PeSTO: Piece Square Tables Only

Right now PeSTO is participating in the Qualification League of TCEC S17. PeSTO is an “experimental” chess engine in that it has only minimal chess knowledge in it’s evaluation and that it depends on the AB search as much as possible as opposed to the recent development of Neural Network engines which rely foremost on complex learned chess knowledge.

The most elementary chess knowledge is the relative value of the chess pieces. Playing with only that knowledge is (still?) not enough to let PeSTO play reasonably good chess, although it performs very good in tactical testsuites like WAC. It also needs some elementary positional knowledge to play reasonable chess. The simplest form of positional knowledge are Piece Square Tables (PST), in which a value is assigned to every square on the board for every piece. A higher value for the square means a general better position for that piece.

The values change during the course of the game. In the beginning of the game it’s better for the king to stay on his own border of the board, in the endgame the king should be away from it’s own border. That’s why there are 2 PST for each piece, one for the opening and one for the endgame. Depending on how many pieces are left on the board the values between opening and endgame are interpolated accordingly (so called tapered evaluation). In addition to the piece values and PST there is a tempo bonus for the side to move, and that’s it, no other chess knowledge is present in PeSTO.

PeSTO uses different tables than rofChade and also has some search tweaks (most important less aggressive LMR due to worse move ordering). The tables are tuned with the Texel tuning method.

If you want to use PeSTO, you can download it in the download section.

TCEC Season 14, Div3 sixth place

During the Div4 tournament I had been experimenting with the search part of rofChade together with the added evaluation terms. Version 1.0 only had material and Piece Square Tables for evaluation, but with the added evaluation elements it seems that LMR reductions can be a more aggressive than without the eval terms. Probably the move sorting of the quiet moves becomes a bit more accurate with more eval.

The version with more aggressive LMR seemed a bit better and I had also been playing with the usage of the hash table in quiescence search. Because the TCEC tournament runs on a dual processor machine with 44 physical cores,  I thought that not using the hashtable in quiescence might be better. Testing on my Threadripper 1950X showed some elo gain.

So eventually I decided to play with the new version in Div3. In Div3 the new version performed fairly good. Not using the hashtable in quiescence made the NPS go up from 58M to around 73M in the opening phase, but with lazy SMP more NPS not necessarily means better. Eventually it lost too much games in the last round and ended sixth place. Lc0 and Komodo MCTC ended first and second and where too strong for the rest of the Division(also for Div2 in which they also finished first and second).

The difference between places 3 to 6 was just 0.5 point, and because rofChade crashed one time in a dead draw endgame against Arasan and the TCEC tiebreak rules it ended up sixth.

Fortunately I was able to find the bug that caused the crash, so that crash won’t happen again in the future.  

Sixth place ensured a stay in Div3 for the next season, so hopefully rofChade will do even better then!

TCEC Season 14, Div4 second place

Thanks to the great work of Graham Banks rofChade was able to participate in the TCEC Season 14 tournament. There was a small problem however, I was still in the middle of playing, testing and tuning of rofChade for the upcoming CSVN tournament, so there was not a rofChade version available and the expected start of  TCEC season 14 was the next days.

So overnight a tuning run was started, and after some testing of that version, it was send to the TCEC organisation. Turned out, it was just minutes before the start…. When I looked  at the TCEC site just minutes after sending the version to see when the tournament would start, it was already playing some games in the testrun!  

During the tournament rofChade played very good and ended second place, behind the Komodo MCTC version. It even managed to win one game from Komodo with an original checkmate on the board, which is a rare occasion at TCEC because of the adjudication rules.

Second place means promotion to Div3!

Rofchade split 1st place at 12th ACCA World Computer Rapid Chess Championships

On  October 20/21 2018 rofChade participated at the 12th ACCA World Computer Rapid Chess Championships, and finished 1st together with Komodo and Chiron. After 2 tie breaks, Komodo won the tournament, while rofChade finished 3th.

The participating rofChade version was a preliminary version with first experimental evaluation elements.

This great result was not without luck. The game against Erdo ended in an easy win because of a GUI problem of Erdo. 

The game against Komodo seemed to end in a draw (which would have been great already…) but suddenly Komodo lost because of an internet problem.

Automato 
 icctd version: 8.1192 (Compiled Jul 28 2018 15:03:58)
 # 2262   The 2018 Twelfth Annual World Computer Rapid Chess Championships Round Robin Standard 25 4 unrated manager 
 ******   12 players/11 round (of 11)
          Managed by .   (Sat Oct 20 18  8:42 - Sun Oct 21 18 12:18)
          System: main TD: Automato
          max_bye_points:1000
          max_best:3000 last_sort:score scheduled: no
     Name                   1  2  3  4  5  6  7  8  9 10 11 12 Score  #g
   1 rofchade       (2762)  xx 1  1  =  =  1  1  =  =  =  1  1   8.5  11
   2 ChironX        (2784)  0  xx =  1  =  =  1  1  1  1  1  1   8.5  11
   3 Komodo         (3392)  0  =  xx 1  1  =  1  =  1  1  1  1   8.5  11
   4 BertaX         (2321)  =  0  0  xx 1  =  1  1  1  1  1  1   8.0  11
   5 ArasanX        (2437)  =  =  0  0  xx =  =  =  1  1  1  1   6.5  11
   6 Erdo           (2861)  0  =  =  =  =  xx 0  1  1  =  1  1   6.5  11
   7 WaspX          (2930)  0  0  0  0  =  1  xx 1  =  1  1  1   6.0  11
   8 NightmareX     (2712)  =  0  =  0  =  0  0  xx 1  1  =  1   5.0  11
   9 MarvinX        (2792)  =  0  0  0  0  0  =  0  xx =  1  =   3.0  11
  10 Goldbar        (2499)  =  0  0  0  0  =  0  0  =  xx 0  1   2.5  11
  11 TheBaron       (2606)  0  0  0  0  0  0  0  =  0  1  xx 1   2.5  11
  12 Telepath       (2285)  0  0  0  0  0  0  0  0  =  0  0  xx  0.5  11 

Thus, we have a 3 way tie for first. The first tie breaker is a double round robin G/10+1. The second tie breaker is a round robin G/3+1.

