Can 4NT be "incontrovertibly not artificial" ?

Another more interesting insufficient bid from Devon!

W	N	E	S
1S	2H	X	3H
X	4H	5D	P
4NT
5NT

North pointed out that 4NT was insufficient, and West said something like "oh dear, well I can make it good" and bid 5NT, someone suggested it wasn't as simple as that and the TD was called. I (the TD) decided that I should talk to West away from the table, and she told me that she intended 4NT as natural (to play). I decided that I would err on the side of allowing the auction to continue, prepared to fall back on Law 27D if the other side were damaged. So I ruled that if North did not accept 4NT, the correction to 5NT must stand (Law 27C) but would not silence partner. I thought I was ruling under Law 27B1(a) that 4NT was "incontrovertibly not artificial" but perhaps I was ruling under Law 27B1(b) that 5NT had "the same meaning as" 4NT.

5NT ended the auction and was destined to go off. I told the table to call me back and left the table.

But it's never that simple.

I returned to the table to point out that if I had ruled that 4NT or 5NT was artificial, then East would be silenced anyway. Meanwhile, West had explained that there had been a misexplanation. The first double had been explained as take-out, showing the minors, and the second double had been explained as take-out, equal length in the minors; but West had intended the second double as penalties. The misexplanation did not appear to damage North-South but I guess there was heaps of unauthorised information.

I repeated my instruction to be called back but I heard no more: I guess 5NT went off.

Insufficient bids in Torquay

Good

A few natural insufficient bids passed off almost without mention of the new law. At least twice, a player had make an insufficient bid of a new suit in a competitive auction, I found myself saying

If you bid three hearts (or any other call that shows hearts) then partner can bid again, otherwise ...

Bad

There was a more complicated example:

W	N	E	S
1NT (12-14)	2C (nat)	2S *	3C
2NT

Nobody had asked about 2S, so I did: "balanced invitational or slam try". So if South had passed 2NT shows a minimum 1NT, I asked: "Yes". I ruled that 2NT was not artificial and that Pass would show the same as 2NT, so West could bid 3NT or Pass without silencing partner.

Ugly

I made the mistake (!) of hanging around for the rest of the auction.

W	N	E	S
1NT (12-14)	2C (nat)	2S *	3C
2NT/P	P	3S	End

So I intervened and reminded EW of their obligations, both thought that the explanation of 2S was (still) correct. Their card showed "Modified Lebensohl" (but this meant system on, with stolen bid doubles). East said he had made a mistake, and North asked if West was allowed to know that East had made a mistake. I answered "No" and asked NS to call me back; but the hand records showed 3S was three off, and I was not called back.

No surprises that East had a weak hand with five spades, it was more of a surprise that North had four clubs and five diamonds.

VBA code to calculate par for zero-sum butler

Function par(ByVal scores As Range, Optional ByVal delta As Integer = 10)
    ' scores is the range of cells containing the scores
    ' delta  is the smallest difference between scores
    On Error GoTo par_error
        If scores.Count = 1 Then    ' dispose of trivial case
            par = scores.Value
            Exit Function
        End If
        
        Dim data
        data = scores   ' read range into array, for efficiency
        Debug.Assert IsArray(data)
        
        Dim par1 As Integer, par2 As Integer
        Dim sum1 As Integer, sum2 As Integer
        ' set initial values to bracket the par value
        par2 = 8000
        par1 = -par2
        sum2 = scores.Count
        sum1 = -sum2
        While par2 - par1 > delta
            par = delta * Fix((par1 + par2) / (2 * delta))
            
            Dim sum As Integer, i As Integer, j As Integer
            sum = 0
            ' calculate the net sum of imp scores against par
            ' imp_() is a function to calculate the IMP scale
            For i = LBound(data, 1) To UBound(data, 1)
                For j = LBound(data, 2) To UBound(data, 2)
                    sum = sum + imp_(par - data(i, j))
                Next j
            Next i
            If sum = 0 Then Exit Function
            ' if we haven't found par, adjust the bracket
            If sum < 0 Then
                par1 = par
                sum1 = sum
            Else
                par2 = par
                sum2 = sum
            End If
            ' check we haven't lost the plot!
            Debug.Assert par1 < par2 And sum1 < 0 And 0 < sum2
        Wend
        ' if we can't find a par value giving sum = 0
        ' take the par will the smallest sum ...
        If (-sum1) < sum2 Then
            par = par1
        ElseIf sum2 < (-sum1) Then
            par = par2
        ' ... splitting ties choosing par nearer zero
        ElseIf par2 > 0 Then
            par = par1
        Else
            par = par2
        End If
    Exit Function
par_error:
    MsgBox "Error in par: " & Err.Description
    par = CVErr(xlErrValue)
End Function

Butler scoring and other abuses of the IMP scale

I posted some random thoughts on butler scoring on a thread IBLF and earlier I promised something here on butlering so here it is.

