[polarmatt]

dealer is east. vuln: E-W
what does vuln E-W mean

East has

♠K Q 8 7
♥A K 4
♦Q 10 8
♣Q 7 5

What should east do? should he/she bid 1NT since east has 16 points and has a balanced hand 4-3-3-3?

South has

♠4 2
♥Q 7 6 5 3 2
♦K J
♣8 6 2

What should south do and why?

[hrothgar]

Vulnerable means that the stakes are higher for this hand.
You get a larger bonus if you make a game or slam, BUT the penalties for going down are larger as well.

Playing a strong NT system, East should certainly bid 1NT
West should respond by showing that he has a long heart suit, which will be a good source of tricks.

West probably won't try for game because even with that nice six card suit it will be hard to make 10 tricks with such a weak hand.

A typical auction would be

1N - 2D
2H - P

Where the 2D bid is a transfer showing 5+ Hearts

If you really wanted to be greedy, you might try

1N - 2D
2H - 3H
P

[manudude03]

When a side is vulnerable, it means that they score more points for making certain milestones, those being game, small slam and grand slam (and while rare, also scores more for overtricks on [re]doubled contracts). On the flipside, it also means they lose more points if they go down in their contract.

There are a large variety of bidding systems out there, and what you should do on a given hand often depends on your agreements. Online, the most common system includes a 15-17 NT and 5 card majors. Here, you would open 1NT because you have a balanced hand (no more than 1 doubleton) and your hand is in the range of 15 to 17 HCP.

I would highly recommend passing on the second hand, though you will get people who think it is worth bidding on. Generally speaking, you want your points to be inside your long suits.

hrothgar, on 2018-March-02, 07:35, said:

West should respond by showing that he has a long heart suit, which will be a good source of tricks.

West probably won't try for game because even with that nice six card suit it will be hard to make 10 tricks with such a weak hand.

I would agree if the second hand was the West hand, but the OP says it is the South hand.

[polarmatt]

hrothgar, on 2018-March-02, 07:35, said:

If you really wanted to be greedy, you might try

1N - 2D
2H - 3H
P

why bid 3H and then pass when the point of it is to prevent opponents from seeing the cards of the openers hand which is stronger?

[manudude03]

polarmatt, on 2018-March-02, 08:21, said:

why bid 3H and then pass when the point of it is to prevent opponents from seeing the cards of the openers hand which is stronger?

The declarer is the hand that first mentions the trump suit for their side. As the stronger hand bid hearts first, the stronger hand is hidden either way.

[rmnka447]

Vulnerability has to do with the method of scoring used in Contract Bridge. You score points toward game and rubber only for the value of the final contract bid. When a side accumulates 100+ points in contracts made before their opponents, then they've scored a game. Major suit contracts are worth 30 points a trick over 6 tricks, minor suit contracts are worth 20 points a trick over 6, and no trump is worth 40 points for the first trick over 6 and 30 points a trick after that. The standard rubber bridge score sheet segregates points scored for the contract and any other points won on a hand.

So if you bid and make 4 ♥/♠ (4x30), 5 ♣/♦ (5x20), or 3 NT (40+2x30), you score 100+ for the contract and win a game. But if you, say, bid 3 ♠ and made 4, you would only score 3 ♠ (3x30) which is 90 points toward game and play for the game would continue in rubber bridge. The additional 30 points for the over trick would be reflected elsewhere on the score sheet.

You need to win 2 games before your opponents to score a rubber. If you have already scored a game, you are said to be vulnerable. The rubber bonus for winning a second game before your opponents is larger than if you win the second game after both sides have won a game toward rubber. The penalty for going set vulnerable are also higher. Slam bonuses are also increased if you are vulnerable.

In duplicate bridge, this is reflected by increased game bonuses for vulnerable games versus non-vulnerable games and low part score bonus for non-game bids. Game bonuses are +300 non-vulnerable and +500 vulnerable with part score bonuses +50. 4 ♠ making scores +420 non-vulnerable and +620 vulnerable, while 3 ♠ making 4 only scores 170 regardless of vulnerability.