Author: Michael Yee
Date: 05:52:20 05/25/05
Go up one level in this thread
On May 25, 2005 at 06:07:00, Vasik Rajlich wrote:
>On May 24, 2005 at 18:49:05, Michael Yee wrote:
>
>>ACM/CSC-ER,
>>Proceedings of the 1983 annual conference on Computers : Extending the human
>>resource
>>
>>I just read this interesting paper (20+ years later!)...
>>
>>Main idea:
>>
>>Schaeffer essentially computes piece square table "bonuses" that depend on the
>>root position (e.g., plans like "king-side attack" or "try to occupy f5 with
>>your knight") and get added to the score of a branch in a path dependent way.
>>
>>Some questions:
>>
>>(1) Is this what Vincent Diepeveen sometimes referred to as "root processing"?
>>
>>(2) Does anyone know how Schaeffer's Planner compared to Wilkin's PARADISE (in
>>terms of playing strength)?
>>
>>(3) Is anyone experimenting with this or other types of path dependent eval?
>>
>>Steven is of course working on long-range planning. And I think Uri has some
>>path dependent stuff. But have most people pretty much abandoned it?
>>
>>Thanks,
>>Michael
>
>Just a terminological point - every engine does "long-range planning" by virtue
>of having an evaluation function.
>
>You could easily make a 1-to-1 mapping between any type of work done at the root
>and a pure static evaluation at the leaf.
>
>Vas
I had a similar thought about folding everything into the static eval. (After
all, each feature is really encoding a plan: get a lead in material, get a
better pawn structure, attack opponent's king safety, etc.)
But I think the mapping isn't exactly 1-to-1. Here's Schaeffer's bonus table for
getting a N on c1 to f5:
+---+---+---+---+---+---+---+---+
8 | | | 4 | | 4 | | 4 | |
+---+---+---+---+---+---+---+---+
7 | | 4 | | | 8 | 4 | 8 | |
+---+---+---+---+---+---+---+---+
6 | | | 4 | 8 | 4 | | 4 | 8 |
+---+---+---+---+---+---+---+---+
5 | | 4 | | 4 | | 16| | 4 |
+---+---+---+---+---+---+---+---+
4 | | | 4 | 8 | 4 | | 4 | 8 |
+---+---+---+---+---+---+---+---+
3 | | 4 | | | 8 | 4 | 8 | |
+---+---+---+---+---+---+---+---+
2 | | | 4 | | 4 | | 4 | |
+---+---+---+---+---+---+---+---+
1 | | | N | 4 | | 4 | | 4 |
+---+---+---+---+---+---+---+---+
a b c d e f g h
For example, the path "N-e2-g3-f5" yields 4 + 8 + 16 = 28 bonus points (after
which, the "get N to f5" goal might shut off, I think?). This can certainly be
put in the static eval itself since you could have partial sums: each 4 would
still be 4, each 8 would become 12, and the 16 would become 28.
However, if you add some negative bonuses, say on a2 and c3, to penalize wasting
time, I don't think you can model it exactly with just the static eval anymore.
+---+---+---+---+---+---+---+---+
8 | | | 4 | | 4 | | 4 | |
+---+---+---+---+---+---+---+---+
7 | | 4 | | | 8 | 4 | 8 | |
+---+---+---+---+---+---+---+---+
6 | | | 4 | 8 | 4 | | 4 | 8 |
+---+---+---+---+---+---+---+---+
5 | | 4 | | 4 | | 16| | 4 |
+---+---+---+---+---+---+---+---+
4 | | | 4 | 8 | 4 | | 4 | 8 |
+---+---+---+---+---+---+---+---+
3 | | 4 | -1| | 8 | 4 | 8 | |
+---+---+---+---+---+---+---+---+
2 | -1| | 4 | | 4 | | 4 | |
+---+---+---+---+---+---+---+---+
1 | | | N | 4 | | 4 | | 4 |
+---+---+---+---+---+---+---+---+
a b c d e f g h
N-a2-c3-e4-g3-f5 --> -1 + -1 + 4 + 8 + 16 = 26 bonus points
N-e2-g3-f5 --> still 28 bonus points
Both end positions could be the same (say, if the opponent moved a R and put it
back, but would have different path dependent evals.
If the above example is correct, then maybe it shows that "path dependent"
bonuses can help deal with time/tempo.
Michael
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