[Bende]

In a natural system with 5cM and 4c♦, an opening bid of 1♣ can be made on 2 cards with a balanced hand. A similar bid would be 1♦ in a big club system, which could show for example a weak balanced hand (maybe with 1+♦) or a natural diamond suit.

A common (I think) agreement when facing such a bid is that a direct bid in that suit ((1♦*)-2♦) is natural while a later bid in the suit is a cuebid unless the opps have bid a different suit. For example:

(1♦*)-D-(p)-2♦ = art. forcing
(1♦*)-1♥-(1♠)-2♦ = natural

Another agreement that is quite common is that (1♥)-D-(1♠)-2♠ is natural (to protect from a potential psyche).

Now, combining these two agreements, what do you think should be the meaning of

(1♦*)-D-(1♠)-2♦?

Is it natural, since opps have bid a new suit, or is it artificial and forcing, since 2♠ needs to be natural to protect from a psyche?

[helene_t]

The reason for playing a bid in RHO's suit as natural is not primarily because it might be a psyche. It is more because you'd rather play with the 4-card trumps to the right than to the left, so it's more logical to play RHO's suit as natural and LHO's as artificial, assuming you need one cuebid in this position.

If 1♣ can be a doubleton only in the specific 4=4=3=2 case, it is essentially the same as a standard 1♣ opening, and I would defend it the same way. OTOH a Polish 1♣ opening should be considered artificial.

[P_Marlowe]

The main reason that one plays 2S in the seq.
(1D) - Pass - (1S) - 2S
as natural is not to protect against a psych, but
that an artifical meaning of the bid is not needed.

You can bid 2-suiters via X or / and 1NT.
And you can bid 1-suiters in the unbid suits direct,
but you may hold a 6 card suit in one of their suits,
especially if they respond with any 4 card suit.

I may live a sheltered life, but it is rare that I encounter
a psych bid, even watching Vuegraph, psychs are rare,
i.e. I would not argue with psychs.

And to answer your question, it makes certainly sense
to play 2D in your last seq. as natural.

With kind regards
Marlowe

[MFA]

My partnership has quite clear understandings about these sequences.

Our general philosophy is to treat all short minor openings (1♣ on 2, precision 1♦ and polish 1♣) as natural bids.

The reasons for this are:

1) We need cuebids when partner has bid something. Being able to show a good raise cannot be overrated.
2) Simplicity.
3) We allow for natural bids in the enemies' suits in many situations even when they show 4+ cards.
4) Even if their opening might be short, on average they do have some cards there, since they didn't open something else.

So we play:

(1mi) - 2mi Michaels, 5-5 majors

(1x) - pass - (1y) - 2x/2y natural (2x is not natural, if x shows 5+)

(1x) - overcall - (1y):
D takeout of y (takeout of x&y if x shows 3+)
2x cuebid, good raise (also after neg dobl)
2y natural
3x mixed raise

(1x) - D - (1y):
D 4card y & values
2x cuebid, inv+, forcing to suit agreement or 2NT
2y natural NF, 5 cards

(1x) - pass - (1y) - 1z
(pass):
2x natural
2y cuebid (good raise)

Sometimes we have to pass and back in with opener's suit later, but this is typically a small price to pay for having a cuebid available.

EDIT:
Forgot; after (1x) - D - (pass), and (1x) - overcall - (pass), opener's suit is a cuebid.

[ArtK78]

The simplest agreement, and the one that most experts have, is that when the opponents bid two suits naturally (and a 2+ card 1♣ opening is considered natural) a direct bid in EITHER suit is considered natural. Double is for takeout. Some play sandwich NT, so that 1NT would be the unbid suits with less defensive strength, double would be the unbid suits with more defensive strength.

So,

(1♣) - P -(1♠) - 2♣ is natural
(1♣) - P -(1♠) - 2♠ is natural

and so on.

There used to be a lot of discussion in The Bridge World about 2 cuebid situations. At that time, many players played that a bid of either of the opponents' suits was a cue bid, one meaning one thing and the other meaning something else. I have not seen much discussion of that in recent years. I believe that most experts have abandoned the 2 cue bid treatment.