Recommend
4 
 Thumb up
 Hide
8 Posts

Twixt» Forums » Strategy

Subject: A corner battle that turns into a draw rss

Your Tags: Add tags
Popular Tags: [View All]
David Bush
United States
Radiant
Virginia
flag msg tools
designer
badge
Avatar
mbmbmbmbmb
Drawn positions comprise less than 1% (my estimate) of completed games. They can happen when one player makes a "wall" which blocks the opponent, but this wall is not a continuous chain of linked pegs. Here is a corner position, modified from an actual game, which leads to a local draw with best play by both sides.



I call the dark pieces black and the light pieces white. A colon at the end of a remark means the following image is of a sub-optimal variation. A period indicates the image is of the main line. I'm not sure how this position could ever arise in an actual game. Black to move makes the natural move, which I call a hammer attack.



It might seem that white could defend with U19:



But black can win immediately with W19:



Instead, the best defense for white is to play at W19.



Now it might seem that black should also switch places with white from the earlier variation, and attack at U19:



But this loses against V20:



Now T17 looks crushing for black, but it's just an illusion:



White wins here with the brutal U18:



Black should not have attacked at U19. Instead, the crucial variation is for black to play V21.





















Black is blocked from forming a winning path. Consider the white peg at U19. There is no way that it could connect to the lower group, nor can it connect to the bottom border. The only path that white might be able to use to win would pass through the two holes shown in red. But if white plays at one of these holes, black can play at the other, blocking white. So this is a locally drawn position.

I welcome any question or comment.
5 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
Tim Schmitt
United States
South Portland
Maine
flag msg tools
badge
Avatar
mbmbmbmbmb
I appreciate this post, though I've not played Twixt in many years and I'm sure your knowledge of strategy is far beyond mine.

Most of this makes sense to me, but I'm not sure I understand why V20 is white's natural response to black's V21. What could black do if white plays at S21? Would T17 be the killer for black at that point (because White can't block both U19 & U15 which may both be winners for black in that situation)?

Thanks!
2 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
David Bush
United States
Radiant
Virginia
flag msg tools
designer
badge
Avatar
mbmbmbmbmb
If white plays S21



Then yes, black can win with T17 threatening U19 (double linking) or V16. (U15 would not be so good.)



Black could win just as quickly with U18 instead of T17.



Then if white blocks with V17, black could play V20. (T20 double linking would also work.)



Oh, and thanks for asking a question!
3 
 Thumb up
0.02
 tip
 Hide
  • [+] Dice rolls
Maciej Celuch
Poland
flag msg tools
Another good puzzle. It seems that it's really a draw!

Another try for black could be u.22 (after white's w.19) but white can respond v.21, which is probably the only one move for white to win.
2 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
David Bush
United States
Radiant
Virginia
flag msg tools
designer
badge
Avatar
mbmbmbmbmb
Thanks for checking! Readers might like to know that Maciej is my nemesis. He's probably the strongest human Twixt player.

Maciej, you might like to know that I got the idea from a variation I looked at in our most recent game, where this pattern cropped up:


At first, I thought black's best move in this corner would be S19, and I thought "hey that's cool, that would turn into a draw" but later I realized black could actually win here. So this is a puzzle for the public. How does black to move take the corner here?

Solution
1 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
Maciej Celuch
Poland
flag msg tools
Hey,

In this case it's probably only one move for black to connect to the right edge.

But I don't understand one thing here. Why white player wants to play T16?

Why not V16

or U17


Then black can't connect right edge.

Kind Regards,
Maciej
 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
David Bush
United States
Radiant
Virginia
flag msg tools
designer
badge
Avatar
mbmbmbmbmb
nie_wiesz wrote:
Hey,

In this case it's probably only one move for black to connect to the right edge.

But I don't understand one thing here. Why white player wants to play T16?

Why not V16

or U17


Then black can't connect right edge.

Kind Regards,
Maciej

In the variation I looked at, outside of the region shown, black had a peg on R12. White wants to keep black from playing T16 which would include the threat to double link to his R12 peg.

Board game geek is not very user friendly for new posters who want to add images. You could edit your post to add the word "original" which refers to the image size. For example
{imageid=3862193 original} with square brackets instead of curly ones. Not that it matters of course.
 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
Maciej Celuch
Poland
flag msg tools
I see, R12 was the reason.

I have another puzzle, which I have found during some experiment on this case.



Find a move for white to win.

1 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
Front Page | Welcome | Contact | Privacy Policy | Terms of Service | Advertise | Support BGG | Feeds RSS
Geekdo, BoardGameGeek, the Geekdo logo, and the BoardGameGeek logo are trademarks of BoardGameGeek, LLC.