[ArtK78]

kgr, on 2011-December-12, 07:04, said:

Jack 2.04 (old version) seems to always Pass iso bid 3NT in balancing.
But some additional notes:
- This was a Pairs Tournament I loaded, but if I look at the scoring options in Jack then I see:
- - Total Points
- - Rubber
- - Chicago : What is Chicago?
(So I'm not sure it knows MP's, or is that Chicago?)
- After the 3NT: Jack in North Passes when Opps are N-Vul and bids 4S when opps are Vuln. It seems that Jack assumes a better D-hand for 3D when West is Vuln and therefor bids 4S when opps are Vuln?

Chicago is four-deal bridge. Both sides are nonvul on the first hand, dealer's side is vul on the 2nd and 3rd hands, and both sides are vul on the fourth hand. The original version of Chicago is scored like rubber bridge, with part-scores carrying over from deal to deal (100 point bonus for a part score after 4 hands), but newer versions score each deal like duplicate bridge.

There is a variation of Chicago where the non-dealer's side is vul on the 2nd or 3rd hand. I forgot the reason for that variation.

[JLOGIC]

Non dealer is better than dealer being vul on hands 2 and 3 because it creates more action. You can be 3rd seat white/red! You can be first seat white/red and preempt!

[Zelandakh]

There is also a variant where you score 20 points for each HCP you hold less than the opps. I agree with Justin that the version where dealer is not vulnerable on boards 2 and 3 is much better than the original.

[phil_20686]

On the hand given it is not right to bid 4S over 3N. Partner may easily have just a good club suit and cashing tricks. He refused double for a reason. Either he has really good diamond stop or he has short in one major. Can easily imagine that Jack has difficulty simulating hands with condtions like "has a single stop with cashing clubs or a very good stop with softer values or has a poor stop but only because major shortage rules out dble".