Stephen Tu, on 2019-July-16, 22:29, said:
You seem to have fallen into the common int trap of utilizing blackwood as a slam TRY. Blackwood is supposed to be slam AVOIDANCE; you have decided you have 12 tricks unless off two keycards or one plus the queen. The problem is blackwood doesn't tell you if partner has extras or if a key suit is stopped. Maybe you are only off one ace, but you are off AK of one suit. Or maybe you have enough keycards and not two tricks off top, but run out of tricks.
Good bidders resolve these other issues with cue bidding, if they trot out rkc the 5 level should nearly always be safe barring really bad breaks, there's very rarely advantage from the lower ask. Nobody good I've ever seen use 3nt as ace asking; actually I've never heard of this till now. Far more common, if willing to give up 3nt with established major fit, are either "non-serious" or "serious" 3nt, basically a mark time bid that denies or shows extras, vs cues bypassing 3nt, to help in auctions where no one is limited. If one hand's range is already tightly defined, another useful possibility is a shortness ask. When hearts are trumps it can also be useful to swap meanings of 3s/3nt for structure consistency.
When asking for shortness - is this Mathe bids?
I can see that if your suit is hearts - you could have the 3NT bid as serious or non-serious, and ALSO have the 3s bid as asking for shortness.
If your suit is spades - seems like you have to decide on what 3Nt will mean as you cannot do both.
Am I reading this correctly? I am just reading about serious 3nt and mathe now - so this is new to me. But, I really like the idea of getting this information from partner.