his clash stopper. In effect, the clash stopper is the extra "busy" card that the opponent must keep, and, ultimately, both defenders will be squeezed. When declarer has at least one entry in the suit with basic threat, a double clash squeezes is non-simultaneous that the defenders will be squeezed on different tricks. In rare cases where declarer has no entry in basic suit, a double clash squeezes is simultaneous that the defenders will be squeezed in the same time on last free winner. Scenario A: Clash Threat in the Doubly Guarded Suit with Ordinary Entry. Let us name the suit with free winners (and no threats) the free suit, the suit with the basic threat the basic suit, the suit with the clash threat the clash suit, and the remaining suit (which is doubly guarded) the fourth suit. In a double clash squeeze,

4 there are four threats: basic threat in basic suit, clash threat and weak threat in clash suit, ambiguous threat in fourth suit. If the opponent with the basic stopper also has the clash stopper along with the stopper in fourth suit, he falls victim to a clash squeeze when he is triple squeezed on the last free winner. Multiple entries are required in order to be able to reach all of declarer's potential winners. (1) The hand with weak threat in clash suit must have an entry in either the basic suit or the fourth suit for cashing its top winner in case the triply-squeezed opponent gives up his clash stopper. (2) The hand with the ambiguous threat must have an entry in either the basic suit or the clash suit for cashing an established winner in the fourth suit. If there is no entry in the fourth suit, then at least one entry is required in basic suit. (3) If there is no entry in the basic suit, then the hand with the basic threat must have a side entry, in case the triple-squeezed opponent yields his basic stopper. In order to meet all of these requirements, each hand must have at least one side entry in addition to any top winner in clash suit. In Scenario A, the double clash squeeze consists three steps: (1) The next-to-last free winner triply squeezes the defender with the basic stopper, the stopper in fourth suit, and a full stopper in the clash suit. Yielding the basic stopper gives declarer an extra trick immediately. Giving up a stopper in the fourth suit will let declarer establish an ordinary double squeeze, one of Type R in Love's terminology. Should the defender instead bare his clash stopper, a double squeeze of either Love's Type B or Love's Type R will ensue except that the B-suit has no entry or has a stiff split entry which would lead to a double clash squeeze (see step 2 & 3). (2) The last free winner will re-triple-squeeze the same opponent with clash stopper, basic stopper, and the stopper in the fourth suit. At double-dummy, he can do no better than to yield his stopper in the fourth suit. In such cases, the basic threat (L-threat in Love's terminology) is discarded, positionally, after the triple-squeeze keeps a guard in the basic suit. (3) If declarer has one of more top winners in the basic suit, when the last basicsuit winner is cashed, a simple squeeze occurs against the other opponent who holds weak stopper in the clash suit and the stopper in fourth suit. When declarer has no winner in basic suit, a simple squeeze against that opponent will be established when last free winner is cashed. Scenario B: Clash Threat in the Basic Suit. Here, let's define a doubly guarded suit with no entry or with a stiff split entry as Suit 0, and a doubly guarded suit with an ordinary entry as Suit 1. If the opponent with the basic stopper does not have any card higher than declarer s clash threat in the basic suit, a double clash squeeze will succeed, because both opponents will be triple squeezed. Notice that both opponents have to guard three suits, so the squeeze is hexagonal. For this to come to pass, each of declarer's hands must have at least one entry besides any top winner in the basic suit.

