[GrahamJson]

Perhaps I have missed something here. We are missing the 54 of hearts and either east has them both or south does. They cannot be split. Others have invoked arguments about East having 13 cards etc. It seems to me that any such argument that applies to east could equally well apply to south. The only factor that can be taken into account is that as S has opened 1NT he must hold at least four honour cards, probably more. East may not hold any (the honours held by west and north will indicate how many east might hold). This leaves move vacant spaces for spot cards in East's hand compared with south. Hence east is more likely to hold the outstanding hearts than is south. Added to this is the factor that holding K542 of hearts S may have played the 5 or 4. This may not be the best strategy, but players don't always follow the best strategy.

[smerriman]

GrahamJson, on 2017-February-07, 05:18, said:

Others have invoked arguments about East having 13 cards etc. It seems to me that any such argument that applies to east could equally well apply to south.

It does, and leads to the same result. There isn't symmetry here, since you know East has 3 or 1, while South has 2 or 4.

[Phil]

Kaitlyn S, on 2017-February-06, 21:45, said:

I couldn't see how it could help to imply a doubleton. I do now. Thank you.

Its all good.

[jogs]

Kaitlyn S, on 2017-February-06, 21:45, said:

I couldn't see how it could help to imply a doubleton. I do now. Thank you.

You kept us in the dark on the play. Assuming imps(hate mps, it's a guessing game) when West gets in it is extremely unlikely E-W can beat 3NT unless South started with Kx. In imps playing with a pickup who may play small from xx, I would as West play the ace hoping to drop the king. It is only clearly wrong if and only if the heart king is South's ninth trick.