[karlson]

I have to admit Cascade's numbers are interesting and counterintuitive to me at least -- I would expect a 5-3 spade fit to play better reasonably often. What hand types are you considering?

However, if the alternative to a forcing 3♠ is simply 3N then we have to count 5-4 (and hell, even 5-5) fits as well, though those frequencies are probably small.

[karlson]

bd71, on Oct 7 2010, 12:58 PM, said:

Giving up the possibility of a part-score for more flexibility to find the right game or possibly a slam makes perfect sense.

Am now hoping folks help me try to more precisely define this forcing situation:

1. Narrow construction: any 3-level bid by us after (1x)-1N-(3x) is game-forcing.

2. Broad construction: after partner has shown a good hand with no clear suit preference (i.e. either TO X or NT overcall) and they have pre-empted to the 3-level, any 3-level bid by us is game-forcing.

Are either of these the optimal way of stating this principle? Something in-between? Something broader?

1. Yes, and the same for 1N-(3x). After 1N-(2x) you can play lebensohl or your other favorite convention but you should have some way to force with a major.

2. After a takeout double the situation is very different. Firstly you're guaranteed a fit in your 5-card suit, since partner should not have a doubleton (so you can jump to game more freely), and secondly, 3N is unlikely to be right unless you have a very strong holding in their suit since partner will rarely have a stopper. Finally, partner has shown less strength so game hands will become less frequent relative to partscore hands. All in all, I would definitely play 3M NF after (1x)-x-(3x) or the like.

[Cascade]

karlson, on Oct 8 2010, 10:25 PM, said:

I have to admit Cascade's numbers are interesting and counterintuitive to me at least -- I would expect a 5-3 spade fit to play better reasonably often. What hand types are you considering?

However, if the alternative to a forcing 3♠ is simply 3N then we have to count 5-4 (and hell, even 5-5) fits as well, though those frequencies are probably small.

Just any 5=3 fit no other constraints not imposed in the original problem.

Perhaps at MPs it is a little more necessary to find the 5=3 fit. However given the almost sure shortage in diamonds opposite a known stopper sometimes this shortage (or stopper) is wasted.

Assuming you play takeout doubles 5=4 fits are easily find by making a takeout double. If 3♠ is not forcing then there will be some swings if you bash 3NT without investigating a fit for your five-card major though.

The reality is that game force hands are infrequent on this sort of auction. Here are some frequencies (from simulation) :

0 33
1 98
2 190
3 522
4 1016
5 1411
6 1691
7 1628
8 1303
9 965
10 644
11 302
12 148
13 46
14 3
15 0

Obviously where you start to game force will depend on your distribution. However even if you game force on all 8 hcp (quite optimistic in my view) then forcing bids are only catering to about 1/3 of your hands (at the most as some will be suitable for 4♠ or 3NT or maybe a 2-suited bid). Whereas a range like 5-8 caters to nearly double that frequency.

Having looked in detail at 100 hands I am reasonably confident that there are gains available for a non-forcing approach:

1. Basically real game forcing values are very infrequent

2. Over a constructive non-forcing bid sometimes overcaller can raise with a good fit

The constraints for the above simulation were

1D opening

10-19 hcp - 10 counts needed a six-card suit or a five-five hand
not 15-17 balanced
open 1♦ with 4-4 in minors but not 3-3

1NT overcall balanced with a stopper

3♦ bidder had five diamonds and 0-7 hcp.