My greatest misses: overestimating getting blitzed

 In this match against XG Mobile I made a horrible mistake, and one that took me a long time to even understand.

White to play 41.

So what do you think? Play it safe or split the back checkers and try to run?

My reasoning was: Black has 11 men in the zone, if I split now with 23/18, he will build a big board or prime and just kill me. Better play it safe and wait for a good roll to bring my back men home. So I played 9/8, 9/5 and was very proud of this move that gave me much flexibility in the next rolls.

XG2 said: -0.46. Biggest blunder in weeks, recommending 23/18. 

That really was a WTF moment for me - splitting my back checkers against so many of his builders? Running into a 4-way attack? The only numbers that don't hit me are 55 and 25. 

Only once I played 10 games from this position I noticed the difference: black is closing in fast. If I don't act now it will build a strong prime in the next moves. But if I split and endure his hit, I have some good fighting chances because of its weaker inner board. Many hits give me return hits.

The lesson this taught me: don't overestimate the opponent's blitzing chances if their board is weaker than yours. Is that the lesson? Hm.

Watch them UBC videos!

Hi everybody,

If you have plenty of time to spare (supposedly there's a certain virus that gives us all kinds of free time that we formerly spent partying and such) and want to improve your backgammon, then have a look at the UBC (ultimate backgammon championship) videos on youtube.

These videos are well-produced, feature great commentary by backgammon grandmasters + analysis by XG; the games are very dramatic at times, and best of all: this is a "backgammon galaxy" style format: Players play several matches to 7 points, and get a point for winning a match, and a point for having played with the lower PR. This way the players spend much time thinking about the best move, and the grandmasters commenting spend this time discussing why this or that move is good or bad. GREAT learning.

Here's the really fun match of Mochy vs. Sander Lyloff  

• Day 1
  
• Day 2
• Day 3

And day 1 of the 2020 tournament (not that spectacular matches but much to learn from)

To hit or not to hit?

Recently I came across this position when playing Gnu Backgammon:

 

 

White to play 65

 

I thought that the big decision is: hit with 13/2* or play it safe with 13/8, 9/3. I hit on the 2, reasoning that I'm only slightly ahead in the race (4 points before the move), I have the stronger board, and gnubg has two blots in his home board, so if it manages to re-enter and hit me it should not be able to consolidate its board. I concluded that I'm well ahead if I hit.

On the other hand, if I play it safe I have no blot, but I risk that after 62, 55, 54, 53, 52, 44 gnubg gets out. That's 10 rolls that make the game even.

So I played the big blunder 13/2* (-0.21 equity compared to 13/8, 9/3, according to XG2's rollout).

Here's the dice distribution of gnubg rolls after my two moves:

 

Rolls after the best move, 13/8 9/3. Only 55 is dangerous (bringing gnubg's blot to safety)

 

 

Rolls after my move, 13/2. If gnubg hits me with a 2, XG considers me no longer a favorite.

Seems I overestimated the danger of gnubg escaping when I play safe - only a 55 diminishes my significant lead. I also underestimated my winning chances. I was expecting a small lead like 0.2, not the 0.8 XG assesses. 

My hitting move makes gnubg a favorite if it hits. That's also something I didn't expect. But if you actually look at the positions after every move 2+x, it shows that gnubg can always cover one of the blots and make a three-point board itself, giving us an almost symmetrical position (and costing me 23 pips in the race, obviously).

The basic lesson I learned: with a big roll like 65, don't consider the pipcount before but after the move. I was not 4 pips ahead but 15, which is quite a lead and which suggested a conservative play.