IMP scale

I think that when you compare a pairs score with par, the difference should be doubled before converting to IMPs. The par score should not be thought of as the result in the other room but as the average of the two results at the two tables of a match. To recover the "teams result", the diffence between one real score and the average/par score needs to be multiplied by two before converting to IMPs. If you like, the IMP score can then be divided by two to represent the actual contribution of each of the pairs in a team. (Obviously this won't affect the relative scores of different pairs.)

Calculating par

Someone else on IBLF said it was obvious that the scores for all the NS pairs should sum to zero, since this determines the par score it should be used to calculate par. Other ways of calculating par approximate to this but you might was well use this desired property as the definition. Implementation is easy, some sort of binary chop will work. You need some rule for deciding what to do when there is no zero-sum par. I suggest minimizing the absolute value of the sum of the NS scores, splitting any tie by picking closest par to zero.

Barking alternative to butler for teams of eight

Another abuse of the IMP scale is to score teams-of-eight by aggregating the four scores and converting to IMPs. This is done in the Eastern Counties League and the Berks and Bucks league. You can use forms of butlering to compare the performance of the pairs in such teams-of-eight matches, or you could use cross IMPs. I think the right form of cross IMPs is

IMP(A+B+C+D) + IMP(A-B+C-D) + IMP(A-B-C+D)

to calculate the score for pair A, with pair B sat the same way, and other pairs of the team (C, D) sat the other way. This formula can be extended if there are multiple matches (in different divisions) played at the same time with the same boards. A pair is compared with all other pairs sat the same way against all possible pairs of pairs sat the other way; with all scores from four different tables. If there are two matches (8 tables) then the three terms above become 105, and if there are three matches (12 tables) there are 495 terms. When I implemented this, I described the scoring option as "barking" (a pun on my name and anticipation of other people's reaction).

Self promotion

Effective today, I have been promoted to EBU National Tournament Director — to join an illustrious list. Thank you to the various colleagues who have taught and encouraged me in my rise through the ranks, starting from the county director's course in 1990.

Inadvertent designation is an offense?

I had a routine application of Law 45C4(b) ("... may change an unintended designation ... without pause for thought"), except that the next player had managed to play a card.

Declarer called for ♦10 from dummy and then said he meant ♣10, he said he had been looking at the dummy's clubs at the time, but RHO had followed to ♦10 with ♦7. I was content that the designation had been inadvertent and ruled that the ♦7 can be withdrawn (and must be, if RHO has a club) and that ♦7 was authorised to the LHO and unauthorised to declarer, and to call me back if the defence felt damaged.

Then I checked this in the law book, which said what I thought it said, but Law 45C4(b) ends with "see Laws 47D and 16D1". Law 16D says that withdrawn actions are authorised to non-offenders (16D1) and unauthorised to offenders (16D2). Elsewhere in the laws, there are references to Law 16D or specifically to Law 16D2, but this is the only reference to Law 16D1. I don't understand why the laws have gone out of their way to specify just Law 16D1 here.

• Do the laws think there is no offending side in Law 45C4(b)?
• Specifically, was information arising from ♦7 authorised to declarer?

Alerting doubles in the EBU

The EBU has decided to keep its current regulations for alerting of doubles. There are a number of issues with the current regulations which players and TDs have to be aware of.

Undiscussed doubles

A Brighton in 2007, a player doubled the final contract after the opponents had bid three suit and partner had overcalled in the fourth. Partner decided the double was penalties, based on general bridge knowledge rather than any partnership agreement, and did not alert. The opponents felt misinformed but got no satisfaction from the TD, the AC, or the commentators in the EBU Appeals booklet.

EBU regulations say that this double was alertable unless it was takeout but elsewhere that inference from general bridge knowledge are not alertable. However, general bridge knowledge often says that doubles are penalties, either through bridge logic or as a default. Does the regulation about general bridge knowledge apply to doubles? If so, should the regulations on doubles indicate that the meaning of an unalerted double is either "takeout" or "no partnership agreement".

Lightner doubles

Doubles of the final suit (slam) contract, which ask for a lead of a suit (not trumps) are alertable. This may not have been the intention but it is agreed that this is what the regulations require. But sometimes it is unclear if a double should be Lightner, or there is no partnership agreement only general bridge knowledge. This leads to the same problem as "Undiscussed doubles".

I'll post this now, but there will be a follow-up on doubles of pass-or-correct and preference bids, and 1m-(1H)-X. I also intend to blog on the subject of butlering: my "barking method" for calculating par and a modified scale (half the imps of twice the difference scale).