Monday, 13 February 2012
Backwoods v. zyxtcba part 4
Two questions left over from the last post and here's the first, with Black leading 6-4 to 13.
Black (zyxtcba) went for 20/10, encouraged by those two blots that White has in his homeboard no doubt. Some knowledgeable commenters also liked this, but it's a blunder. At present, this is a positional struggle, with Black holding a clear advantage. He has much the better anchor and all his checkers are in play. White on the other hand has four checkers already behind Black's 20pt anchor. These are useless for priming but can suddenly become useful if this turns into a hitting contest. Abandoning the anchor initiates exactly that sort of game. My own personal rule is, if it isn't obviously right to run, choose something else! So, what else? Some commenters and also XG++ like 13/7, 13/9, an ambitious attempt to build a winning prime at the cost of two blots. Old Skool masters liked this sort of play a lot, reasoning that if you own the 20pt, you can put your checkers where you want them and damn the torpedoes. It's actually still a very sound guideline and I can imagine a world class player making this play. The other contender is 13/3, less ambitious but it retains the midpoint and the anchor and forces White to quit his anchor if he wants to hit. Subtly it also activates the two spares on Black's 6pt to do something useful. I like this a lot, moving steadily towards a winning prime with little risk. A 2592 game 3-ply rollout also makes this a small but not definitive favourite. It's hard to spot like so many quiet strong plays. Humans are hard-wired to take positive action to deal with a problem now, but in backgammon, keeping all your options open and adopting a quieter approach is often as good or better. Erroll Flynn had the big style, much preferring to swing in to the banqueting hall on the chandelier, but one wonders whether walking quietly down the stairs wouldn't have served as well. An interesting and instructive position.
White (Backwoods) also had a roll that is commonly mishandled by beginners. Here it is.
Sadly Backwoods chose the beginner play, 23/22, 13/7 but hitting on the ace is absolutely clear. White must take advantage of his stronger board and go for the gammonish closeout. This is not an isolated case. It's worth taking a bigger risk than this to try for a closeout and here it is so important to stop Black making an anchor on the ace that White should probably hit there even if he knows that Black is about to roll a one! This also comes up a lot, well worth remembering.
Other news. We're into the last two weeks of Fibs League session 55 and both Master A and Master B are coming nicely to the boil. In Master A your correspondent has 8-3 with one match to play, but everybody else has played fewer matches and nine other players can still put a run together and equal or surpass this score. In Master B Germany's runnerup is 8-4, also with one match to play (Master B has 14 players in this session) but again, most of the division will still be hoping for a burst of form to catch or pass that.
The 2011 Master Playoffs kicked off, with Schigolch (Germany) winning his first match with Mano (France). All these ties are best of three 9 pointers.
A word about rollouts. This blog attracts some mild criticism because I don't post the results of rollouts. It may be useful for you to know that I use XG for this, with 3-ply checker play. It's possible, likely even, that a higher level of play can produce a different result, but you do have to remember that players who can play as well as XG 3-ply are few and far between, so by using more advanced settings, you move into areas where no human can play well enough to achieve the theoretical equity. As the differences usually amount to a few hundreths of a point of equity, the value of a more accurate answer is limited anyway. I've also found that posting rollout results is boring and counter-productive, as they stifle debate. I would rather listen to our correspondents discussing why they would make a play any day, even if they are wrong!! Backgammon isn't about knowing what the right answer is, it's about knowing why the right answer is right, so that when in future we meet something like it, we have something to base a play on.
Anybody can do rollouts and I am always pleased to hear from somebody who has rolled out a position from here and got a different answer, but I won't be posting mine.
I'll have some more action from Backwoods v. zyxtcba tomorrow, perhaps even later today, so stay tuned. Until then, enjoy the game!