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Transposition Table #76

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@phuang1024 phuang1024 commented Apr 21, 2021 •
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Describe changes

Lookup eval if transposition table entry is greater than current search depth.
Also added hash verification with popcnt and modulo.

Testing info

140 ELO worse than v1.0.0 as of e327991

phuang1024 and others added 30 commits April 14, 2021 15:24
@phuang1024
Break from search if transposition already found.
4efaa49 
Gets to depth 34 in 8/k7/3p4/p2P1p2/P2P1P2/8/8/K7 w - - 0 1.
@phuang1024
Lowered hash factor.
00162b2 
Now 130500 entries per megabyte.
@phuang1024
Removed clear hash.
68d53d9 
Automatically clears in set_hash.
@phuang1024
Return 1 node in lookup.
7e221cb
@phuang1024
Removed clear hash every search.
a29f5f9
@phuang1024
Added HashClearThres option.
78691f3 
Clear hash table when HashClearThres percent full.
@phuang1024
Added TableLookupThres option.
ee6604f 
Threshold to start looking up eval.
@phuang1024
Always clear hash when looking up.
1feb45f 
A hash collision in getting eval is worse than getting the best move.
@phuang1024
Added options in setoption.
7458f73
@phuang1024
Changed lookup threshold to 0 in bench.
766234e
@phuang1024
Fixed mate score print bug.
7255dd3 
Bench: 766039
@phuang1024
Added transposition modulo.
24a3d22 
Number to ensure two positions are the same.
Bench: 766039
@phuang1024
Store hash instead of mod.
41ec43c 
Bench: 766039
@phuang1024
Only check for move equality if not matched.
0051f1b 
Reduces total checks.
Bench: 766039
@phuang1024
Improved transposition table.
41e64f8 
Always lookup and removed options.
@phuang1024
Only write to hash table if full search.
bfc8348
@phuang1024
Don't return lookup if root.
20b4890
@phuang1024
Added endgame draws.
054a021 
If position has popcnt of draw pieces, return 0 in eval.
@phuang1024
Added parts at top of while loop.
83d9baa
@ArjunSahlot
Remove K column and add KNNvK draws.
8b28afe
@phuang1024
Removed KNN draw.
f937e7f 
Under certain conditions checkmate still possible.
Tablebases needed to decide which.
@phuang1024
Merge pull request #69 from megalodon-chess/endgame
ab46cb3 
Endgame
@ArjunSahlot
Bug fixes.
ed6026b
@ArjunSahlot
Optimize array comparison.
37a1d95
@ArjunSahlot
Formatting.
5f98738
@phuang1024
Merge pull request #70 from megalodon-chess/arjun-patch-4
76730ab 
Arjun Patch 4
@phuang1024
Fixed bench.
9427a04 
Need to initialize before benching.
Moved bench to uci loop.
Bench: 156869
@phuang1024
Use 255 sets of bits.
68c44d7 
Less collisions than 101.
@ArjunSahlot
Add sets for all zobrist parts.
c11b3cc
@ArjunSahlot
Fix type bugs and optimizations.
231fd29
@phuang1024 phuang1024 added enhancement New feature or request search Search related labels Apr 21, 2021
@phuang1024 phuang1024 added this to the Transposition Table milestone Apr 21, 2021
@phuang1024 phuang1024 requested a review from ArjunSahlot April 21, 2021 22:52
phuang1024 and others added 4 commits April 21, 2021 15:53
@phuang1024
Merge branch 'main' into search
f8ed5f5
@ArjunSahlot
Merge branch 'main' into search
2dbe52f
@phuang1024
Store whole position in transposition for verify.
6270187 
No more hash collisions.
Bench: 156987
@phuang1024
Commented pawn structure and pawn attacks.
ac32ccd 
Those were slow and didn't add much to the eval.
New NPS is about 700-800K
Bench: 284399
phuang1024 and others added 14 commits April 22, 2021 16:02
@phuang1024
Merge branch 'main' into search
9dcac67
Fixed compiler warnings.
28a574c 
Char subscripts and unused variables.
Bench: 284399
@phuang1024
Only write to hash table if depth >= 2.
dd00e5a 
Decreases total writes, which decreases overwrites of important entries.
Bench: 401931
Increment mate score every depth instead of deciding at leaf.
e327991 
Improves accuracy on lookups.
@phuang1024
Formatting.
6c4c3de 
Align == and &&.
Bench: 401899
@ArjunSahlot
Merge branch 'main' into search
a9daff5
@phuang1024
Set as no match if entry depth is 0.
8cbc5ff 
If entry was not previously written, don't read from it.
Bench: 401899
@phuang1024
Removed unused arguments from SearchInfo constructor.
327936f 
NPS, time, and hashfull were always set to 0. No point using them.
Bench: 401899
@phuang1024
Only return entry if real depth >= depth.
b5b17ab 
Used to have an unbalanced search.
I.e., some nodes were much deeper than others due to lookup, which resulted in playing mistakes.
Bench: 401899
@phuang1024
Renamed function: pinned -> pin_mask
b19c307 
Bench: 401899 (no functional change)
@phuang1024
Added overload of legal_moves which computes o_attacks internally.
0a1016b 
Bench: 401899 (no functional change)
@phuang1024
Revert b5b17ab.
3f071a3 
Did not improve strength.
Bench: 401899
@phuang1024
Receive time limit from stdin in daily puzzle.
929ef11 
No functional change.
@phuang1024
Added ClearHash option.
da286e9 
Clears hash table.
Bench: 401899
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