[shevek]

I'm sure many have worked this out. Please save me the grind ...

This is the (common enough) system
1NT = 14-16, includes ALL 5332 (okay to ignore the 2254 hands for odds)
1D = 4+ unbalanced. Uusually 5+, could be 4+1-4-4. Or is that a 1C opening?

1C = 4+ clubs unbalanced, or 11-13/17-19 balanced, no 5cM, so 3-3-5-2 etc

What are the odds of various expected lengths for the 1C opening?
I'm assuming that 2 or 3 card suits are common enough to make (1C) 2C better as natural, rather than Michaels.
Is that the common view?

Switching sides, how do you defend against this?
Common is double as "I would have doubled a natural 1C or 1D opening"
Or should X & 1D both be artificial, Aspro-style?

Going further, what do advancer's club bids mean? Such as

(1C*) 1H (no) 2C

Is this some sort of cue, usually a decent heart raise?
Or is natural & forcing? If so, any new suit by advancer is presumably forcing.
Does the lack of a clear cuebid make the case for transfer advances?

TIA

[Kungsgeten]

Not sure about the odds, but it will be a two or three card suit a lot of the time. I think its reasonable to play 2C overcall as natural. In that case advancer's 2D should be the cue bid. After a suit overcall you need advancer's 2C as a cuebid (or transfer if you play that).

The most common defense is probably X as take-out of clubs. Another option is X as "I would have opened 1C". A third option is X as both majors. You could also play a 1NT overcall as 4 card major and 5+ minor. Have a look at Woolsey's Grunt defense.

[Kungsgeten]

Yeah and some who play 2C as natural then play a 2D jump overcall as Michaels. I personally think the weak 2D jump overcall is very effective against this type of opening though.

[PrecisionL]

I have a manual input spread sheet that I use to calculate opening bid probabilities. Working on taxes, too busy to do the input work this week.

[Trick13]

Using dealer script below (here):

--------------------------------
N_5M = hearts(north) >= 5 or spades(north) >= 5
N_1NT = hcp(north) >= 14 and hcp(north) <= 16
and (
shape(north, any 4333 + any 4432 + any 5332 - 5xxx - x5xx)
or
(shape(north, 2254 + 2245)
and hcp(north, hearts) >=2 and hcp(north, spades) >= 2)
)
N_1D = hcp(north) >= 12 and hcp(north) <= 21 and (diamonds(north) >=5 or shape(north, any 4441 -4414))
N_1C = hcp(north) >= 12 and hcp(north) <= 21 and not N_5M and not N_1NT and not N_1D

produce 1000000
condition N_1C
action frequency "clubs" (clubs(north), 0, 13)
-----------------------------


gives you this distribution

Number of clubs:

2 = 9.8%
3 = 24.2
4 = 26.7
5 = 25.2
6 = 11.2
7 = 2.5
8 = 0.3

[shevek]

Trick13, on 2017-April-08, 18:42, said:

Using dealer script below (here):

--------------------------------
N_5M = hearts(north) >= 5 or spades(north) >= 5
N_1NT = hcp(north) >= 14 and hcp(north) <= 16
and (
shape(north, any 4333 + any 4432 + any 5332 - 5xxx - x5xx)
or
(shape(north, 2254 + 2245)
and hcp(north, hearts) >=2 and hcp(north, spades) >= 2)
)
N_1D = hcp(north) >= 12 and hcp(north) <= 21 and (diamonds(north) >=5 or shape(north, any 4441 -4414))
N_1C = hcp(north) >= 12 and hcp(north) <= 21 and not N_5M and not N_1NT and not N_1D

produce 1000000
condition N_1C
action frequency "clubs" (clubs(north), 0, 13)
-----------------------------


gives you this distribution

Number of clubs:

2 = 9.8%
3 = 24.2
4 = 26.7
5 = 25.2
6 = 11.2
7 = 2.5
8 = 0.3

Thanks for that. I guess opening most balanced 11-counts woudn't change it much.
Choosing 14-16 for 1NT means opening 11-13 bal and accepting the transfer with tha, rebidding 1NT with 17-19.

[Trick13]

shevek, on 2017-April-08, 20:27, said:

Thanks for that. I guess opening most balanced 11-counts woudn't change it much.
Choosing 14-16 for 1NT means opening 11-13 bal and accepting the transfer with tha, rebidding 1NT with 17-19.

balanced 11 is high freq.

2 = 10.2%
3 = 25.1
4 = 27.5
5 = 24.1
6 = 10.4
7 = 2.3
8 = 0.3

[fromageGB]

Kungsgeten, on 2017-April-07, 06:35, said:

The most common defense is probably X as take-out of clubs. Another option is X as "I would have opened 1C". A third option is X as both majors. You could also play a 1NT overcall as 4 card major and 5+ minor.

We play twalsh in a balanced club / unbalanced diamond method. When they open 1♣ against us, other than an artificial strong club, we play "system on" so that (1♣) 1♦ is unbalanced or 6+, and (1♣) X means "I'm opening 1♣", and then we are playing system on. If responder bids, as responders are wont to do, and this is a natural bid, then advancer bids in exactly our methods as to an overcall of our 1♣ opening. We are happy with this and play (1♣) 1NT as a normal strong NT, because the raptor hands of 4M5m are covered by our minor overcalls.

(We do like raptor over a 1M opening, but over a minor, particularly an unknown minor, it is not so useful.)

It could get quite amusing in twalsh over twalsh sequences like (1♣) X (1red), but then you do need different agreements and here we do play 1NT = 4M5m, as we play X for the other major (that's original!) obviously denying a 5 card minor, and completing their transfer is both minors. All suit bids are natural 5 cards.

This is actually our defence to twalsh in 4th seat when it starts (1♣) p (1red) but here the bids are of course stronger. Same meanings.

So you need to agree what you are doing in second seat over their twalsh opening, what you are doing over a twalsh 1red when your side comes into the bidding in 3rd seat, how you handle opposition bidding when you start 1♣ and they bid in 2nd seat, and how you handle their 4th seat intervention. Could be complex.

[DinDIP]

Trick13, on 2017-April-09, 00:18, said:

balanced 11 is high freq.

2 = 10.2%
3 = 25.1
4 = 27.5
5 = 24.1
6 = 10.4
7 = 2.3
8 = 0.3

Thanks for the frequency data T13. It's similar to my calculations: your script assumes canape openings with 6+C and 5 other hands; if that's not the style then the odds of 6+C go up a tad, and the odds of 2/3/4/5 clubs each goes down by a fraction of that.

Not only is this data useful for potential defenders (a 1C opener is likely to have 4+C so a natural 2C or 3C overcall has limited utility especially if you don't effective alternative ways to show hands with 55M) it's also valuable for the opening side: waiting for 6C to make a weak raise to 3C in competition means responder will be missing out on many opportunities to take away the opponents' bidding space.