The LAW

We all now the LAW, don't we? In this competitive bidding, we see 10 cards in spades. So, we bid 4♠. The hand came up in the free weekly tournament, and I got a 39% result.

The reason for this poor result is not that the LAW does not work. In fact, it works amazingly well. Opponents can indeed make 5♥. for 650, while I went down three times for 500. But East's hand is not good enough and he can be almost certain that we fail in 4♠. Only West could have had the idea to go to the 5-level. But it depends on finding the ♥K and not losing two diamond tricks. It's not a good bet. Not even 4♥ is bullet proof.

What actually happened, however, was that the majority of players did what I did. But two other players went down only 2, because Ben ducked the small diamond played towards the king, scoring 90%. Then there were two more players who opened 3♠ scoring close to 100%. 

That raised my interest in this hand. Should we open such hands preemptively? To test this, I shuffled the other three hands many times and computed the number of tricks I could achieve in spades. My Java program "Bridge Replay" can do that (see on SourceForge). It turns out that making 4♠ will be possible about half the time.

That does not mean, of course, that we should bid on average outcome with random cards. After all, opening 1♠ has the advantage that we can explore the chances precisely! The decision is rather if it is more important to block the opponents from making a game, or to not miss a game on our side. 

To decide that, we can use the same tool and see that opponents have a very poor chance of reaching a game, given the South cards and random cards in the other hand. So, 1♠ should be preferred over the preemptive opening.

Can this all be done at the table? Well, only world class expert can answer this.