[jillybean]

Can someone help me regarding hand shape of the 1nt(forcing) hand after partner opens 1M ?

I think I need to know hands that do not have 3+ card support for partners opening major and not 4♠

Thanks

[dave251164]

AI Overview
The 1NT forcing response by the responder typically shows an unbalanced hand with (6-12) HCP that lacks 3-card support for the opener's major.
Because it serves as a "dustbin" bid for hands that cannot make another natural response at the 2-level, it can be of any shape (balanced, semi-balanced, or completely distributional).
Typical Shape Characteristics No 3-card support: Responder does not have enough length in the opened major to raise partner.No 4-card major unbid: If partner opened 1heart, responder does not hold a 4-card spade suit (otherwise, they would bid 1\spade).
Distributionally awkward: The hand shape makes bidding a new suit impossible without jumping, or the hand is not strong enough for a standard game-forcing 2/1 bid (e.g., 10-11 invitational points.

[apollo1201]

To further elaborate on Dave s nice summary, these hands bid 1NT over 1H.

Qxx
Ax
Jxxx
xxxx

Jxx
x
QJxxxx
Axx

And same here over 1S.

xx
Qxxxx
Axx
Kxx

-
Kxxx
xxxx
AJxxx

They all met the criteria re no support, less than 4S over 1H, and no strung enough to bid 2 (or 3) something of a cheaper suit. Yet you have some bal, some semi-bal and some very distributional.

[pescetom]

apollo1201, on 2026-May-20, 14:31, said:

And same here over 1S.

-
Kxxx
xxxx
AJxxx

First board of a national tournament after a strong espresso, with something very similar I automatically responded Double.
Assistant Director that I called to table was at a loss what to do

[jillybean]

I'm asking the wrong question, I want to know the likelihood of the distributions, specifically, having 2 clubs

[thepossum]

pescetom, on 2026-May-20, 15:12, said:

First board of a national tournament after a strong espresso, with something very similar I automatically responded Double.
Assistant Director that I called to table was at a loss what to do

[thepossum]

jillybean, on 2026-May-20, 16:16, said:

I'm asking the wrong question, I want to know the likelihood of the distributions, specifically, having 2 clubs

Could take some time unless someone has already written the script


***********************************
Sorry for doing this but I am quite impressed so far. The script is in development but took Chat GPT a few seconds to write after I tried an initial specification. It seems to roughly work in dealer but obviously not perfect. Still in development. It may help someone. Still working on it then may try some stats. Obviously needs some tweaks for different types of West, and different seat positions and vulnerability and pre-empts and the like, doubles and so on. But still under development and initial tests 9 out of 10 produced the correct auction. And I need to check my system notes for 1NT over an overcall. Do you want to cover opening in different seat positions too. Maybe I will get back to you in a week unless someone like David Kok already has one

generate 1000000
produce 100

condition
(

/* =========================================
SOUTH OPENS 1 HEART
WEST PASSES
NORTH RESPONDS 1NT FORCING
========================================= */

(
hearts(south) >= 5
and hcp(south) >= 11
and hcp(south) <= 21

/* West does NOT act */

and not (

/* 1S overcall */
(hcp(west) >= 8 and spades(west) >= 5)

/* 1NT overcall */
or (hcp(west) >= 15)

/* 2-level natural overcalls */
or (hcp(west) >= 10 and clubs(west) >= 5)
or (hcp(west) >= 10 and diamonds(west) >= 5)
or (hcp(west) >= 10 and hearts(west) >= 5)

/* weak/preemptive actions */
or (hcp(west) <= 9 and clubs(west) >= 6)
or (hcp(west) <= 9 and diamonds(west) >= 6)
or (hcp(west) <= 9 and hearts(west) >= 6)
or (hcp(west) <= 9 and spades(west) >= 6)
)

/* North bids forcing 1NT */

and hcp(north) >= 6
and hcp(north) <= 12

/* no heart raise */
and hearts(north) <= 2

/* no 1S response */
and spades(north) <= 3
)

or

/* =========================================
SOUTH OPENS 1 SPADE
WEST PASSES
NORTH RESPONDS 1NT FORCING
========================================= */

(
spades(south) >= 5
and hcp(south) >= 11
and hcp(south) <= 21

/* West does NOT act */

and not (

/* 1NT overcall */
(hcp(west) >= 15)

