A prism signaler normally uses
the trump suit to convey information about parity and identity of the single suit. At no
trump, the defenders may agree to designate declarer's trick source as a proxy trump suit.
Consider this grand warm-up
featuring powerful spades and a Minor Prism:
||Declarer wins the diamond king
opening lead with the ace. Next come the spade ace, a spade to the king, and a top spade.
Declarer discards a diamond on the third round. West started with four (even)
spades. West follows 4-5-2-9 in the proxy suit, to announce an odd single suit
4_5...2- clubs .
4-4-3-2 hand pattern
East must unguard clubs
or hearts when spades are continued from dummy:
||The Gerber sequence promised two
aces and a king with declarer. The weak no trump allows for the club queen or the heart
queen, not both. Which? Not the club queen. With it, three rounds of clubs would precede
the spade avalanche to activate potential squeezes.
So declarer is 2=4=3=4
with the king-queen fourth threat in hearts. East abandons clubs, holds hearts, and
defeats the grabby grand.
The full deal:
In a variation of the same
deal, South and West trade round threes. Declarer wins the diamond ace
and runs spades. West, holding four (even) spades, follows 2-4-5-9 in the proxy suit, announcing an odd single
suit 2_4...5- hearts.
Again, East must commit
in this position:
||The weak no trump rules out five
hearts (2=5=3=3). And West can defend single-handedly against five diamonds (2=3=5=3) by
keeping the diamond queen and a round queen-third on the side.
But West cannot
contribute to the defense when declarer's threat is in clubs (2=3=3=5.) So East keeps
clubs, abandons hearts and defeats the grand.
Consider this no trump deal
which features solid hearts, a Black Prism and a prism signal- the
distributionally correct guide to effective defense in a PC world:
West leads the
diamond eight, East plays the five, declarer wins with the ten; and runs hearts. East has
three (odd) hearts and follows
3-5-10, promising an odd single
Declarer started with two
diamonds and the king now stands alone. On the fourth heart, East discards a discouraging
spade. Unable to defend against an end play if declarer has the club queen, West places
that card with East. On the run of hearts West abandons clubs, reducing to:
always down one, tries to establish a spade trick before cashing the club ace...down two.
The full deal:
South and East trade minor suit
fours- a trade which strengthens declarer's diamond king. As compensation, East gets
declarer's spade queen in exchange for the spade ten. Rotisserie bridge.
wins West's diamond lead with the ten and runs hearts. This time East follows 5-3-10 with his three (odd) hearts, promising an even
single suit 5_3...10- spades.
variations of the six card position that the 'four triple three' notrump declarer may
reach after discarding on the run of hearts. With the lead in dummy, declarer needs
If Declarer's spade king and
diamond king remain guarded, West must also hold two cards in each of those suits. And,
West must hold two clubs, a second to protect against a strip of the suit thus ensuring
possession of an all important exit card. This defensive alignment works in
variation iii as well.
In all three variations if
declarer starts with the club ace from dummy, West plays the king. If declarer instead
starts a low club from dummy, East must pounce with the queen and play spades.
In the first variation declarer
with a known 3=3=3=4, reduces to two cards in each non-heart suit. Two tricks needed with
the lead in dummy:
Declarer's best start is a spade from dummy. But mere ham-fisted trick-grabbing by the defense limits this "no
threat" offense to the club ace.
Spade to the king and ace;
spade jack overtaken by the queen; then, the spade nine (diamond queen discard); any club
out -down one.
A more potent offense, in which
the 3=3=3=4 declarer hangs on to three spades, is still no match for a distributionally
informed defense. Two tricks needed with the lead in dummy:
with a spade from dummy to the eight, ten and jack. If West cashes the spade ace
immediately, a low club exit to dummy's ace allows declarer to end play West with a club
And continuing the club king
rather than a low club allows declarer to use East's club queen as a stepping-stone to the
So before playing the
spade ace, West plays the club king. If dummy wins, declarer gets no more tricks. If
declarer refuses the club king, West cashes the spade ace; then puts the dummy which now
lacks a club exit on play.
A third offensive scheme
featuring clubs with declarer rather than spades proves no match for prism signaling
distribution trackers. Two tricks needed with the lead in dummy:
A spade from
dummy, low, king, ace. Here, if West plays the club king, dummy wins and puts East on play
with a club. And, the defense must surrender a trick. So, rather than play the club king,
West can exit with the club deuce to defeat the contract.
Alternatively, after a
spade to the king and ace, an immediate spade jack squeezes a club from declarer and the
club king is once again effective. If East makes the ham-fisted
trick-grabbing overtake of the spade jack with the queen to cash the long spade, declarer
and West discard diamonds. And, East must be careful to exit with the club queen to defeat
When there are three single suit candidates,
identification requires ordered play of three spot cards. With only two single suit
candidates, a simpler identification technique is available.