Winboard Forum

Me again asking about what I am facing programming my engine.
In this position:
r1bq4/1p4kp/3p1n2/p4pB1/2pQ4/8/1P4PP/4RRK1 w - - bm Re8
I am having a issue that I don't know if it is normal. I put my engine in two tests, one with Null-Move turned on and other with Null-Move turned off. The result is that no-null-move-version is retrieving the correct move faster than null-move-version. This sound strange to me, because the no-null-move-version take less time and less ply to reach the correct result.
does this sound normal to you?

Null Move version:

Code: Select all

ply score   time     nodes  pv
--- ----- ------ --------- -------------------------------------------------
 1    221      0       144  1. Qxc4
 2    178      0       306  1. Qxc4 Qb6+ 2. Rf2
 3    165      0      2130  1. Qxc4 Bd7 2. h4
 4    175      8     29060  1. Qxc4 Qb6+ 2. Rf2 Ne4 3. Be3
 5    158     16     53160  1. Qxc4 Qb6+ 2. Rf2 Ne4 3. Be3 Qb4
 5    184     87    291212  1. Rf3 Kf7 2. Qxc4+ Kg7 3. Bxf6+ Qxf6 4. Qd5 Qxb2 5. Qxd6
 6    281    109    365908  1. Rf3 Kf7 2. Qxc4+ d5 3. Bxf6 Qxf6 4. Qxd5+ Kg7 5. b3
 7    291    261    902833  1. Rf3 Kf7 2. Rfe3 d5 3. Re7+ Qxe7 4. Rxe7+ Kxe7 5. Qxf6+ Kd7 6. Qe5
 8    400   1203   3821874  1. Rf3 Kf7 2. Rfe3 d5 3. Re8 Qd6 4. Bxf6 b5
 8    865   2427   8243776  1. Re8 Qxe8 2. Qxf6+ Kg8 3. Bh6 Qe3+ 4. Bxe3 d5 5. Qd8+ Kf7 6. Qxd5+ Kf6 7. Qxc4

Version without Null Move

Code: Select all

ply score   time     nodes  pv
--- ----- ------ --------- -------------------------------------------------
 1    221      0       144  1. Qxc4
 2    178      0       320  1. Qxc4 Qb6+ 2. Rf2
 3    167      0      2105  1. Qxc4 Qb6+ 2. Rf2 Ne4
 4    175      7     27602  1. Qxc4 Qb6+ 2. Rf2 Ne4 3. Be3
 5    158     28     96093  1. Qxc4 Qb6+ 2. Rf2 Ne4 3. Be3 Qb4
 5    183    106    373719  1. Rf3 Kf7 2. Qxc4+ Kg6 3. Bxf6 Qxf6 4. Qd5 Qxb2 5. Qxd6+
 6    281    217    803202  1. Rf3 Kf7 2. Qxc4+ d5 3. Bxf6 Qxf6 4. Qxd5+ Kg7 5. b3
 6    423    815   2958933  1. Re8

Regards,
Fermin

What's your R? After 3..null, the mate will be missed if you're in quiescence.

Consider generating quiet checks in QS, especially in response to nullmove.

Teemu Pudas wrote:What's your R? After 3..null, the mate will be missed if you're in quiescence.

Consider generating quiet checks in QS, especially in response to nullmove.

Making tests, it seems that R is not the problem. Even your suggestion of generating quit checks in QS in response to nullmove does not work also. What I have modified is don't allow null move if current_depth <=2 and this show the expected move in ply 6 and 700.000 nodes, which is less than no-null-move version.

It's normal.
The null move search is a boolean function that tells you if your opponent has a threat.
You cut the branch when there is none. You cut the branch but that branch could lead to a better variation than what you'll get in other branch.
You just can't know because :
1) you passed your turn so you did not play the most threatening move
2) you searched with a lower depth so you missed some tactics
3) your lower search depth lead you in quiescent search while the good move is perhaps not a capture.

HJ.