It seems we have a lot of totally useless code !
After 8577 games 1504 - 1451 - 5622 ELO +2 (+- 4.4)
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Add blunder cabability to skill level feature.
The idea is that instead of choosing the best move at the end
of the ID loop, we now do this at a randomly chosen sampling depth
dependent on SkillLevel, so that at low skill levels we sample when
ID loop has reached only a small depth and so we have an higher
probability to pick up a blunder.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
The idea is to try a shallow search with reduced beta
on bad captures so to quickly prune them out in case
are really bad.
After 5529 games 966 - 868 - 3695 ELO +6 (+- 5.4) LOS 91%
Tested also version without upper limitation to 8 plies:
After 8780 games 1537 - 1398 - 5850 ELO +5 (+- 4.3) LOS 93%
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Rescaled Skill level from 0 to 20. At level 19 is still
comparable with Crafty 20.14, while at low levels strength
increase is now less steep.
Thanks to Joona and Heinz for testing and valuable
comments.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
It is now possible to adjust skill level of Stockfish
from 10 (full strength) to 0.
Skill adjustment is done in such a way that is CPU speed and
time control largely independent, at least at low skills. It
means that given a skill we have same play level on a mobile
phone and on a super OCTAL CPU, at 1' per game or at 180'.
At skill 9 strength is that of an average engine, I have used
Crafty 20.14 to tune and we are more or less there. At skill 0
engine is pretty weak but still shows a realistic play.
When skill is not used we don't have any impact on the regular
code.
Idea to use MultiPV is from Heinz van Saanen, implementation and
formulas by me.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This is how Shredder, Rybka and others do and
avoids user is confused by a fail high (sent to GUI)
followed by a fail low (not sent).
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Has been reported by Justin Blanchard that
this creates problems on some buggy GUI.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Fix a corner case where we start aspiration window and
suddendly we get a VALUE_KNOWN_WIN / MATE score, this makes
aspiration to blow up in a series of researches loops.
Exit aspiration loop in that case.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Use first iteration to get a proper startup score
and possibly detect an easy move.
After 5180 games:
Mod vs Orig 847 - 823 - 3510 ELO +1 (+- 5.5)
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Because we are never in check there and evaluation cannot
return a mated value the condition is useless.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Now that we don't have anymore a search stack array in
SplitPoint we can rename this data member to somthing more
usual.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Use a local variable instead. To make it work we need to
correctly init next ply search stack at the beginning of the
search because now that ss is allocated on the stack instead
of on the global storage it contains garbage.
As a side effect we can peform a fast search stack
init in id_loop().
With this patch size of SplitPoint goes from 71944 to 136 bytes,
and consequently size of Thread goes from 575568 to 1104 bytes.
Finally the size of ThreadsManager that contains all the thread
info goes from 9209248 to just 17824 bytes !!
No functional change also in faked split.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This allow us to restore the old depth 12 benchmark
and fixes one and for all the depth mess.
Test confirms no regression:
After 5658 games 892 - 924 - 3842 ELO -1 (+- 5.2)
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Note that this introduces an asymmetry in which best move
is searched deeper then others also in MultiPV, but this is
not an error per se.
No functional change when MultiPV = 1
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Skip writing fail high/low sequences. Note that we don't need
fail high/low markers anymore in pretty_pv().
No functional change but some do/undo move sequences.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
First search should be done at iteration = 1, not 2. So offset
the variable by one.
As a nice side effect now search correctly stops at PLY_MAX
included, not after searching (PLY_MAX - 1) as before.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Interestingly this patch will make people complain search depth
is reduced against 2.0.1 ;-) but actually it is only an artifact.
Spotted by Joona.
No functional change apart from a different do / undo move
sequence due to teh fact that we don't call pv_info_to_uci()
anymore before entering id loop.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
No functional change apart form move reordering because
pv_info_to_uci() performs a do / undo_move sequence.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Biggest advantage is be able to analize positions
without "loss of memory" when goind back/forth in
a position.
Patch has proven to fix analysys problems and is even
worths some elo points.
After 5811 games Mod- Orig:
1037 - 902 - 3872 +8 ELO (+- 3.6) LOS 97%
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This let us get rid of number_of_evasions()
After 5487 games
Mod- Orig: 851 - 852 - 3784 +0 ELO (+- 3.7)
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Move qsearch scoring functionality out of RootMoveList
initialization. Will be needed by future patches.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This is used for secondary scoring so it does not
changes the fact that Rml[0].pv[0] is always tried
as first anyhow.
It happens this is even a no functional change patch
becuase we reinsert PV in TT after a search so that
TT move is actually Rml[0].pv[0].
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
So to better spot where the differences really
count. Also add some more additional cleanup.
Harmless functional change and no regression.
After 5780 games
Mod- Orig: 931 - 955 - 3894 ELO -1 (+- 3.6)
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
In case of a Root node we can leave with bestValue set
to -VALUE_INFINITE if search is stopped by the GUI and
stopReques flag is raised.
This patch fixes the issue.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
