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The Prophet and The Gibbon

Graham Banks recently ran a blitz tournament (40 moves/16 minutes) he titled ‘The Prophet and The Gibbon’ between 16 engines, including Prophet 4.2.

Final Standings

21.5 – Prophet 4.2 64-bit
21.0 – SoFCheck 0.9.1-beta 64-bit
18.0 – Gibbon 2.69a 64-bit
18.0 – Isa 2.0.83 64-bit
17.0 – Queen 4.03
16.5 – Fornax 3.0 64-bit
16.5 – Barbarossa 0.6.0 64-bit
14.5 – Horizon 4.4
13.0 – Jazz 840 64-bit
13.0 – Sage 3.53
13.0 – EveAnn 1.72
13.0 – CeeChess 1.3.2 64-bit
12.5 – Napoleon 1.8 64-bit
12.0 – StockNemo 3.0.0.2 64-bit
11.0 – FireFly 2.7.2 64-bit
9.5 – Ares GB 1.1 64-bit

Woo hoo!


The complete tournament pgn (zipped) can be downloaded here:
http://kirill-kryukov.com/chess/discuss … p?id=51143

Passed pawns and Non-linear Mobility

Since I released Prophet 4.2 I’ve made a couple of additional evaluation changes:

  1. The passed pawn bonus has been made more granular. Where it used to be a simple bonus for a passed pawn, now it varies depending on the pawn’s rank. 40,000 bullet games says that change was worth about 14 ELO.
  2. Bishop and queen mobility has been made non-linear. This change was inspired by Erik Madsen’s MadChess blog – https://www.madchess.net/2014/12/16/madchess-2-0-beta-build-29-piece-mobility/ . The idea is to encourage piece development. I had originally plugged Erik’s values in verbatim, but they didn’t mesh well with existing weights and testing showed it weakened the program. After running the auto-tuner, this change brought in an additional 22 ELO.

In my first attempt at running the auto-tuner, I just started with the previously tuned weights, plus Erik’s values for bishop and queen mobility, but the tuner couldn’t seem to find any improvements. The error bounced around a little, going up and down, and not making any progress. I eventually decided to do a complete reset. I set the piece values to the traditional 1/3/3/5/9 values, and everything else to 0. Then I re-tuned and validated with some bullet games. The learning curve:

Fresh off the heals of these improvements, Prophet played in an informal online engine blitz tourney today. Unfortunately it was a pretty rough outing, placing just 16/20 with 2.5 points out of 9. It was a very strong field though. Even the 10th place finisher is nearly 3000 ELO on CCRL’s 40/2 list.

:Tourney Players: Round 9 of 9 
:
:     Name              Rating Score Perfrm Upset  Results 
:     ----------------- ------ ----- ------ ------ ------- 
:  1 +LczTinker         [2971]  6.5  [2937] [   0] +07w =05w =06b =03b +02w =04b =09w +11w +12b 
:  2 +NightmareX        [2909]  6.5  [2939] [   0] +12w =06w +09b =04w -01b =05w +07b +08w +11b 
:  3 +ChessSystemTalX   [2900]  6.5  [2898] [  35] +10w +09w =08b =01w =06b +07w =05b =04w +13b 
:  4 +RubiChess         [2875]  6.5  [2947] [  77] +13w +11w =05b =02b +08w =01w =06b =03b +09w 
:  5 +ArasanX           [2859]  6.0  [2836] [ 110] +14w =01b =04w =08b +12w =02b =03w =09b +16w 
:  6 +WaspX             [2830]  6.0  [2679] [ 181] +15w =02b =01w +17b =03w =08b =04w +13w =10b 
:  7 +TheBaron          [2569]  5.5  [2457] [   3] -01b +14w +16w =11b +17w -03b -02w +18b +15b 
:  8 +Goldbar           [2861]  5.0  [2533] [  19] +16w +17b =03w =05w -04b =06w =13b -02b +18w
:  9 +Marvin            [2752]  5.0  [2683] [ 162] +18w -03b -02w +16b +11w +12b =01b =05w -04b 
: 10 +Nalwald           [2500]  5.0  [2325] [ 165] -03b +18w =15b -12b -13w +17b +16w +14b =06w 
: 11 +atomGoldbar       [2575]  4.5  [2480] [   0] +20w -04b +13w =07w -09b +16b +14w -01b -02w 
: 12 +WaDuuttie         [2567]  4.5  [2411] [   0] -02b +15w =14b +10w -05b -09w +18b +17w -01w 
: 13 +rpiArminius       [2272]  4.0  [2425] [ 522] -04b +20w -11b =14w +10b +15w =08w -06b -03w 
: 14 +atomFloyd         [2242]  4.0  [2267] [ 177] -05b -07b =12w =13b +15w +18w -11b -10w +17b 
: 15 +Skiull            [1966]  3.0  [2170] [ 410] -06b -12b =10w +18w -14b -13b +17w =16b -07w 
: 16 -Prophet           [2253]  2.5  [2325] [ 351] -08b +19w -07b -09w +18b -11w -10b =15w -05b
: 17 -Skipper           [1662]  2.0  [2219] [1120] +19b -08w +18b -06w -07b -10w -15b -12b -14w 
: 18 +atomSargon        [1840]  0.0  [1974] [   0] -09b -10b -17w -15b -16w -14b -12w -07w -08b 
: 19 +atomNightmare     [forf]  0.0  [1557] [   0] -17w -16b 
: 20 +POS               [forf]  0.0  [2023] [   0] -11b -13b 
:
:     Average Rating    2474.2 

Next up- I’m going to continue with the mobility theme a little longer by testing rook mobility, then knight outposts, trapped bishops, and connected rooks on open files. I don’t expect any of those will be big points by themselves but cumulatively they might be worth a bit.