[Tryggolaf]

Recently I've switched from playing four card majors to five card majors. I open 1♣ with a doubleton (4432) and a trebleton (4333, 3433, 4423) as well. This change leads to some uncertainty about partner's club length when he opens 1♣, although experienced players have told me that most of the time the clubs are real (4+) and I should treat opponents' 1♣-openings with at least a doubleton as a real ♣ bid (for example, treating it as a real color for a take-out double). It would be interesting and handy to know the percentages behind the club length: how often does the 1♣ opener have exactly 2♣, 3♣, 4♣, 5♣, 6♣, 3+ ♣, 4+ ♣, 5+ ♣ (on the premise of a 1♣ opening with 2+♣)?

Another related question. Recently we've started playing a basic version of inverted minors: 1♣-2♣ (10+ and 4+♣). Over 2♣, stoppers are shown on the two-level and the bidding only becomes FG if someone bypasses both 2NT and 3♣. 1♣-3♣ is 6-9 and 5+♣ and every continuation asks for a stopper and is FG. How does the fact that I have switched to a short club opening affect my inverted minors?

[Vampyr]

You need to give your opening 1NT range (and your 2NT range even) before anyone can produce a calculation for you

[BillHiggin]

It does look like your 1♣ opening might be best described as "either unbalanced with 4+ clubs or balanced". This is why the notrump range is needed if we really want to determine the frequency of short club holdings. But, if you use that definition, then you may well find that all the worry about short club holdings evaporates as you focus on "where should we be going if opener has a balanced hand".

[Zelandakh]

BillHiggin, on 2014-July-30, 18:19, said:

"either unbalanced with 4+ clubs or balanced".

Not sure I agree with either side of this definition. On the unbalanced side we have to eliminate most hands with a high-ranking suit of equal length and on the balanced side we need to remove all hands with 4+ diamonds or a 5 card major. In the ACBL you could probably also describe it as 2+ clubs and natural. I await the day when I can bid 1m "naturally" with a void in the suit opened!

[fbuijsen]

With a 15-17 1NT and 20-22 2NT opening, the club suit will be a doubleton (4-4-3-2) roughly 3.5% of the time. I don't remember the numbers for how often it is a 3-card suit, but would guesstimate it is roughly 3 times as often, so about 10% (4-3-3-3, 3-4-3-3 and 4-4-2-3)

[rhm]

Zelandakh, on 2014-July-31, 02:38, said:

Not sure I agree with either side of this definition. On the unbalanced side we have to eliminate most hands with a high-ranking suit of equal length and on the balanced side we need to remove all hands with 4+ diamonds or a 5 card major. In the ACBL you could probably also describe it as 2+ clubs and natural. I await the day when I can bid 1m "naturally" with a void in the suit opened!

What he means is that if clubs are less than 4 cards the hand has to be balanced, not that all balanced hands are opened 1♣.

Rainer Herrmann

[rhm]

Tryggolaf, on 2014-July-30, 16:34, said:

Another related question. Recently we've started playing a basic version of inverted minors: 1♣-2♣ (10+ and 4+♣). Over 2♣, stoppers are shown on the two-level and the bidding only becomes FG if someone bypasses both 2NT and 3!C. 1♣-3♣ is 6-9 and 5+♣ and every continuation asks for a stopper and is FG. How does the fact that I have switched to a short club opening affect my inverted minors?

Disregarding the possibility that opener has 2 cards is in my opinion okay, but assuming more than 3 cards in clubs in opener's hand is problematic.
As a rule any direct club raise should show 5+ cards. This is useful information to both opener and responder and helps knowing when to play clubs and how high.
If responder is precisely 3♠=3♥=3♦=4♣ and unsuitable for a notrump bid, the roof won't always fall in if you respond 1♦ to 1♣.
When an opponent overcalls or preempts, responder might have to bid clubs based on only 4 cards if nothing else fits.

