North opens 1♠.

South can respond with 2♥ with the possibility of rebidding if needed.

North has a choice between 2 and 3♠. Normally you need 16+ HCPs and a 6 card suit. Here you have 15 HCPs, but your shape 6/4 which is often powerful and players often say 6/4 bid more!

Over 3♠ south knows they have a 8 card fit so many will bid 4♠ s which with best play should go off.

Some souths may bid 4♥ which is a superior contract on the hope that north has at least 1 ♥ . Here they are superb and they find a superior contract. A 7/0 ♥ fit, with the 7♥ s in the weak hand is probably not too bad.

West opens with 1♦ .

East bids 1♥  which gets raised to 2♥  by west.

North may double and south bids 3♣ and East will bid 3♥  which goes off.

North's double is risky as he has no support for clubs and they could find a bad vulnerable fit, here it works, but statistically it is unlikely that south will have more than 4 or 5 clubs. North won't like passing over 2♥ s that makes.

An alternative bidding sequence is that south opens a pre-emptive 3♣ which is very (too) weak, particularly in position 2 and vulnerable. In postions 1 and 3 you can be more reckless as the opposition are likely to have the HCPs.

North will have a decision over souths 3♣  opener, to pass or punt with 3NT. With a singleton ♣ he will have problems entering the dummy, but he does have 17 HCPs. Many will bid 3NT but it is risky.

South opens the lowest of the two 4 card suits.

North bids the lower of his 4 card suits.

South bids 1NT to show balanced 15-16 HCPs.

North has an easy raise to 3NT with a combined minimum of 27 HCPs.

East opens with 2NT with a very balanced 20-22 HCPs.

West bids 3♣ stayman.

East responds 3♥ showing 4 or 5♥ s.

West raises to 4♥ s which makes.

East opens 2NT showing 20-22 HCPs.

West has a good 10 HCPs so can invite 6NT by bidding a quantitive 4NT.

East has a good source of tricks in ♠ s so accepts the transfer by bidding 6NT.

Most souths will lease the K♣ s, this however makes it easy for East who knows this lead is from K and Q ♣ s. So he can win the lead and lead a low club towards the J♣ which becomes the 12th trick. 

If a ♣ is not led, East will fall back by leading a ♦ hoping that ♦ s are 3/3 and his 4th ♦ becomes his 12th trick.

West opens 1♠ .

East is not strong enough in HCPs to bid 2♥ s so bids 1NT.

West jumps to 3♠ s with 16HCPs and 6♠ s.

East needs to recognise the misfit and pass 3♠ that goes 2 off due to the poor finesse positions.

North has an easy 1♠ with a ♥ rebid to come to show 5/4 shape.

East has a poor suit but may compete with 2♦ .

Some souths may support 1♠ by bidding 2♠ with 3 card support in a competitive auction. Many souths will pass to see what happens.

West will support ♦ s. North may compete by bidding 3♥ s.

East can bid 4♦ which will be passed out.

South opens 1NT with balanced 12-14 HCPs.

North transfers to ♥ s by bidding 2♦ s that after the transfer to 2♥ is passed out unless East does a very risky at this vulnerability with 2♠ s.

East opens with weak 2♠s with  5-9 HCPs and 6 ♠ s.

Not a perfect double with only 3♥  but wiht 16HCPs south should double.

North has a difficult decision, whether to bid 3♣ or 3NT with only one stopper. Here 3NT is the winning decision.