Re: [gnugo-devel] Opponent follow-up value and group connection

[SP LEE]

You are right. I was afraid that this solution was too simple as well. Is
there a good way to tune the valuation system? And is the value equal to
point?

SP Lee


----- Original Message -----
From: "Evan Berggren Daniel" <address@hidden>
To: "GNU Go development" <address@hidden>
Sent: Monday, May 12, 2003 12:53 PM
Subject: Re: [gnugo-devel] Opponent follow-up value and group connection


> It seems to me that this patch is going in the wrong direction.  The
> problem you're trying to solve is that GNU Go fails to attack or defend
> large groups, even when it knows that the group is critical.  However, I
> think that in many cases GNU Go's valuation of the attack or defense move
> is perfectly correct.  It is that the tenuki plays are overvalued, often
> by very large amounts.  Forcing GNU Go to defend a large dragon simply
> because it is large might help in the short run, but in the long run we
> want to fix the real problem, which is the tenuki valuation.
>
> To give some more concrete reasons: would you want GNU Go to automatically
> defend a 16 point group?  a 12 point group?  an 8 point group?  What if it
> has time to defend either a 14 point group or a 16 point group, but the 14
> point group can be defended in a way that weakens an opponent's group?
> Maybe the fact that it weakens the opponents group is only worth a few
> points, but then the 14 point group is more worth defending.  The decision
> is not clear cut, and the only reasonable solution in the long run is to
> have GNU Go evaluate each move, and pick the largest one.  Clearly, for
> this to work, GNU Go must evaluate all the moves correctly.
>
> Evan Daniel
>
> On Mon, 12 May 2003, SP LEE wrote:
>
> > The following patch is to make GNUGO to treat bigger dragons more
seriously.
> > I'm not experienced in making such patches, so please correct me if I'm
> > wrong.
> >
> > --- gnugo/engine/value_moves.c 2003-05-12 12:08:30.000000000 -0700
> > +++ value_moves.c 2003-05-12 12:09:34.000000000 -0700
> > @@ -1767,7 +1767,16 @@
> >        if (move_reasons[r].type == OWL_ATTACK_MOVE
> >     || move_reasons[r].type == OWL_DEFEND_MOVE
> >     || move_reasons[r].type == SEMEAI_MOVE)
> > - this_value = 0.0;
> > +   {
> > +    /* For bigger dragon an extra weight is added */
> > +   if (this_value>16)
> > +   {
> > +    tot_value+=this_value;
> > +    TRACE("  %1m: -%f - owl attack/defense of big dragon %1m\n",
> > +     pos, this_value, aa);
> > +   }
> > +   this_value = 0.0;
> > +   }
> >        else if (move_reasons[r].type == OWL_ATTACK_MOVE_GOOD_KO
> >          || move_reasons[r].type == OWL_DEFEND_MOVE_GOOD_KO) {
> >   this_value *= 0.3;
> >
> >
> >
> > ----- Original Message -----
> > From: "SP LEE" <address@hidden>
> > To: <address@hidden>
> > Sent: Sunday, May 11, 2003 9:31 AM
> > Subject: Re: [gnugo-devel] Opponent follow-up value and group connection
> >
> >
> > > The solution to this problem might be simple, but it certainly has
good or
> > > bad effect in general. If I have a group worth more than 15 points, I
> > would
> > > not trade it for something else easily. So we could double the "change
in
> > > territory" value if it's greater than 15.
> > >
> > > I don't know if this is a good solution. Please comment.
> > >
> > >
> > > >From: Arend Bayer <address@hidden>
> > > >Reply-To: GNU Go development <address@hidden>
> > > >To: GNU Go development <address@hidden>
> > > >Subject: Re: [gnugo-devel] Opponent follow-up value and group
connection
> > > >Date: Sun, 11 May 2003 15:05:57 +0200 (CEST)
> > > >
> > > >On Sat, 10 May 2003, SP LEE wrote:
> > > >
> > > > > Then at move 166, GNUGO played M6, letting the lower right corner
> > group
> > > >T7
> > > > > dead by white O6, losing about 30 points. It is interesting that
the
> > owl
> > > > > analysis of T7 is completely correct. It said that T7 is dead if
white
> > > >plays
> > > > > O6 and the defend of T7 is possible at O6.
> > > > >
> > > > > Below is the top moves GNUGO considered:
> > > > >
> > > > > Top moves:
> > > > > 1. M6  36.76
> > > > > 2. O6  36.11
> > > >
> > > > >
> > > > >   M6: owl attack/defend for L6
> > > > >   M6:   2.83 (followup) - threatens to capture M5
> > > > >   M6: 11.17 - change in territory
> > > > >   M6: 3.87 - strategic effect on L8
> > > > >   M6: 8.17 - strategic effect on N7
> > > > >   M6:   3.94 - L6 strategic value already counted - A.
> > > > >   M6: 8.04 - strategic effect on K5
> > > > >   M6:   2.83 - total followup value, added 0.00 as territorial
> > followup
> > > > >   M6: 1.42 - added due to followup (2.83) and reverse followup
values
> > > >(0.00)
> > > > >   M6: 3.35 - shape (shape values +2.00(1) -0.00(0), shape factor
> > 1.102)
> > > > >   M6: 0.74 - connects strings (connect value 7, shape factor
0.149)
> > > > > Move generation values M6 to 36.75
> > > > >
> > > > >   O6: owl attack/defend for T7
> > > > >   O6: 29.81 - change in territory
> > > > >   O6: 3.13 - strategic effect on N7
> > > > >   O6: 2.48 - strategic bonus for T7
> > > > >   O6:   4.33 - total followup value, added 4.33 as territorial
> > followup
> > > > >   O6: 2.16 - added due to followup (4.33) and reverse followup
values
> > > >(0.00)
> > > > >   O6: -1.79 - shape (shape values +0.00(0) -1.00(1), shape factor
> > 0.952)
> > > > >   O6: 0.31 - connects strings (connect value 3, shape factor
0.061)
> > > > > Move generation values O6 to 36.10
> > > >
> > > > > I would think if a group is dead and worth 30 points, GNUGO must
> > > >consider it
> > > > > seriously.
> > > >
> > > >Yes, the problem here is that the strategic valuations of M6 got a
bit
> > > >confused. One problem is the dragon at K5. It can either connect to
> > > >H6 or to K9, and so M6 should get hardly any "strategic effect" bonus
for
> > > >that.
> > > >
> > > >Also the shape values don't exactly help here.
> > > >
> > > >Arend
> > > >
> > > >
> > > >
> > > >
> > > >_______________________________________________
> > > >gnugo-devel mailing list
> > > >address@hidden
> > > >http://mail.gnu.org/mailman/listinfo/gnugo-devel
> > >
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> >
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