[goffster]

http://tinyurl.com/lwjjz63

Under no circumstances should a defender *ever* cover the Spade jack when led from the board.
It can simply never be the right play.

[Antrax]

a) I assume you meant the ♠T.
b) It didn't matter.
c) Your bidding told E you have all the high cards it doesn't have, so from its perspective you don't need to ruff a club since you have the K.

[iandayre]

I don't really agree. Covering retains the power of your small Spade, forcing Declarer to play the suit 3 times to draw all the trumps. If you duck, the J holds, Declarer then cashes the A and goes about his business. Won't likely matter here but I have seen hands where it does.

I suppose some novice might fly with the A after a duck, but at any decent level it's not going to happen.

[goffster]

The reason it is wrong here is that with a *10* card combined holding, it is usually right to
play the ace.

GIB should realize there is a good possibility of a 10 card fit, and therefore there
is a guess in the suit.

[1eyedjack]

goffster, on 2015-February-01, 13:56, said:

The reason it is wrong here is that with a *10* card combined holding, it is usually right to
play the ace.

Why? He can't escape a trump loser whether he rises with the Ace or not. By running the Jack he guarantees that the trump losses are restricted to the single certain loser, where rising with the Ace risks losing two trumps on the layout shown.

[goffster]

Oops, you are right, I was confused

[1eyedjack]

That said, I agree that he should not cover. GIB assumes perfect play on the part of its opponent. It is not good at offering a losing option that would be inferior play but which costs nothing in the offering.