Application of Law 12C1(b) revisited

I have been called on a number of times recently to advise on the application of Law 12C1(b) — adjustment for non-offending side following self-inflicted damage, due to a SEWoG. I have written a spreadsheet to display the calculations (feedback welcome). As a consequence of writing the software, I now better understand the calculations and I have rewritten my article, which subsequently appeared in the EBU White Book.

Application of Law 12C1(b)

There are scores (for the non-offending side) 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)
3. the score for the result that Could have been scored, with the infraction but without serious error

The corresponding scores for the offending side are A', B', C'; at IMPs A' = −A, etc.; at match points A + A' = top, etc.

The overall damage D (= B − A) can be divided as

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

There are four cases: all damage is self-inflicted, some is self-inflicted, no self-inflicted damage, or no damage at all.

• B ≤ A: no advantage, no damage, no adjustment;
• A < B ≤ C: all damage self-inflicted, no real damage D_R ≤ 0, NOS get A, OS get B';
• C ≤ A < B: no self-inflicted damage, D_S ≤ 0, balancing adjustment, NOS get B, OS get B';
• A < C < B: real damage and some self-inflicted.

In the final case, the OS get B' and the NOS get A + B − C = adjusted score − self-inflicted damage.

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 NS +50. The expected result in 4H is making, so B (the result before the infraction) is +9 IMP for the non-offending side.

4SX-1 NS +100. Revoke

A = IMP(100-50) = +2 IMP. Without the revoke: 4SX-2 NS +300. C = IMP(300-50) = +6 IMP.

Damage D = 7 IMP; real damage D_R = 3 IMP, self-inflicted damage D_S = 4 IMP.

Offending side (team of EW) get −9 IMP, non-offending side (team of NS) get 2 + 9 − 6 = +5 IMP.

4SX-2 NS +300. Revoke

A = +6 IMP. Without the revoke: 4SX-3 NS +500. C = IMP(500-50) = +10 IMP. No real damage (D_R < 0).

Offending side get −9 IMP, non-offending side get +6 IMP (table result).

4SX-2 NS +300. No revoke

A = C = +6 IMP. No self-inflicted damage (D_S = 0). Both sides get ±9 IMP.

4SX-3 NS +500.

A = +10 IMP. No damage. Table result for both sides.