[sgarlapati]

are there any convention to overcall 1nt.responces.i mean

[Elianna]

Yes, there are.

But it's not clear what you're asking for: Do you mean:

1. When opponents open 1NT and you're overcalling, or

2. When you open 1NT, and they interfere?

[P_Marlowe]

Hi,

have a look at the following side,
it lists several conventions for overcalling
a 1NT opener.
http://www.blakjak.d...k/def_1nt01.htm

With kind regards
Marlowe

[sgarlapati]

i mean how to respond partners 1nt over call in sayc.ty

[Robert]

Hi everyone

There are many methods to bid over your sides' 1NT opening bid 'when' the other pair bids.

I will be teaching a class on beginning bridge, so I just downloaded the ACBL Standard Yellow Card System(revised Sept., 1988)

"If the opponents double, all conventional responses are "on." For example:
1NT-(double)-2C=Stayman. A 2D bid would be a transfer to hearts.

If the opponents bid over your 1NT opener, Stayman and transfers are "off." Bids are natural except for a cuebid, which can be used with game force strength as a substitute for Stayman.

Regards,
Robert

[helene_t]

In SAYC, you treat the 1NT overcall as a 1NT opening. I think this is playable on the basis of the "no double, no trouble" principle. Yet it is clearly not optimal. First, you don't want to play in their suit (at least not if opener showed five cards) so you should use the transfer to their major for something else. Second, since RHO rates to be weak there's little or no advantage in letting overcaller declare. Third, you will frequently want to play at the two-level in the minor.

A possible treatment:
Below their suit: to play.
Their suit through 2♥: transfer.
2♠: asks for a 4-card in the other major.

Also, in SAYC system is on when they double 1NT. This is reasoble since a double of a 1NT opening could mean a zillion different things and even if you developed optimal defense against each of them you would still be in trouble when the opps give a vague explanation.

But after they double partner's 1NT overcall, system should clearly be off. I think this is so obvious that I would assume it even if we have the general agreement that system is on in competition.

It's nice to agree with partner on a meaning of rdbl. Without special agreement, I would assume it to be a weak two-suiter. But I think the reverse is slightly better:
rdbl: one-suiter.
2x: lowest of two suits