/* 2-level natural overcalls */
or (hcp(west) >= 10 and clubs(west) >= 5)
or (hcp(west) >= 10 and diamonds(west) >= 5)
or (hcp(west) >= 10 and hearts(west) >= 5)
or (hcp(west) >= 10 and spades(west) >= 5)

/* weak/preemptive actions */
or (hcp(west) <= 9 and clubs(west) >= 6)
or (hcp(west) <= 9 and diamonds(west) >= 6)
or (hcp(west) <= 9 and hearts(west) >= 6)
or (hcp(west) <= 9 and spades(west) >= 6)
)

/* North bids forcing 1NT */

and hcp(north) >= 6
and hcp(north) <= 12

/* no spade raise */
and spades(north) <= 2
)
)

action printall


*********************************
END script in development
*******************************

I guess there is a simpler estimate that pay not happen at a table

Apparently someone called Ed Judy did some sims of forcing and non forcing 1NT a while back
https://bridgewinner...mi-forcing-1nt/
May be relevant. Not sure if his script is up. It could provide the basis of distribution calculations

I am sure somebody knows or can guess the answer


EDIT
If you want a phenomenally crude estimate where South deals and opens 1 spade, West is totally igorned and North has only 2 or fewer spades and between 6 and 12 points I can give you aa rough initial estimate of 0.33 percent have 2 clubs. very crude way of doing it. If you start introducing constraints on West the probability drops quickly. And then multiply it up by all the differnt seating configurations

EDIT 2 as I said oputting cnditions on West reduces the propability significntly. I now have probability of 2 clubs approx 0.03 percent

EDIt 3 as everyone will know during development nothing is reliable and has infinte disclaimers


0 clubs - essentially zero
1 club - approx 0.7 percent
2 clubs -approx 5 percent - has indeed grown with a proper sim
3 clubs approx 17 percent
4 clubs approx 30 percent
5 clubs approx 28 percent
6 or more clkubs - approx 20 percent

And I doubt that adds up to 100

I supsect something to do with conditional and aboisluyte probability, and we are still assuming South is the dealer

[mw64ahw]

You'll need to be more specific in terms of whether you play WJS/IJS etc.

[mikeh]

jillybean, on 2026-May-20, 10:23, said:

Can someone help me regarding hand shape of the 1nt(forcing) hand after partner opens 1M ?

I think I need to know hands that do not have 3+ card support for partners opening major and not 4♠

Thanks

It’s standard in NA for a 1N, forcing, response to contain 3 spades on some hands.

If one plays constructive or semi constructive single raises, hands too weak for 2M are put into 1N. And ‘everyone’ includes 3 card limit raises in 1N. Indeed, the advocates of 1N SF or NF have to engage in bidding contortions to cope with these hand types.

[jillybean]

Good point.
I am trying to determine what is the most likely minor holding of the 1nt bidder after 1M 1nt

[mikeh]

jillybean, on 2026-May-21, 09:25, said:

Good point.
I am trying to determine what is the most likely minor holding of the 1nt bidder after 1M 1nt

The most likely, by far, is 3 clubs. Second probably 4 clubs, third 2 and fourth 5.

[barmar]

The simple way to understand the 1NT response is that it's the catch-all used for hands that don't have any other bid. So rather than thinking about what it shows, think about what it denies.

So you should have enough points to bid, but not enough to make a 2/1 bid. So at least 6 HCP, and less than shapely 12 points (if you're playing 2/1 Game Forcing) or 10 points (for Standard American).

You don't have at least 3-card support for opener's suit.

If partner opened 1♥ you don't have 4+ spades, since you could bid 1♠ instead.

Everything else in the 6-10/12 point range bids 1NT. Your second call will clarify the nature of your hand.

You can add on some specialized agreements that are exceptions to this. For instance, in many of my partnerships we play 1M-3NT shows 4333 shape and 13-15 HCP; but in one partnership where we have a special meaning for that 3NT bid, we use 1M-1NT-2x-3NT to show that hand.

[mikeh]

barmar, on 2026-May-21, 10:44, said:

The simple way to understand the 1NT response is that it's the catch-all used for hands that don't have any other bid. So rather than thinking about what it shows, think about what it denies.



You don't have at least 3-card support for opener's suit.

You’re the second poster to assert this and that assertion is contrary to every text I’ve read on the forcing notrump and to 40+ years of playing 2/1 gf with and against many WC experts.