Hi, forum is pretty quiet lately with Yogi pursuing romance, so I thought I would post this. What are the factors that swing you to one of the two obvious plays?



There is a pretty big difference between the two... (.087)

Against making the 5:
- (big one) we leave our 18pt. blot exposed to opp's ugly midpoint stack, which allows him to unload it with a tempo (the bigger the stack the worse leaving blots in front of it is)
- (medium one) race is close, so we don't want to get hit
- (small one) we block only one checker instead of two
- (small one) it's OK for attacking plan (a lone checker can't anchor up), but this plan is sort of muffled by the fact that opp owns his 5pt. too

I go with 24/18.

Good problem. This is the kind of situation that occurs all the time, and understanding the reasoning behind the correct play will really help improve your game.

First, I think it really helps to have a mental classification system, so you can orient yourself before you even start weighing the alternatives. In this case, the broad category is ‘The Opening’ (because only a couple of new points have been made and the inner boards are still weak), and within that we have one of our basic choices: ‘5-point or 18-point’?

Next big question is “What’s my default here?” I’ve got a couple of dozen positions in my database that are either ‘5-point versus 18-point’ or ‘5-point versus 20-point’ and in 2/3 of these problems making the anchor is right. So if I can’t sort things out over the board, my default play will be 24/18.

Now it’s time to look at the specific features of this position. Here’s what I see.

Inherent Strength of Point. Both the 5 and the 18 are great points. But Black only has one checker back, so the value of the 5-point goes down a bit. Black also has a lot of ammo aimed at the 18, so its value goes up a bit. Edge to the 18.

Distribution of Checkers. White is well-distributed after making either play. He doesn’t have any big stacks or awkwardly placed builders. No edge here.

Blots. Making the 5-point leaves two blots which are easy to hit, while making the 18-point leaves one blot which is hard to hit. Big edge to making the 18-point.

Opponent’s Distribution. Making the 5-point leave Black with a big stack on the midpoint, and if he rolls a six he can both unstack and hit. Big edge to making the 18-point.

Race. White leads by 8 pips after the play, implying he wants fewer blots and less downside risk from being hit. Big edge to making the 18-point.

Put all the pieces together, and making the 18 is so far ahead that making the 5-point is probably a blunder or close to it.

WOW, Outstanding analysis Bill. Have you considered joining CSI?

Keep it under your hat. I've been consulting with CSI-Boston for some time now.

Spotting the factors isn't that hard. Weighing them correctly is, and takes years of experience. After reviewing some variants I conclude, that I've greatly underestimated the importance of opp's 5 pt. and overestimated his midpoint stack's unloading urgency, and the race.

Here is the bleep's original position:



Making the 18pt. is correct by .122 (acc. to XGR++).

There are many factors pointing to that play, which made it rather easy to pick. But the hierarchy should probably go more like this:
- (big one) making the 5, which is the attacking/priming play fights only one opp's checker instead of typical two
- (big one) presence of opp's golden point makes his frontal position strong, so we should be looking to anchor up to avoid hits
- (medium one) opp's big midpoint stack represents inflexibility in his position, so we shouldn't let him bypass this problem with an unloading tempo hit
- (small one) race is close, so reducing hits is thematic

Take a look at contrasting variant A (in comparison to the original position, top player is adjusted 5/6 5/8):



Making the 5pt. is correct by .035 (acc. to XGR++).

If You look at the above list, one of the big ones is gone (opp's 5pt.). Suddenly, You don't have to fear the hits having 3pt. vs 1pt. boards (note, that only 61, 11 and 33 are safe hits for the opp, the rest leaves quite a bunch of returns). Also, because opp's frontal position is undeveloped, there is no need to look for an anchor yet. Making the 18 would let him play into his home board safely, too.

Another variant, contrasting with the original position is variant B below (in comparison to the original position, top player is adjusted 13/23):



Making the 5pt. is correct by .026 (acc. to XGR++).

Again, one of the big factors changes, as our 5pt. is now attacking/priming two opp's checkers instead of just one. The change in opp's midpoint stack from 6 to 5 guys is just a minor thing, as well, as the race (note, that we are 18 pips ahead after the play, and yet, leaving the blot on opp's bar point for more shots is fair).

Thanks for the detailed explanations Karol and Robertie. It sounds so simple after reading through them. What makes it so tricky is missing just one of the factors quite dramatically alters the score of the move!

Interesting. Positions/rolls with multiple good alternatives can be tricky.

Bill gives a thorough analysis. The two big factors for me are 1) blot coverage, and 2) with only one man back, black cannot anchor on my 5 point anyway. I can expect to make that point at my leisure in the near future.

Wow. What an awesome thread. Learned a lot just by reading it.

I'm new here, but to me, the two plays are so close. When I am encountered with these types of close decisions, often times the read I getting from my opponent will dictate my play.

If an opponent is starting to tilt or get a little reckless, then I will make the more conservative play. If they have been playing tighter, then I go on the offensive.

I don't recommend trying to adjust your checker play when your opponent is on tilt. It's often hard to simply figure out what the right play is, let alone try to figure out when making a checker mistake will actually be more profitable.

Assuming you could figure out the best play and the second-best play with accuracy, I would recommend making the more aggressive, not the more conservative, play when your opponent is on tilt. The aggressive play is usually more likely to lead to unbalanced positions with more difficult cube decisions, which is exactly where a steaming player will make his biggest errors.