Application of Law 12

There is still some strange wording in Law 12 covering what was previously described as the distinction between "consequent" and "subsequent" damage; "subsequent" damage could have been due to wild or gambling action by the non-offending side, by their serious error, or just "failure to play bridge". However, I think the effects are clear: for the offending side (OS) we adust if they obtain a table result better than they would have without the infraction; but the non-offending side (NOS) do not get an adjustment for damage which is self-inflicted, defined as due to a serious error or wild or gambling action (WoGA).

In practice there are four cases: all damage is self-inflicted, some is self-inflicted, no self-inflicted damage, or no damage at all. There are scores we have to consider

1. the score for the Actual table result (including any serious error or WoGA)
2. the score for the result Before infraction (assigned by Law 12C1c or Law 12C1e)
3. (≥ A) the score for the result that Could have been scored, with the infraction but without serious error (could be weighted?)

The overall damage can be divided as

• Real damage: D_R = B − C
• Self-inflicted damage: D_S = C − A

Starting from C ≥ A there are four cases

• C ≥ A > B: no advantage, no damage, no adjustment;
• C ≥ B ≥ A: all damage self-inflicted, no real damage D_R ≤ 0 (virtual damage), NOS get A, OS get B;
• B > C = A: no self-inflicted damage, D_S = 0, NOS get B, OS get B;
• B > C > A: real damage and some self-inflicted.

In the final case, the OS get B and the NOS get A + B − C. The adjustment for the non-offending side can be seen as either

• actual score + real damage: A + D_R = A + (B − C); or
• adjusted score − self-inflicted damage: B − D_S = B − (C − A) = A + B − C.

Examples

NS bid to 4H and EW "use UI" to compete to 4S, which is doubled. In defending 4SX, NS might revoke (a serious error) and lose a trick they would otherwise score. The result in the other room is 4H=, NS +420. This is the normal result in 4H, so B (the result before the infraction) is 0 IMP. The type of adjustment depends on the table result.

4SX-1 NS +100. Revoke

A = IMP(100-420) = −8 IMP. Without the revoke: 4SX-2 NS +300. C = IMP(300-420) = −3 IMP.

Real damage D_R = 3 IMP, self-inflicted damage D_S = 5 IMP.

Offending side (team of EW) get 0 IMP, non-offending side (team of NS) get 0 + (−8) − (−3) = −5 IMP.

4SX-2 NS +300. Revoke

A = −3 IMP. Without the revoke: 4SX-3 NS +500. C = IMP(500-420) = +2 IMP. No real damage (D_R < 0).

Offending side get 0 IMP, non-offending side get −3 IMP (table result).

4SX-2 NS +300. No revoke

A = C = −3 IMP. No self-inflicted damage (D_S = 0). Both sides get 0 IMP.

4SX-3 NS +500.

A = +2 IMP. No damage. Table result for both sides.

Club TD approach to insufficient bids

Another year, another Club TD course (Book Rulings), and more problems with Law 27. See RMB Bridge Laws: Some Law 27 examples with club TDs

The general instructions to EBU TDs is to take the offender away from the table to establist the "meaning" of the insufficient bid and to establish which bids will not silence partner ("rectification" bids). This is a lot of faff for a (playing) club TD, who does not expect to have to collect this sort of information before making a mechanical ruling, and does not expect to have to talk to players away from the table.

As last year, I used the example of 1NT-(Pass)-1S, where 1S was intended as an opening bid. The offending side's responses to 1NT are: Stayman, Transfers, 2S is something artificial related to the minors, 3suit is natural GF. On the course, we see that there is no correction under Law 27B1a and (with prompting) we need to look at 2H and 3S under Law 27B1b. The insufficient bids shows spades and opening values: does this apply to 2H/3S? 2H does not show opening values, so is not a "rectification bid". 3S does show spades and opening values, so looks like it has a more precise meaning than 1S; but would all hands that bid 3S have opened 1S? Some 3S responses to 1NT might have opened an Acol 2S — but this is probably a negative inference that the "liberal interpretation" encouraged by the WBF LC means we should ignore. So 3S is a "rectification" bid (phew!)

At club level, I think we need to simplify the approach to be taken by TDs. Short of ignoring Law 27B1b, it is difficult to see how any simplification can avoid having to talk to the offender away from the table. Even if the TD is prepared to rule on whether a call is covered by Law 27B1b at the table, the offender will not be prepared to make a "rectification" call without checking first with the TD whether or not his call will silence partner. All I can suggest is that the TD uses the spiel I suggested last year RMB Bridge Laws: Law 27: untested spiel and includes in the second option the calls he considers to be rectification calls. If the offender thinks there are other rectification calls only then will he need to have a discussion with the TD away from the the table.

Revised spiel

To offender: don't say anything about why you made the insufficient bid, it may only make things worse.

To LHO: you will have the option of accepting the insufficient bid but first you should hear what happens if you do not accept.

TD decides whether Law 27b1 applies, and whether there are rectification calls under Law 27B1b; based on the existing auction, the convention card and questions at the table about offending side's agreements.

To offender:

• You have as many as three options: the first two, if applicable, will not silence partner, the third option will. We can discuss these options away from the table.
• Firstly, as the insufficient bid and lowest sufficient bid in the same denomination are not artificial, then you have the option of making that sufficient bid and partner will not be silenced.
  OR ... as the insufficient bid or the lowest sufficient bid in the same denomination is artificial, then you do not have this option.
• Secondly, if there is a sufficient bid, pass, double or redouble which means the same as, or is more precise than, the insufficint bid, then you have option of making any such call and partner will not be silenced.
  These calls are ... OR But there are no such calls.
• Finally, you can make any other sufficient bid or pass and partner must pass for the rest of the auction.

To LHO: Do you wish to accept the insufficient bid? You can ask the opponents about their system, but you are not entitled to ask the intended meaning of the insufficient bid.

(If necessary, talk to the offender away from the table, determining which calls will or will not silence partner.)

Allow offender to call, and announce whether partner is silenced. Wait for the end of the auction and ask to be called back if there is a problem.

No postings in August or September

Blog got mentioned in English Bridge.

Today is the anniversary of the surgery on my foot, see no posting in October. I have still got health problems: most obviously a boot to imobilise my left foot, which I have been wearing for eight months.

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).