Re: [gnugo-devel] move valuation

[Inge Wallin]

Arend wrote:
> So the following is just a theoretical discussion, but since I raised
> that matter I feel I should explain why I think so: Let's look at the
> following position:
> |..XXXXXXXXX...
> |XXXOXOOOOOXXXX
> |XOXOXO.O.OXOOX
> |.OaObO.O.OcOOX
> +--------------
> First note that all moves here are gote.
> Your method values a white move at b with 7 pts (after white moves there,
> black will be assumed to play at a). A white move at c is worth 8 pts.

No.  It will be valued as 7 points of territory value and 5 points of
followup value.  (In this case, I am not sure that the followup value
is really caught but if b is found as a threat to save the two white
stones, it will be.)  This will give:

  total value = 7 + 0.5 * 5 = 9.5 (just what you valued the move to)

> As another example, the move
> OXXXX
> O*..X
> is valued as 1pt by GnuGo (instead of 1.5).

It is? Have you checked this?  In that case, a simple pattern that
generates a followup value of 1 point should be simple to generate.
For a number of examples like this, look in patterns/endgame.db.

> Also, one can work around this with follow_up values, which as I
> understand GnuGo does rather rarely.

Yes, like I describe above.  It was me that introduced the followup
and reverse_followup values and my intention was that we produce them
for lots of situations by patterns or by code.  Examples right now are
that threats to save or capture a string gets followup values and a
number of patterns in endgame.db are assigned to only provide followup
values for common situations.  There should be a lot more of them.

But the real weakness is (as I also said above) that there is no real
notion of sente and gote sequences.

        -Inge