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one of my big blunders this weekend
Posted By: Matt CohnGeier
Date: Thursday, 29 May 2014, at 3:42 p.m.
In Response To: one of my big blunders this weekend (Petko)
It would be interesting to hear MCG's side of the story. I would speculate that his immediate gut reaction was to drop, and when his calculations seemed to indicate otherwise, he felt the need to doublecheck and triplecheck.
My immediate gut reaction was that I actually had no idea what was going on and didn't want to commit to a decision too early. If I had to guess in a few seconds I would probably have said double/take. What I did see was 1) almost all of Petko's wins are gammons, 2) I win a lot of games, and 3) I will ship an 8 cube quickly at this score, so this is very likely to be an 8 point game. It is also very likely that the decision is not a close one. Finally it is a position where you can calculate what is going on (rather than apply judgment, for the most part) so it is reasonable to spend some time working through the math here.
My guess is he spent the time calculating the TP and the GP.
Noactually I had no idea what the TP and GP are and still don't. I assume they're more or less normalish. I would be somewhat shocked if they were not at 00/9.
Then going over all numbers and checking how his replies would play. Then estimating how many G losses, and finally making a decision. Perhaps he had to redo some of the counting to make sure he had it right from the start. Perhaps he realized it was a key moment so it was OK to spend some time on the decision.
Yes, this is pretty much what happened. My thought process went like this:
4 numbers are gin: 65, 66, 55. I get gammoned very often in those games. Not 100% of the time, of course, but pretty damn often. I need some 63 pips to get off the gammon, plus some wastage, and he will probably have 7 or 8 rolls with all sets working for him. That means I am a big underdog to save gammon without a hit.
If I hit, I don't always win, since I only have a 4 prime. I am a clear favorite with outfield control but he can always roll an escaping joker. How often would I estimate I win after a hit? Let's call it 75% of the time, depending on whether he fans, or comes in with a 25 16 26, or comes in with a stuck 1 or 2. This is fairly conservative since I will redouble which 1) ends many games [or even if he takes I can basically count it as a win, since I get leverage] and 2) kills gammons against me.
54 and 63 are very good for him, leaving only 11 shots. If he rolls a 9 then I wish I had passed.
8s are 2nd best for him, after the gin numbers, leaving only 9 shots. He has 4 8s.
7s are also pretty good, but they leave 15 shots. There are 4 7s. 10s also leave 15 shots and there are 2 of those (since we counted 55 as gin earlier).
Let's say I hit 1/3 of the time in those 14 games. That means 4 2/3 games I hit.
What happens when he rolls his other numbers? 33 is blocked, 44 is blocked, 43 is blocked. 51 41 31 21 11 and 22 32 42 all don't get past. How many numbers is that? That is 18 numbers. (pretty sure I got all 36 now). In those 18 numbers I am shooting at a triple shot, actually. There rate to be 27+ hits. Sometimes when I miss I get a repeat shot (like when he rolls a blocked 33 44 43), but sometimes when he rolls a number like 51 and I miss I rate to get gammoned.
So how many hits in those 18? Rather than count every permutation, let's be very conservative and say I only hit 75% of the time of those 18. That would be 13.5 hits there, plus the 4 2/3 from earlier, giving me about 18 hits total in 36 games. Of those I win 75%, so call that 37.5% total wins.
If I won 37.5% games for money and all my losses were gammons and I had no recube value, I would have a pass. But if only 70% of my losses were gammons and I could get a recube in sometimes, then I should have a close decision.
It certainly looks like I will be able to save the gammon 30% of the time when he rolls a number like 65, and quite often in the games where I hit and he manages to escape somehow (although of course the cube gets to 8 quickly). Also I estimated everything conservatively towards the pass side so if I still come up with a take with conservative estimates then it should be a clear take and I can't really pass.
Basically no matter how you slice it working out the numbers leads to a take. The only time I really have to use positional judgment is in how many games I win after a hit, since it's not 100%, and how many times I can redouble.
Of course I haven't answered the question of whether to redouble or not, since it's not my problem. However given that several players would just drop this like a rock, and since many of the world class players I asked quickly came up with double/pass, I do think that you should just double and let the other guy figure it out (or just guess wrong).

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