[ View Thread ] [ Post Response ] [ Return to Index ] [ Read Prev Msg ] [ Read Next Msg ]

BGonline.org Forums

Yes, it's Possible

Posted By: Nack Ballard
Date: Friday, 18 December 2015, at 2:51 a.m.

In Response To: So many options (Timothy Chow)





White is Player 2

score: 0
pip: 136
1 point match
pip: 163
score: 0

Blue is Player 1
XGID=-a---BDBa---bDA--ccd----AA:0:0:1:42:0:0:0:1:10

Target Position.. (White has one checker off)


Did White really manage to bear off a checker before getting to this position?

Calling Nack to find a perfectly played retro-sequence!


Definitely doable, but a lot of work. I'll outline an archetypal retro-solution. (For convenience, XGR++ evaluation will be the "perfect play" arbiter.)






White is Player 2

score: 0
pip: 156
1 point match
pip: 204
score: 0

Blue is Player 1
XGID=----aaD-B---cDb--c-e-BA-B-:0:0:1:43:0:0:0:1:10

Blue to play 43


Without much effort, we can get from the opening position to a position like the one diagrammed above. Blue's best play with 43 is to hit twice, which forces White to hit two checkers back with 54.

Blue now enters with just a 3 (still leaving a checker on the bar), making a third anchor in white's board:






White is Player 2

score: 0
pip: 156
1 point match
pip: 235
score: 0

Blue is Player 1
XGID=----aaD-----cDb--c-e-BB-BA:0:0:-1:55:0:0:0:1:10

White to play 55


White now rolls 55, with which she should play 21/16 20/5 (though her exact play doesn't really matter). She then rolls double 5s twice more followed by double 2s twice, while Blue repeatedly fans. Then White (with all 15 checkers on her 6pt) takes one checker off with 42, to reach this position:






White is Player 2

score: 0
pip: 83
1 point match
pip: 235
score: 0

Blue is Player 1
XGID=------D------D-----maBB-BA:0:0:1:55:0:0:0:1:10

Blue to play 55


Phase 2 begins. Blue will now hit, then set up a little blockade, so that bad rolls will force White to expose more checkers.

For example, say Blue rolls 55 and plays bar/20*/15 13/8(2), white fans, and Blue makes his 5pt with 44. Then White rolls 41, her best play being bar/24 6/2, as shown in the next diagram.

[This is not the specific sequence I recommend, because it will involve extra length or precision to build and restack the midpoint later. I'm choosing this sample sequence only because it demonstrates Phase 2 quickly.]






White is Player 2

score: 0
pip: 98
1 point match
pip: 199
score: 0

Blue is Player 1
XGID=-a---BD-B------A---l-BBaB-:0:0:1:21:0:0:0:1:10

Blue to play 21



Now Blue hits with an ace (say 21, played 24/23* 15/13), White hits back on her 1pt (forced) with either 51 or 53, Blue hits bar/24* with an ace, white hits back 6/1* with another 51 or 53, Blue hits bar/24* again (if necessary with 61 or 11 to force Blue to hit), etc., until White has eleven checkers back and four checkers on her 6pt.

Then phase 3 begins. White is able to get some checkers out, by hitting fly shots and/or making temporary outfield points, until she eventually makes her own 7pt and 8pt. Ultimately we reach the target position (what appears to be a middle game position with one White checker accidentally off) diagrammed at the beginning of this post.

Nack

Messages In This Thread

 

Post Response
Your Name:
Your E-Mail Address:
Subject:
Message:

If necessary, enter your password below:

Password:
 

 

[ View Thread ] [ Post Response ] [ Return to Index ] [ Read Prev Msg ] [ Read Next Msg ]

BGonline.org Forums is maintained by Stick with WebBBS 5.12.