Calculate carefully beta2.0

This is another defense problem in our weekly online training on 5th Feb, 2018.

Board 3
Vul: E-W
Dealer: South

    North     East     South     West
                                 1♠          X
     2♠           3♣       4♠         AP

Lead: ♢A

Trick     North     East     South     West
   1         ♢3           ♢2        ♢8       ♢A
   2                                                   ?

You lead ♢A and your partner follows ♢2. How to defend? Would you continue to play ♢ or play a small ♣ what your partner has bidden or draw a trump as a negative defense?

You have to consider several questions as followings:
Q1: Where are the 4 winners?
Q2: Who will hold singleton ♢, your partner or the declarer?
Q3: If the declarer holds 3♢, will losers be discard at once?
Q4: Is it necessary to play through ♣ immediately? Could the loser in ♣ be discard?

Your partner bids 3♣, indicating that barely will he hold 4♡, otherwise he may bid X instead of 3♣. It is obvious that the loser in ♣ couldn't be discard at once and the declarer holds long heart. So it is unnecessary to play through ♣ now. So continuing to play ♢ or playing ♡ becomes the main question. If your partner holds singleton ♢ and the declarer holds singleton ♣A, the distribution of the declarer will be 5♠, 4♡, 3♢ and 1♣, where is the entry to dummy to discard the loser in ♢. Your partner will not bid 3♣ in such vulnerability if he holds 3 small ♠ and 6 cards ♣ with QJ only. All in all, even if the declarer holds 3♢, the losers in ♢ always exist. If the declarer holds singleton ♢ and 5 small hearts, a ruff in ♡ is the only way to defeat the contract. Even if the declarer holds ♡A, you could still play through ♣ or draw ♢ by winning with the ♡K. Playing ♡ in the second trick is an unexpected but reasonable coup after carefully calculating.

The full deal:
Board 3
Vul: E-W
Dealer: South

Fu said that East should X at last, which would greatly reduce the difficulty of defense.