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Backwards capture position

Public forum discussion.

Einstein

#3 · lorentz

1 Nov 2011

That is cute. It reminds me of some chess endgame positions where a king must maintain the opposition from a distance.

#4 · Dvd Avins

1 Nov 2011

At first glance, I believe that would be the only winning move in standard EWN, too, for slightly different but related reasons.

#5 · hanfried_c

1 Nov 2011

No, in standard EWN this position is lost for the first player.

If I made no mistake this is the only symmetrical position which is lost in a two-stone-endgame.

#6 · Ingo Althofer

2 Nov 2011

> No, in standard EWN this position is lost for the first player.

> If I made no mistake this is the only symmetrical position

> which is lost in a two-stone-endgame.

The father of sybil_c should be able to shed more light on this.

He seems to have complete Ewn databases for all positions with up

to seven stones.

Sybil_Dad, can you hear us???

Ingo.

#7 · sybil_c

2 Nov 2011

I agree with Hanfried. All the other symmetric positions are a win for the player to move. By my quick calculation, there aren't any symmetric 4-stone positions in which the player to move is dead-lost, but there are several in which the player to move is clearly worse. What's interesting is how similar the very worst such 4-stone position looks to the lost 2-stone position.</ br>

<br/>A - - - -
<br/>- - - - -
<br/>6 - - - -
<br/>- - - - -
<br/>- - F - 1
<br/>

The player to move should lose this position just over 5/6 of the time.

#8 · sybil_c

2 Nov 2011

Ahh... I should spend more time thinking before I post. Hanfried seems to have considered only rotational symmetry, and I'd only considered mirrored. Turns out there's one (after collapsing symmetry along the diagonal) lost to-move 2-stone position from each:

<br/>- - - - -   - A - - -
<br/>A - - - -   - - - - -
<br/>- - - - -   - - - - -
<br/>- - - - -   - - - - -
<br/>- - - 1 -   - - - 1 -
<br/>