BBO Discussion Forums: Acol - BBO Discussion Forums

I learned Acol first. And in international competitions I've played Acol with weak NT, Acol Weak NT and 5cM, Acol 2/1, Acol variable and strong NT...

When do these cease to be Acol - who cares. Acol isnt played at the highest level hasnt been for decades.

When do these cease to be Acol - who cares. Acol isnt played at the highest level hasnt been for decades.

Personally I believe that the arrival of the original Precision system bought a more neater bidding system to prominence, and with that, plus the emergence of other 5M systems, will eventually consign Acol to the scrap bin. RIP, Acol old boy...

does anyone have experience playing acol (4 card major, weak nt) with 2/1 responses being game forcing?
would a system like that qualify as acol?

Just saying that the preemptive effect of 1M is a bit lost if its always a strong hand when just being four. Opening a four card 1M when playing strong 1NT is almost as preemptive as opening a weak NT. The "downside" is then when you open 1m with a weak NT and no major (where a weak NT probably would have been better).

I have never really understood the theory behind Acol with weak NT and four card majors. Sure, I understand that it is a natural system and therefore it makes sense -- I just don't understand the merits. The best thing about it must be the minor suit openings, which shows a real suit and always extra playing strength. The same could be said about the majors, but the downside is that it is harder to tell about your length.

The main benefit (to me) fit four card majors is the preemptive effect of the 1M opening. The opening itself might hinder a lower overcall (or you might open their five card suit). It could also be the case that partner raises and fourth hand is in a tougher spot compared to five card majors. I think a lot of these problems for the opponents disappear if playing a weak NT. Now if opener only has four, he'll have a strong NT. Now the opponents probably don't want to enter the auction anyways. You preempt yourself instead.

So with four card majors I'd recommend not opening 1M with a strong NT. I think weak NT fits better with five card majors. The other four card major style is canapé, where you open 1M with 4M and longer side-suit, or 6+M (and maybe some balanced hands).

4-card majors has the advantage that you don't have to worry about whether you play Walsh or not, since
1m-1red
1NT
denies a 4-card major just by logic, it doesn't require a partnership agreement.

I would agree with this. But you could also say that strong5 has little merit - after all, if you play 5-card majors it is quite easy to play weak NT so why don't people do that? Basically, people just play what they have been taught, which for historical reasons happens to be weak4 in the UK and strong5 in most other places.

4-card majors has the advantage that you don't have to worry about whether you play Walsh or not, since
1m-1red
1NT
denies a 4-card major just by logic, it doesn't require a partnership agreement.

Weak NT has obvious benefits.

So while there is, IMHO, negative synergy between the benefits of 4-card major and those of weak NT, it's not like either has zero benefits in the context of Acol.

Why?

Well, I assume that 4-card majors implies that you always open a 4-card major (if you have one) with 4432 shapes.

There are of course styles such as Dutch Acol and Henderson's book in which you open the minor. I don't understand why anyone would play that, IMHO it combines the disadvantages of 4cM with the disadvantages of 5cM. But to each their own.

The defining feature of Acol: 2/1 responses that are 1 round forces only.
You can play 2/1 responses being game force with 4 card major and weak NT,
but this is certainly not an Acol system.

Well, I assume that 4-card majors implies that you always open a 4-card major (if you have one) with 4432 shapes.

There are of course styles such as Dutch Acol and Henderson's book in which you open the minor. I don't understand why anyone would play that, IMHO it combines the disadvantages of 4cM with the disadvantages of 5cM. But to each their own.

It works fine as long as your minors are basically always 4 card suits. There is a style where you play a 4 card heart and 5 card spade, meaning you only open 1♣ on 3 with 4333 15-19. Constructive bidding is actually easier playing this style, you lose out when they can overcall your 15+ hands.

For what it's worth, Jan Eric Larsson's "Good, Better, Best" contains summaries of numerical investigation of these systems. He compares these claims through extensive simulations, much more in depth than any other bridge simulation I've seen. About a third of the book is devoted to discussing possible flaws and inaccuracies.

His conclusion are that 4cM and 5cM are about equal on balance, but of the 5cM systems the 5533 system is better than 5542 (which itself is a lot better than 5551) and of the 4cM systems the "HCSD" order beats the others, though "HSCD" is not far behind while "CDHS" is noticeably worse. Furthermore, strong notrump is significantly better than a weak notrump in both 4cM and 5cM systems.