These series of article were written by Eric Kokish and his wife Beverly Kraft.
Here are two declarer play problems:
(1)
 K Q 10 7 2  J 4 3 7 4 A Q 3
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Contract: 4 by West
Opening Lead: J
Note: Trumps are not 4-0.
(2)
| A Q 3 A Q 4 2 J 6 5 4 A 6
|
Contract: 6NT by West
Opening lead: 10
Solutions:
1) 4 is no worse than an even money proposition, depending on the location of the K. Is there anything better? You might try leading hearts toward the jack twice. If South holds the ace-king you might build a heart discard to pitch a diamond. Not too likely and this might easily lead to three heart losers and a diamond loser. The good news to brighten your Sunday is that 4$ cannot be defeated if you play it correctly. Win the K, draw trumps, play the A Q to discard the 2 from dummy, then play A, Q, giving up on the 50-50 finesse. Whoever wins the K will have to play a club or diamond, allowing you to discard a heart while ruffing in dummy, or will instead break the heart suit, in which case you will play second hand low and lose only two tricks in the suit.
(2) You have 11 top tricks in 6NT. A twelfth will be easy if hearts divide three-three, but you have an extra chance in diamonds. Win the spade lead in the East hand and lead a low diamond, following low from West. Win any return and play the A. If someone started with king-queen doubleton the J will be a surprise twelfth trick. Assuming that this miracle does not come to pass, run your remaining black winners, discarding diamonds from the West hand. The last black winner will force a fatal discard from either opponent if he started with at least four hearts and at least four diamonds. You don’t really need to know anything about squeeze technique to play this hand correctly. It will suffice to realize that you might make an extra trick in diamonds and to duck a round early without releasing the ace. After that, there is nothing more to the play than watching for diamond discards. If the 9 is not high, then your remaining chance lies in hearts. Either your fourth heart will be good, or it won’t.