Albert Einstein said, “The grand aim of all science is to cover the greatest number of empirical facts by logical deduction from the smallest number of hypotheses or axioms.”

That applies at the bridge table. Players must make deductions, often with incomplete data.

In yesterday’s column featuring this deal, South was in four spades. He learned that West, who passed as dealer, held the club queen-jack (from his opening lead), the spade queen (after drawing two rounds of trumps) and the heart ace (from playing on that suit before touching diamonds). So, deducing diamonds wasn’t difficult.

Today, it is harder in four hearts after West leads his singleton spade queen. How should South plan the play?

In the auction, after North correctly rebid two spades, South moved with three hearts, aware that North might have only three spades and five (or six!) hearts. Then North raised to four hearts, thinking that the 4-4 fit would be preferable to the 5-3 (which is typically the case).

South, believing it much more likely that West had led a singleton than from Q-J- 10, won with his spade king and played on trumps. West took the second round and shifted to a low diamond.

Now the contract was on the line. If declarer misguessed, he would lose one heart, two diamonds and one spade ruff. Note that South did not know about West’s club honors. Still, leading a singleton when holding both aces would be unappealing – where would partner’s entry be? So declarer played dummy’s diamond deuce and made his contract.