Posted 2019-November-20, 10:20
The problem is that it is at least very common, if not standard, to play that a 2/1 response here is NOT forcing: I think this stems from the historical standard treatment that one always redoubles with 10+
Now, after 1x (x), a bid of a suit at the one-level, so 1C (x) 1S, has for many years now been treated, by all experienced players, as saying nothing about hcp...one bids it with 6 points and 4 spades as well as with 13 points and 6 spades. But as far as I am aware, that practice has not extended, at least not to the point of becoming standard, to a 2-level response.
The question is one of frequency. When partner has an opening hand, and so does RHO, are we likely to have 10+ and a 5+ suit or is it more useful to be able to bid, say, 2D here with xx xx KQ109xx Jxx? To me, the advantage of bidding 2D is clear. We stop 4th seat from being able to bid 1S (or 2C), and we make the range of his 2S bid (which would be a jump had we passed) ambiguous. We also get the lead we probably want, and we may find a fit allowing us to compete.
As it happens, many experienced pairs avoid this issue altogether. In my partnerships we play that 2C would be a transfer to diamonds: opener assumes, for his next action, that I have the 'weak two' type of hand, but of course I can bid again to show that I have extras...including changes of suit, cue-bids (if the opps speak) and so on.
So the answer to the OP is 'it depends'. If 2D is weak, as I would assume it to be absent discussion (so long as I thought partner knew something about how bidding has developed over the years), I would be forced to redouble. Do I like that? No. Which is of course why transfer advances over takeout doubles were invented. If I thought that partner believed that 2D shows a good hand, I'd bid 2D, wtp?
'one of the great markers of the advance of human kindness is the howls you will hear from the Men of God' Johann Hari
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Given TramTicket's methods, 2♦ seems preferable to redouble as it makes it harder for opponents to find a ♠ fit.
TramTicket Q2 'More generally, when would you redouble to show values? And when do you bid your suits constructively?'
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Redouble with an interest in penalties. Ideally, shortage in partners suit and values in each of the other suits.
TramTicket Q3 'As a follow-up question, if you did redouble as per this comment what do you do when the bidding continues with the inevitable 1♠ response and a penalty double from partner'
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Partner's double is for penalties, so pass provides a reasonable prospect of a good score.