Rainer Herrmann

[PhilKing]

I hestitate to mention Bayes', but if we hold 5 clubs and 6-9 points, the chances that opener holds 2 clubs goes way up from the modest headline figure.

The first point is obvious: the presence 5 clubs in our hand reduces the odds that partner has club length. The second is more subtle: if partner has club length, there is a somewhat greater chance that RHO will have a hand that wishes to intervene.

So when you decide to jack it up with a raise to 3♣ on such hands, don't be surprised if partner continually shows with a balanced hand with two clubs. My experience strongly suggests that you need 6 clubs for your weak raise when playing short club. One caveat - the chances of holding two clubs is greater in my style since balanced hands with 4 or 5 diamonds also open 1♣ when in range. Anyway, you have been warned.

[campboy]

FWIW I found some figures I calculated some time ago. As Phil says, these are all a priori probabilities and will change significantly as soon as you inspect the faces of your cards.

Strong NT      Weak NT
2     4.0%     2     2.9%
3    15.6%     3    11.3%
4    24.8%     4    19.6%
5    34.3%     5    39.0%
6    17.1%     6    21.9%
7+    4.2%     7+    5.3%

[rhm]

PhilKing, on 2014-July-31, 07:47, said:

I hestitate to mention Bayes', but if we hold 5 clubs and 6-9 points, the chances that opener holds 2 clubs goes way up from the modest headline figure.

The first point is obvious: the presence 5 clubs in our hand reduces the odds that partner has club length. The second is more subtle: if partner has club length, there is a somewhat greater chance that RHO will have a hand that wishes to intervene.

So when you decide to jack it up with a raise to 3♣ on such hands, don't be surprised if partner continually shows with a balanced hand with two clubs. My experience strongly suggests that you need 6 clubs for your weak raise when playing short club. One caveat - the chances of holding two clubs is greater in my style since balanced hands with 4 or 5 diamonds also open 1♣ when in range. Anyway, you have been warned.

These arguments are valid of course, but your caveat is by far the major reason you require six and find dummy frequently with two.
Requiring 1♦ to be unbalanced is a very different animal and not without serious drawbacks. They are also subtle and prone to be overlooked.

Rainer Herrmann

[helene_t]

Zelandakh, on 2014-July-31, 02:38, said:

I await the day when I can bid 1m "naturally" with a void in the suit opened!

For a short while (I think it was just for the duration of the World Championships in Shanghai), a 0+ 1♦ opening was natural for the purpose of the BSC definitions (i.e. the defences against it were restricted).

But really, I think that we shouldn't take the word "natural" too seriously. We can use it but we just have to acknowldge that we are not very specific when doing so.

On-topic: I agree that you should pretend that the 1♣ opening is natural. Try to cater to a 3-card suit as long as there is no suggestion that is is longer, i.e. don't make a non-forcing raise to the 3-level with less than 5-card support. But don't worry about it being a doubleton, and don't worry about club stoppers when considering bidding notrumps.

[Tryggolaf]

Vampyr, on 2014-July-30, 17:52, said:

You need to give your opening 1NT range (and your 2NT range even) before anyone can produce a calculation for you

My 1NT is 15-17 and 2NT is 20-21.

rhm, on 2014-July-31, 03:32, said:

Disregarding the possibility that opener has 2 cards is in my opinion okay, but assuming more than 3 cards in clubs in opener's hand is problematic.
As a rule any direct club raise should show 5+ cards. This is useful information to both opener and responder and helps knowing when to play clubs and how high.
If responder is precisely 3♠=3♥=3♦=4♣ and unsuitable for a notrump bid, the roof won't always fall in if you respond 1♦ to 1♣.
When an opponent overcalls or preempts, responder might have to bid clubs based on only 4 cards if nothing else fits.