5 A Scenario B double clash squeeze also consists of three steps: (1) The next-to-last free winner will triple squeeze the opponent who has the basic stopper. Yielding his basic stopper will give declarer an extra trick at once; giving up the stopper in Suit 0 will let declarer establish an ordinary (Type R) double squeeze; giving up the stopper in Suit 1 will permit a double squeeze (or Type B or Type R) except that the B-suit has no entry or has only a split entry which would lead to a double clash squeeze (see step 2 & 3). (2) When the last free winner is led, the opponent with a clash stopper in the basic suit will be clash squeezed, forced to give up his guard in Suit 0. Declarer discards the threat in Suit 1 positionally when it has not been established. (3) When declarer cashes his winner(s) in Suit 1, the victim who was squeezed at step 1 will be re-squeezed between the basic suit and Suit 0. Types of Double Clash Squeeze For definiteness, assume that South is the hand with one threat only. In some situations, both opponents can be clash squeezed. However, it is much more common to clash squeeze West and simple squeeze East. For the reverse to be possible--east to be clash squeezed and West to be simple squeezed, extra requirements must be met. In my naming convention for types of double clash squeeze, the first character is either A (for Scenario A) or B (for Scenario B); the second character is either L or R, to indicate whether West (LHO) or East (RHO) will be clash squeezed; the third character is either 0 or 1, to indicate that declarer has no entry (0) or a stiff split entry (1) in a doublyguarded suit. Scenario A: Clash Threat in the Doubly Guarded Suit with Ordinary Entry The types of double clash squeeze where West is clashed are AL0 and AL1; the types where East is clashed are AR0 and AR1. Clash Squeeze Against West: West has the basic stopper, the clash stopper, and a fourth-suit stopper; North has the basic threat. If there is an accompanying entry in the basic suit, a restricted Type-L compound squeeze is present except that there is either no entry or a stiff split entry in the fourth suit. If there is no accompanying entry in the basic suit, a type R or type B1 double squeeze will be present except that the entry in the B-suit is a stiff split entry. Type AL0: No Entry in Fourth Suit A restricted Type-L compound squeeze is present except that there is no entry in fourth suit. It is necessary to have two top winners opposite the threat in either the basic suit or the clash suit, plus at least one entry in the basic suit. If South has a top winner without small card opposite in fourth suit, then the North hand can have enough room for the squeeze card (last free winner).

6 Example 1 A62 -- K43 K9 A Q65 J104 K Q Q A2 Here, South has ambiguous threat heart queen without entry. But he has two opposite top winners in the basic suit (diamonds) along with clash threat spade queen. The club king will force West to discard his last idle card, the spade nine. When the club ace is led, West is clash squeezed and must give up his heart-ace stopper in the fourth suit. North discards the basic threat (diamond three). East will be squeezed in majors when declarer cashes the diamond king-ace. Example 2 A62 -- K43 K9 A Q65 J104 K Q Q A2 Here North has ambiguous threat diamond deuce without entry. South has an entry in the basic suit, and both hands have a top winner in the clash suit. The club king will

7 force West to discard a heart, and the club ace will then clash squeeze him. North discards the basic threat (spade jack), and the spade ace will squeeze East between the red suits. Type AL1: Stiff Split Entry in Fourth Suit If there is at least one ordinary entry in the basic suit, and there are two winners opposite the threat in either the basic suit or the clash suit, then the stiff winner in the fourth suit can be cashed first to simplify the play into a Type AL0 double clash squeeze. If there is only one entry in both the basic suit and the clash suit, then a restricted Type-L compound squeeze is present except that the entry in the fourth suit is a stiff split entry. The hand with the ambiguous threat must have a side entry to enable declarer to reach a potential winner in the fourth suit. The stiff split entry in the fourth suit also serves as the required entry in case West yields his clash stopper. The stiff winner in the fourth suit will be cashed (a Vienna Coup) after the clash squeeze when West keeps both basic and clash stoppers. Then, East will be squeezed between the fourth suit and the clash suit when declarer cashes his top winner in basic suit. Example 3 Q J2 AJ3 K9 Q3 KQ J10 K4 A2 A 2 Here, South has stiff heart ace in the fourth suit, and there is only one entry in both the basic and clash suits. West is clash squeezed when last free winner is cashed. If West keeps his diamond king-queen and spade king, North will discard the diamond jackthree; then, the heart ace will be cashed (Vienna Coup) and East will be squeezed between the majors by the diamond ace.

