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BGonline.org Forums
What do you do here?
Posted By: Stick In Response To: What do you do here? (tem_sat)
Date: Monday, 11 October 2010, at 10:13 p.m.
This problem is a prime example of why everyone (not only strong players) should be hugely in favor of clocks. There's a lot I would figure out exactly if I had the time here whereas if I was on a clock I'd take more of a flippant approach and go with my gut feeling of slotting the ace point and playing 14/10.
As the trailer I would like to know where my opponent's raw take point is because in theory I could close him out now and start thinking about a cube. He's ahead in the match and more specifically two away from winning. He also can't lose a gammon, this usually means his raw take point is lowered from money but let's double check any way since you didn't make me play with a clock.
- Double/Pass gives -2 -4 for 67% ME
- Double/Take lose gives -2 -3 for 60% ME
- Double/Take win gives you the match, 100% ME
You'd be risking 7% to gain 33%. (risk/(risk+gain)) = (7/(7+33) or 7/40 = 17.5% as my opponent's raw take point.
If you happened to pay too much attention to a recent post of mine you'd know that 10 checkers borne off and the perfect spare distribution you would be 32%. This position is slightly different in that you don't yet have the perfect spare distribution but if you make the ace point now you do have the start of a good distribution so that portion lost is negligible.
The most important difference is that in my example your opponent's checkers were all on his ace and deuce point whereas here they're on his ace and three points. This matters in a big way as if you're forced to bear off aggressively you could be hit and he could later break his board and you could shoot at other blots. It is also minorly important in the most obvious way, his bearoff is worse. I would guess this change adds 2-3% game winning chances to our reference position of 32% so closing the ace point right now yields between 34-35%.
Now, on to the other plays. The first thing you have to remind yourself is that by slotting the ace point now you are still risking the freak occasions where you lose a gammon. Making the ace point you're off the gammon 100% so you need to see the trade off between extra wins by slotting the ace point compared to the gammons lost. You will also need to know how valuable a gammon is for your opponent on a centered 2 cube. Again, common sense should tell you since he's 2 away from winning a centered cube gammon is much more valuable than normal.
While most gammon values I either have memorized or just a good basic idea where I stand, again, you didn't put me on a clock so I'm going to figure out my opponent's exact gammon value. The formula for this is simple, gain/risk.
- Wining a single game puts him at -1 -5 C or 84%
- Winning a gammon gives him the match or 100%
- Losing a single game puts him at -2 -4 or 67%
Therefore we will be gaining 16% (100-84) while risking 17% (84-67). 16/17 gives me over .9 as the gammon value, not far off from pure gammon go.
At this point I would deem 14/10 3/1 as a better play than 11/7 because it's clear to me that slotting the bar loses more gammons. You don't need an extra cover for the ace point, you're not even sure you're trying to cover it. Putting that blot there allows the immediate 61 to be more painful than you can stand and the other aces your opponent may get to shoot at that blot on the next turn depending on the sequence. 11/7 is too rich imo, so I'm down to the other slot play and making the ace point.
At dmp I'm sure I'd slot and go for the extra checker meaning that play must win more single games, again, is it enough to make up for the freak gammons I lose? If you haven't looked at these types of positions before I think you would underestimate the gammons lost by slotting. The reason you lose 'so many' is that often when you are hit, you again hit loose in these variations and keep trying for the second checker so when things go sour you may have several blots hit or several men in the outfield. I would take a wag of 5% gammons lost from here by the slotting play.
Another thing you should think ahead to is when should you be recubing? If you make the slotting play do you recube when you have a shot at another checker? Of course not, not with your opponent's tp being so low. How about if you hit the second checker and your opponent fans? This is probably where I think a recube is justified.
How about when to recube if you merely close the checker out? The general rule for money is 'when you get to within' 5 checkers off of your opponent'. There will be lots of variations and that loose rule applies only to your opponent still being on the bar. I would imagine here you'd need to wait until you had 4 less borne off than your opponent.
I'm out of time, someone else can finish this analysis if anyone made it this far to begin with.
Stick
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