Stockfish

[Homayoun]

Please pay attention :
Hi to all members
This thread only belongs to stockfish versions by its official developers If you want to share any versions from other authors , please create a separate thread for your content. Here we only want to monitor the SF devs changes by its developers between two official release intervals and monitor the engine development stages.
Thanks in advance

[Homayoun]

Author: cj5716
Date: Sun Apr 21 14:50:04 2024 +0200
Timestamp: 1713703804

Tweak TT aging and replacement strategies

We change the definition of "age" from "age of this position" to "age of this TT entry".
In this way, despite being on the same position, when we save into TT, we always prefer the new entry as compared to the old one.

Passed STC:
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 152256 W: 39597 L: 39110 D: 73549 Elo +1.11
Ptnml(0-2): 556, 17562, 39398, 18063, 549
https://tests.stockfishchess.org/tests/ ... e4cefbf215

Passed LTC:
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 51564 W: 13242 L: 12895 D: 25427 Elo +2.34
Ptnml(0-2): 24, 5464, 14463, 5803, 28
https://tests.stockfishchess.org/tests/ ... e4cefc153e

closes #5184

Bench 1479416

https://abrok.eu/stockfish/

[Homayoun]

Author: gab8192
Date: Wed Apr 24 18:38:20 2024 +0200
Timestamp: 1713976700

Implement accumulator refresh table

For each thread persist an accumulator cache for the network, where each
cache contains multiple entries for each of the possible king squares.
When the accumulator needs to be refreshed, the cached entry is used to more
efficiently update the accumulator, instead of rebuilding it from scratch.
This idea, was first described by Luecx (author of Koivisto) and
is commonly referred to as "Finny Tables".

When the accumulator needs to be refreshed, instead of filling it with
biases and adding every piece from scratch, we...

1. Take the `AccumulatorRefreshEntry` associated with the new king bucket
2. Calculate the features to activate and deactivate (from differences
between bitboards in the entry and bitboards of the actual position)
3. Apply the updates on the refresh entry
4. Copy the content of the refresh entry accumulator to the accumulator
we were refreshing
5. Copy the bitboards from the position to the refresh entry, to match
the newly updated accumulator

Results at STC:
https://tests.stockfishchess.org/tests/ ... e4cefc1386
(first version)
https://tests.stockfishchess.org/tests/ ... e4cefc6560
(final)

Non-Regression between first and final:
https://tests.stockfishchess.org/tests/ ... e4cefc660a

STC SMP:
https://tests.stockfishchess.org/tests/ ... e4cefc667c

closes https://github.com/official-stockfish/S ... /pull/5183

No functional change

[Homayoun]

Author: Stefan Geschwentner
Date: Sun Apr 28 21:46:45 2024 +0200
Timestamp: 1714333605

More reduction at cut nodes which are not a former PV node

But the tt move and first killer are excluded.

This idea is based on following LMR condition tuning
https://tests.stockfishchess.org/tests/ ... e4cefc0c71 by
using only the two largest terms P[0] and P[1].

Passed STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 173248 W: 45091 L: 44565 D: 83592 Elo +1.05
Ptnml(0-2): 693, 20534, 43673, 21002, 722
https://tests.stockfishchess.org/tests/ ... e4cefc7d37

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 722394 W: 183231 L: 181487 D: 357676 Elo +0.84
Ptnml(0-2): 462, 80650, 197252, 82348, 485
https://tests.stockfishchess.org/tests/ ... 253dcff7bf

closes https://github.com/official-stockfish/S ... /pull/5199

Bench: 1619613
https://abrok.eu/stockfish/