8 Example 4 A2 A Q3 2 Q7 Q4 K5 98 K4 10 J5 A Here, North has stiff split entry heart ace in the fourth suit. South is required to have an entry in the basic suit (diamond ace). West is clash squeezed when the last free winner is cashed. The heart ace must be cashed before the diamond ace (Vienna Coup). East will be squeezed between the majors when declarer cashes the diamond ace. If there is no entry in the basic suit, then extended clash threats are required besides stiff split entry in the fourth suit for necessary communication. The next-to-last free winner will triple squeeze West. If he gives up his stopper in the fourth suit, declare can cash his stiff winner in the fourth suit to form a type R or type B1 double squeeze. If he discards a small card in clash suit, he will be clash squeezed and his partner will be simple squeezed when the last free winner is cashed. Also, a Vienna Coup will be required after the clash squeeze has matured. Example 5 K10 J2 J2 QJ Q3 K9 876 K4 8

9 A32 A -- Here, South has stiff split entry heart ace in the fourth suit, but there is no entry in the basic suit. Fortunately, declare has expended clash threats in spades. When the nextto-last winner is cashed, West is triple squeezed. If he throws his H3 away, a type B1 double squeeze will be followed once HA is cashed. The best he can do is to discard his S9. When the last free winner is cashed, West is clash squeezed and East is simple squeezed between the majors. The heart ace will be cashed as a Vienna Coup. Example 6 A32 A2 Q QJ Q3 K5 987 K4 8 K10 J5 -- Here, North must bare his heart ace on the next-to-last free winner, because no hand can hold all three threats in a double squeeze. West has choice to let declare play type R double squeeze or clash double squeeze. The heart ace will be cashed as a Vienna Coup after the clash squeeze. Clash Squeeze Against East: East has the basic stopper, the clash stopper and a fourth-suit stopper; South has the basic threat. A Type-R compound squeeze is present except that there is either no entry or a stiff split entry in the fourth suit. For North to have room for an idle card to discard before East plays to last free winner, South must have an extra winner in either the basic suit or the fourth suit. North must have a top winner in the basic suit as a required side entry. East will be clash squeezed, forced to yield his stopper in fourth suit, and

10 West will be simple squeezed between the clash suit and the fourth suit. Either North or South might hold the squeeze card. Type AR0: No Entry in Fourth Suit. A restricted Type-R compound squeeze is present except that there is no entry in the fourth suit. North must have the fourth-suit threat and a weak threat in the clash suit. South must have two top winners in the basic suit. Hence, the basic suit must be equivalent to ace-low (or ace-low-low) opposite king-queen-low-low. East will be clash squeezed on the last free winner, and West will be simple squeezed when declarer cashes his top winners in the basic suit. Example 7 A2 J K Q3 6 Q6 K J AQ52 Here, North has fourth-suit threat heart jack without entry, but declarer has three top winners in the basic suit. East is clash squeezed when the club ace-king are cashed. Then, West will be squeezed between the major when declarer cashes the diamond king-queen-ace. Type AR1: Stiff Split Entry in Fourth Suit A Type-R compound squeeze is present except that the entry in the fourth suit is a stiff split entry. This layout is similar to Type AR0, except that South s stiff winner in the fourth suit can be used as one of the required entries, so that South can survive with only one top winner in basic suit. A Vienna Coup is required after the clash squeeze.

