RE: computer-go: "The value of sente"

["Tim Hunt" <timhunt@xxxxxxxxxxxxxxxxxxxxxxx>]

> >>Could someone please define "the value of sente?"   Thanks.
>
> > With good play it is about 15 at the start of the game, and falls
> > (though not quite monotonically) to 0 at the end of the game.  With poor
> > play, it is somewhat smaller.
>
> The first move is considered to be worth about 5-6 points. Sente
> cannot be more than that.
> But it may be higher for later moves and the fall again ... I don't know.

No, Suppose that the value of a typical move in the opening is m. The value
of the empty board is 0, since it is symmetrical with respect to the two
players. Then the value of the position over the first few moves is going to
be:

                  Value
Start             0
      Black plays
After move 1      m
      White plays
After move 2      0
      Black plays
After move 3      m
      White plays
After move 4      0

Now this is unfair, since it oscillates between 0, which is even, and m,
which is favourable to black.

To make things fair we award k points komi to white, so the values go:

                  Value
Start             -k
      Black plays
After move 1      m - k
      White plays
After move 2      -k
      Black plays
After move 3      m - k
      White plays
After move 4      -k

This will be fair if m - k = k, or if m = 2*k.

Since komi is normally 5.5 or 6.5, this suggests m is about 11 or 13.

Tim.


(P.S. For CGT/mathematician type people: by value I mean "mean value" for
positions, and miai value for moves. If you don't understand this forget it.
This argument is made more rigorous by "sentestrat". Read the papers in
"Games of No Chance").