the dorbel daily

Friday, 11 January 2013

Without A Net.

Regular readers (who deserve more regular posts, apologies) will know that I am a big fan of the early aggressive double. Although sometimes a mistake, it does open the possibility of a very wrong pass (particularly when it comes with a strong whiff of gammon), it does mean that you can't make another doubling mistake in that game and it does mean that your opponent can make a mistake when she redoubles, or more commonly misses a chance to do so. What should Black do here? It's 3-away, 3-away and White is a GBot on Fibs, Gnu 2-ply in other words. Black is on roll, White is on the bar.

Black leads by 130 pips to 179, he has a much better board and White has to enter before she can do anything. Is this enough for a cube? The first thing to note is that there is no chance of a wrong pass, nor will White make a mistake with the redouble, because she is a gnu. However, Black will win about 57% of the games from here, of which 33 will be match winning gammons. Is that enough for a double? No, cubing now is a big mistake. With four men back, White anchored and some useful blocking points in White's outfield to negotiate, waiting is entirely correct and the cube is a blunder. The problem for Black is that he has very few market losing sequences, His best roll is probably 5-5 (23/8, 20/15) and if White dances after that he will actually be slightly too good to double! The rest of the time he will sometimes have a cube, sometimes not and will usually still get a take.

The other downside to cubing for a human is that Black's play isn't always easy, in fact I managed a blunder after double/take when I rolled 6/5. I played 21/10, but the pipcount tells the story. Because I lead, I need to dismantle my back position and start the journey through White's outfield while she is still dancing. 21/15, 20/15 is easily best, establishing a useful outfield point to act as a safe house for stragglers passing through. This roll (and the correct play) is actually a market loser after a dance, but not by much.
Hanging onto an anchor that has become irrelevant is a very common mistake, certainly one that I make a lot and I think it springs from a conception of the anchor as a safety net. Bg can't always be played like that and this position is one where Black needs to play boldly in order to reach a good doubling position, or if he has given the cube away, go for the win!

So bold cubing good, bold cubing in a difficult position with few market losers against a brilliant opponent, bad. Discriminate!
Until the next time, enjoy the game!


Timothy Chow said...

Good position, Paul. I tend to cube in these sorts of positions, which is why my lost equity from wrong doubles is bigger than my lost equity from missed doubles. Against a human I think it's still worth tossing the cube over because they might pass.

By the way, you probably understand this, but it's worth pointing out to your readers because it's often misunderstood: if there's some exchange after which Blue is too good, it still counts as a market loser as long as Blue's D/T equity is higher than his ND equity after the exchange.

dorbel said...

Entirely agree with that Timothy, thanks.