IMP scoring
NS vul
1♣ was announced as "could be short". NS, a first-time partnership, have agreed that 2NT shows the two lower unbid suits.
At her 2nd turn, W asked about the 2NT bid and was told "minors". S had made the assumption that clubs counted as "unbid" for the purposes of Unusual 2NT when opener might not have real clubs.
(Let's not get on a tangent about the new ACBL definition of a possibly short 1♣ as "natural".)
West, being well-fortified in both minors, bid 3NT. During the course of play, I was called to the table. I believe this was after N showed out on the 2nd round of clubs, and it became apparent to all that his 2NT bid had been based on hearts and diamonds. The hand was played out and 3NT was defeated.
West was insistent that she would not have bid 3NT had she known that N had hearts. West had ace-doubleton of hearts and did not feel this was adequate as a stopper. You may or may not agree with this bidding judgment, but knowing this player I am confident that she would not have bid 3NT had she been told that 2NT showed the red suits.
I therefore ruled that W had received MI, and (being in the ACBL) I assigned a score based on likely and at-all-probably results. Absent West's 3NT call, North would bid 3♦ (or 3♥) and this would go one off, undoubled.
Lingering questions:
(1) Is North allowed to run from 3♣ if West passes? It is technically a cuebid, but it's also what South would bid with 7 clubs and out.
(2) In terms of the assessment of damage, does it matter that East did not really have his double? After all, the double occurred prior to the MI.
(3) Again thinking about damage, does West's play of 3NT come into consideration? She misplayed the hand badly, making only four tricks when six would be more normal and seven are available double-dummy. Should a score adjustment address "that part of the damage which was self-inflicted", and if so, how would this be reflected in the adjusted score.?
Thoughts appreciated. Thanks.