So I played this safely with 6/1, and GNUBG reported it as a -0.047 mistake in favor of 8/5 7/5.


Is this a case where the need to plug that hole outweighs the danger of leaving a double-shot? Because that blot in his home board and my 30-pip lead seems like thin consolation for the likely hit.

Here's what I think is going on:

You are focusing on the short-term risk of getting hit, but you have a long-term problem in this position. Your position consists of many points with only 2 checkers plus a single stack on the 6 point. This makes it difficult to find moves that avoid leaving blots, because if you don't play from the stack, you have to move both checkers from a point to avoid leaving a blot.

Even if you play safe now, it is likely you will have to leave a blot in the upcoming rolls. Thus, it is better to pay now, while there is a blot in the opponent's home board. If not hit, this frees up the checkers on the 8 and 7 points for some more moves. If you wait, you may be forced to leave a blot at a time when the opponent has a 4 point board. It will be much worse. You can see this if you adjust the position by moving one of the opposing checkers from the midpoint to cover the blot in the home board. Now 8/5 7/5 is wrong, and you have to play the safe 6/1.

Time to upgrade your software. An XG rollout makes 6/1 the slightly better play. XG isn't free but it is the best software out there.

When I rolled it out in XG, it still likes 8/5 7/5 slightly better. Probably I'm using slightly different rollout settings.

For the OP: the important point here is not the differences in software or settings, but the fact that the plays are clearly pretty close so it is important to understand why 6/1 is not obviously a lot better.

Agreed. The plays are close, and grape5's explanation was on the money.

In a sense this is a 'pay now or pay later' problem. By making the 5-point you are taking a risk now, when White's position isn't strong, to get a much better home board. Playing 6/1 is safe but leaves you with a more difficult position to play. At the same time White's position will get steadily stronger as he moves his spares on the midpoint to fill in his board. You will often find yourself having to leave blots later when getting hit will cost you the game instead of just a few pips in the race.

I think you guys are right on point - a pay now or pay later scenario where paying now enjoys the benefits of an easier re-entry (and a possible return shot) and strengthening my home board. I've been guilty before of downplaying the risk of holes in front an opposing anchor when trying to bear off, hence my misinterpretation of GNUBGs recommendation. Thanks for the clarity.