Author: Dann Corbit
Date: 01:38:01 04/14/04
Go up one level in this thread
On April 14, 2004 at 04:26:10, Richard Pijl wrote:
>On April 14, 2004 at 03:49:06, Dann Corbit wrote:
>
>>On April 14, 2004 at 03:46:08, Richard Pijl wrote:
>>
>>>On April 14, 2004 at 03:30:22, Dann Corbit wrote:
>>>
>>>>I decided to toss an MTD(f) search into TSCP, and I've got something wrong, but
>>>>I can't quite see what it is.
>>>
>>>MTD(f) requires a transposition hashtable and a fail-soft search to function
>>>properly. Did you add/change that too?
>>
>>With hash table, I get this behavior:
>>post
>>sd 99
>>st 99
>>go
>>Depth Eval Time Nodes PV
>>1 48 0 172
>>2 0 20 2224 d2d3
>>3 35 40 4858
>>4 5 321 41505 e2e3
>>5 35 711 93485
>>6 13 5438 780563 d2d4
>>7 30 11878 1638246
>>8 18 81509 11563089 e2e4
>>move e2e4
>>
>
>I guess you're referring to the empty PV lines?
>That's normal, as TSCP doesn't store the PV on a fail high/low. As TSCP is
>searching with an open window in the root, you will always have a PV. But with
>MTD(f) you're searching with null-windows, so you won't have a PV.
>
>Did you change stuff in search to deal with pv with fail high/lows?
>
>In your code below, you're setting a move in the pv array, but that move is
>basically random:
>
> if (f < beta)
> greatest = f;
> else {
> int j;
> smallest = f; /* performs a cut-off */
> if (smallest >= greatest) {
> pv[ply][ply] = gen_dat[depth].m;
> for (j = ply + 1; j < pv_length[ply + 1]; ++j)
> pv[ply][j] = pv[ply + 1][j];
> pv_length[ply] = pv_length[ply + 1];
> }
> }
>
>gen_dat[depth].m is a generated move in the movelist, but it is not the
>bestmove. It isn't even the first move in the move list as depth is increased on
>every iteration.
I pulled the pm from the hash table, so the pv move is right (when it is there)
but the search still blows chunks of green goo:
pvs:
post
sd 99
st 99
go
Depth Eval Time Nodes PV
1 48 0 21 d2d4
2 0 0 84 d2d4 d7d5
3 35 40 797 d2d4 d7d5 b1c3
4 5 80 4313 e2e4 d7d5 f1b5 c8d7 b5d3
5 35 241 19619 e2e4 e7e5 d2d4 d7d5 g1f3
6 13 872 88472 e2e4 e7e5 d2d4 e5d4 d1d4 g8f6
7 30 4517 570969 e2e4 d7d5 e4d5 d8d5 d2d4 d5e4 g1e2 e7e5
8 18 30655 3279256 e2e4 b8c6 d2d4 e7e6 b1c3 d7d5 g1f3 g8f6
mtdf:
post
sd 99
st 99
go
Depth Eval Time Nodes PV
1 48 0 172
2 0 30 2224 d2d4
3 35 60 4602
4 5 451 41509 e2e4
5 35 1362 103001
6 13 7741 799578 e2e4
7 30 15553 1623933
move e2e4
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