Competition Problem 187
leads the ♠10
to South's contract of five spades.
Successful solvers: Jim Berry, Sebastian Nowacki, A.V. Ramana Rao, Rajeswar Tewari, Andries van der Vegt, Dave Wiltshire. These solvers were almost unanimous in suggesting DR4 but I'm adding a point because several submissions failed on part (b), typically falling into the trap mentioned below.
In both cases North wins the first trick and leads a club, South playing the ♣J if and only if East plays the ♣10, thus keeping East off the lead. West does best to switch to a heart.
(a) South wins as cheaply as possible (assume with the ♥J) and loses another club to West. North wins the heart return with the ♥A, South dropping the ♥K, and gives South a club ruff. Three rounds of trumps, South discarding a diamond, now start a repeating squeeze on West, allowing declarer to win the next heart with the ♥9. Declarer gets an extra winner in the suit West unguards and that winner repeats the squeeze.
(b) With the ♥A and ♥K swapped, if plays follows as in (a), then provided that East plays the ♥10 on the first round of hearts North cannot win both of the next two heart tricks and the contract fails. So South tries winning the first heart with the ♥A instead of the ♥J, and will obviously succeed if West continues hearts. But on winning the second club West rises to the occasion by returning the ♦K! Now the hearts are blocked as before and although South has been given a second diamond trick there is no heart-club squeeze to follow because North has to let go of a menace if South cashes the ♦Q.
Trap: In (b), a low diamond from West instead of the ♦K doesn't work. South wins as cheaply as possible and now has various routes to an ending such as this, with South on lead:
Three rounds of trumps squeeze West in the red suits, South's ♥8 being an entry to the ♦Q.
Hugh Darwen, 2020