Rainer Herrmann

Does the security you receive by increasing the amount of ♣ in the inverted minors direct club raise (i.e. 1♣-2♣) from 4 to 5 outweigh the reduced effictiveness of all the open bidding space you lose with responder having just 4 ♣ and 10+? The way I envisioned it, although I have to admit it hasn't occured in a live game yet, after 1♣-2♣ opener should only embark past 2NT holding 4+ ♣.

With regard to overcalls or preempts, I guess they're a bit tricky after both players of the opener's side know they hold at least half the points in the game but they shouldn't surprise us in the aggressive game of these days. Couldn't you have the (implicit) agreement that after an overcall/preempt, only opener is to bid ♣ since he knows whether or not there is a club fit with partner's 4(+) ♣? Combined with situational awareness: after an overcall/preempt, even responder might be able to figure out opener's minimum ♣ length since opener has to have exactly a 43 in the majors if he is to have precisely 3 ♣. For example: 1♣-1♥-pass-2♥-pass-pass and responder knows there is ♣ fit if he holds 3+ ♥ with the opponents holding 8+ ♥ which makes it impossible for partner to hold 3 ♥ and thus rules out the possibility of opener holding 3 ♣.

campboy, on 2014-July-31, 13:21, said:

FWIW I found some figures I calculated some time ago. As Phil says, these are all a priori probabilities and will change significantly as soon as you inspect the faces of your cards.

Strong NT      Weak NT
2     4.0%     2     2.9%
3    15.6%     3    11.3%
4    24.8%     4    19.6%
5    34.3%     5    39.0%
6    17.1%     6    21.9%
7+    4.2%     7+    5.3%

Inspecting the NT line, opener holds 4+ ♣ 80% of the time. But I guess the inverted minors thingy increases the chance of shorter clubs since responder has clubs and is short in the majors (while opener needs to have some length, 43/44, in the majors in order to have shorter clubs). We might need specific inverted odds.

PhilKing, on 2014-July-31, 07:47, said:

I hestitate to mention Bayes', but if we hold 5 clubs and 6-9 points, the chances that opener holds 2 clubs goes way up from the modest headline figure.

The first point is obvious: the presence 5 clubs in our hand reduces the odds that partner has club length. The second is more subtle: if partner has club length, there is a somewhat greater chance that RHO will have a hand that wishes to intervene.

So when you decide to jack it up with a raise to 3♣ on such hands, don't be surprised if partner continually shows with a balanced hand with two clubs. My experience strongly suggests that you need 6 clubs for your weak raise when playing short club. One caveat - the chances of holding two clubs is greater in my style since balanced hands with 4 or 5 diamonds also open 1♣ when in range. Anyway, you have been warned.

Do you think the apparently high possibility of playing 3♣ in a 5-2 fit would be detrimental to your side in comparison with leaving the space wide open for the opponents to investigate their likely major fit?

[FM75]

You can model your bidding agreement and measure distributions using Dealer or the BBO dealer. Refer to the documentation for setting up your scenarios. If you can't figure out how to do this, perhaps it would be advisable to discard the concept. Mike Lawrence trashed the "short club" opening for about 20+ pages in one of his earlier books for partnership and bidding considerations. If you and your partner can't conjure up counters to his thesis, it probably should not be part of your agreement.


It is pointless to consider distributions of a single opening bid in a vacuum. Your bidding system needs to be complete. The "vague" opening bid in a system needs to have have treatment that allows for rational bidding (unopposed and apposed) for all opening bids including the vague one - e.g. 1 diamond in a strong club system. (Just supplying your 1NT range is not sufficient, but it is pretty critical. By the same token, using a strong club, 1 club normally shows nothing about suit distribution - you could be void in clubs and open 1 club.)

Any measurements that you make must be based on random hands, what would be bid on them, leaving your vague bid as "open this with an opening bid that does not meet the standards for another opening bid". It should also take into account dealer position. Vulnerability also enters the scheme. If opener is not dealer, then 1 or 2 opponents had the chance to open, and your partner may have had a chance to do so.