Bridge Software to Analize Situations PART 2

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After a 1NT opening bid: Must you play four of a major every time we were known to have fit?

By David Stern
On 9 May, 2013 At 14:24

Category : Advanced @en, Advanced 2

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Source: 4th EUROPEAN OPEN BRIDGE CHAMPIONSHIPS Sanremo, Italia

PART 1 

I recall some years ago having discussions with Tim Seres about an auction where opener opens 1NT, responder transfers and then bids 3NT offering the opener the option of 3NT, of four of his major.

A further discussion involved whether to play four of a major every time we were known to have a 4-4 major fit. On this theme Ron Klinger and I have been engaged in a similar dialogue for somemonths now.

In these situations I like to refer back to my random hand generator and Deep Finesse to provide me with some clues, which I would like to share with you. I ran 5000 hands, which is a sizeable sample, but one should bear in mind that the analysis assumes perfect defence and perfect declarer play and some may argue about the ability to defend better against no trumps than suit contracts.

North 15-17 1NT opening with 4-(3-3-3) 4 makes 84% of the time

South Game Values with 4-(4-3-2) 3NT makes 87% of the time

Note: where bridge writers write 4-(3-3-3) it means exactly four and the other cards in any combination of the cards in bracket.

So 4-(4-3-2) means 4 and the remaining suits in any form of 4-3-2.

North 15-17 1NT opening with 3-(4-3-3) 4 makes 61% of the time
South Game Values with 5-(3-3-2) 3NT makes 75% of the time

So going back to the opening discussion, this analysis suggests that one should not convert 3NT to four of a major when partner transfers and then offers a choice of contracts and you hold a 4-3-3-3 with three card support for partner.

Moving to perhaps the more obvious analytical conclusions:

North 15-17 1NT opening with 4-(4-3-2) 4 makes 89% of the time
South Game Values with 4-(4-3-2) 3NT makes 82% of the time

North 15-17 1NT opening with 3-(5-3-2) 4 makes 82% of the time
South Game Values with 5-(3-3-2) 3NT makes 75% of the time

So the summary is that whenever there is a possibility of a doubleton opposite a doubleton, four of the major is a clear winner but very flat opposite an invite suggests a pass of 3NT to be best. I guess that I could analyse the holding in the doubletons to make the analysis more meaningful but I’ll leave that one for another day.

Esta entrada también está disponible en: Spanish

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