11 Example 8 A2 J2 K Q3 Q6 K4 J93 10 A Q52 This example is a modification of Example 7; the diamond ace is replaced by the heart ace and other adjustments made accordingly elsewhere. An unrestricted Type-R compound squeeze is present except that South has a stiff winner heart ace in the fourth suit. East will be clash squeezed when last free winner is cashed. The stiff heart ace will be unblocked as a Vienna Coup after the clash squeeze. West will be squeezed between the majors when declarer cashes his top winners in diamonds. Scenario B: Clash Threat in the Basic Suit In Scenario B, the squeeze is hexagonal since opponents have six guards. The types of double clash squeeze against West are BL0 and BL1. The only type of double clash squeeze against East is BR0. Clash Squeeze Against West: West has the clash stopper in basic suit plus the stoppers in other two suits. East has a weak stopper in the basic suit plus the stoppers in other two suits. North has the clash threat in basic suit, South the weak basic threat. A restricted Type-R compound squeeze is present except that there is no entry or a stiff split entry in Suit 0. Type BL0: No Entry in Suit 0. A restricted Type-R compound squeeze is present except that there is no entry in Suit 0. South must have an entry in Suit 1, and North must have an entry in either Suit 1 or the basic suit. East will be triple squeezed by the next-to-last free winner, and West will be clash squeezed on last free winner. Should West keep his clash stopper and guard in

12 Suit 0, North can afford to discard his threat in Suit 1. Then, East will be squeezed between the basic suit and Suit 0 when declarer cashes his top winners in Suit 1. Example K43 5 Q K QJ Q 6 A2 -- A2 Here, North has ambiguous threat heart deuce without entry, but both of declarer's hands have a top winner in Suit 1. East is triple squeezed when the club king is cashed, and West is clash squeezed when the club ace is cashed. East will be squeezed between the majors when declarer cashes his diamond ace-king. Example 10 K QJ K QJ Q A32 -- A2

13 This example is a modification of Example 9, with the diamond king exchanged with the spade king and the other hands changed accordingly, giving North an entry in the basic suit and South an entry in Suit 1. A Vienna Coup is required after the clash squeeze, and East will be squeezed between the majors when declarer cashes his diamond ace. Type BL1: Stiff Split Entry in Suit 0 A restricted Type-R compound squeeze is present except that there is a stiff split entry in Suit 0. No extra entry is necessary, but a Vienna Coup is required after clash squeeze. Example K4 5 Q K6 QJ 3 98 Q3 A2 A 2 Here, South has a stiff split entry heart ace in Suit 0. The heart ace must be cashed after the clash squeeze. East will be squeezed between the majors when declarer cashes the diamond king. Clash Squeeze Against East: East has the clash stopper in basic suit plus the stoppers in other two suits; West has a weak stopper in the basic suit plus the stoppers in other two suits. South has the clash threat in the basic suit, North the weak basic threat. A restricted Type-L compound squeeze is present except that there is no entry in Suit 0. In order to make room for North to have an idle card to discard before East is squeezed by the last free winner, South must have an extra winner in Suit 0.

14 Type BR0: No Entry in Suit 0 A restricted Type-L compound squeeze is present except that there is no entry in Suit 0. Two opposite top winners are required, in either the basic suit or the Suit 1. West will be triple squeezed on the next-to-last free winner, and East will be clash squeezed by the last free winner. The top winner in Suit 0 should be cashed after the clash squeeze, and when West keeps the clash stopper and a guard in Suit 0, North can afford to discard his threat in Suit 1. West will then be squeezed between the basic suit and Suit 0 when declarer cashes his winners in Suit 1. Example 12 A62 -- K Q3 QJ J6 QJ 3 K10 A2 2 Here, declarer has clash threat spade ten in the basic suit, along with two opposite top winners. North has an entry diamond king in Suit 1. Most importantly, South has an extra top winner (the heart ace) in Suit 0. The club king will force West to discard his stopper in diamonds, then the club ace will clash squeeze East to give up his stopper in hearts. North can pitch the diamond four when declarer cashes the heart ace after the clash squeeze. Then, when declarer cashes the diamond king, West will be squeezed between the majors. References: (1) Love, E. Clyde. Bridge Squeezes Complete. Dover Publications, Inc. New York Pages 53-81, (2) Wang, Chien-Hwa. The Squeeze at Bridge. Cadogan Bridge. London Pages