  
Automato 
 icctd version: 8.1192 (Compiled Jul 28 2018 15:03:58)
 # 2264   The 2018 Twelfth Annual World Computer Rapid Chess Championships Final Manual Blitz 10 1 unrated manager 
 ******   3 players/9 round (of 9)
          Managed by .   (Sun Oct 21 18 13:50 - Sun Oct 21 18 15:58)
          System: main TD: Automato
          max_bye_points:1000
          max_best:3000 last_sort:score scheduled: no
     Name                  R1    R2    R3    R4    R5    R6    R7    R8    R9    Score  #g
   1 Komodo         (3392) =w2   bye   =b3   =b2   bye   +w3   +w2   bye   =b3     4.0   9
   2 ChironX        (2805) =b1   =b3   bye   =w1   =w3   bye   -b1   +b3   bye     3.0   9
   3 rofchade       (2762) bye   =w2   =w1   bye   =b2   -b1   bye   -w2   =w1     2.0   9
 

Rofchade finished 5th in the monthly HGM tournament of august 2018

Yesterday rofchade participated in the monthly HGM tournament and finished 5th after 9 rounds. A very nice result!. The results of the tournament are:

 

Name Rating Score Perform Upset Result
1 +LeelaZero [1971] 13.0 [2234] [182] +16w +12w +04b +07b +06w =02b =03b +11w +08w
2 -Berta [1991] 11.5 [2080] [56] =13w +05b =06w +12w +14b =01w =08b =03w +11b
3 +WaspX [2002] 11.0 [2031] [49] =04w =08b +13w +14w =05b +07b =01w =02b =06b
4 -Schooner [1762] 11.0 [2049] [826] =03b +15w -01w =11b +10w =06b +07w =05w +12b
5 +RofChade [1729] 10.5 [1980] [790] =11b -02w +27w +10b =03w +12b =06w =04b =07w
6 +ArasanX [2093] 10.0 [1926] [0] +15w +09w =02b =08w -01b =04w =05b =12b =03w
7 +NightmareX [2006] 10.0 [1892] [0] +10w +14w +11b -01w =08b -03w -04b +21w =05b
8 +rpiStockfish [1911] 10.0 [1980] [223] +20w =03w +09b =06b =07w -11b =02w +14w -01b
9 +Goldbar [1899] 10.0 [1874] [28] +21w -06b -08w =20b +15b =14w =11w =10b +16w
10 +Marvin [1814] 10.0 [1784] [42] -07b =13b +16w -05w -04b +20w +17b =09w +18b
11 +WaDuuttie [1956] 9.5 [1841] [0] =05w +27b -07w =04w +13b +08w =09b -01b -02w
12 -Arminius [1849] 9.5 [1805] [122] +17w -01b +21w -02b +16b -05w +13b =06w -04w
13 +Pirarucu [1754] 9.5 [1793] [202] =02b =10w -03b +17w -11w +22b -12w +24b =14w
14 +Baron [1863] 9.0 [1802] [18] +33w -07b +20w -03b -02w =09b +15w -08b =13b
15 -Tornado [1823] 9.0 [1670] [0] -06b -04b +22w +21b -09w +17w -14b -18w +25w
16 -Tinker [1744] 9.0 [1661] [0] -01b +17w -10b +18b -12w +24w -21b +22w -09b
17 +rpiArminius [1583] 9.0 [1638] [39] -12b -16b +25w -13b +18w -15b -10w +28b +21w
18 -Jumbo [1537] 9.0 [1680] [461] -24w +29b +33b -16w -17b +27w +20b +15b -10w
19 -RookieMonster [1445] 9.0 [1647] [459] -29w +28b +23w =25b =30b +33w =22b =20w +24w
20 -tomitankChess [1645] 8.5 [1569] [127] -08b +24w -14b =09w =21w -10b -18w =19b +31w
21 +atomBaron [1622] 8.5 [1643] [133] -09b +33w -12b -15w =20b +29w +16w -07b -17b
22 -Nameless [1564] 8.5 [1529] [25] -27w +25b -15b =24w +33b -13w =19w -16b +32b
23 -Isa [1408] 8.5 [1480] [197] =30b +32w -19b -29b =26w +38w +37b +34w +33b
24 +rpiMinkoChess [1515] 8.0 [1532] [83] +18b -20b =29w =22b +27w -16b +28w -13w -19b
25 +Bliep [1507] 8.0 [1529] [127] +28b -22w -17b =19w -31b +34w +27b +33w -15b
26 +Embla [1293] 8.0 [1355] [130] -32w =36b +35b +37w =23b =30w +39b +38w +40w
27 +Floyd [1552] 7.5 [1389] [12] +22b -11w -05b -33w -24b -18b -25w +39w +35b
28 +Spartacus [1500] 7.5 [1376] [0] -25w -19w +34b +30w -29b +31w -24b -17w +36b
29 +rpiFruit [1455] 7.5 [1453] [75] +19b -18w =24b +23w +28w -21b -33b -32w +37b
30 +Joker [1440] 7.5 [1314] [2] =23w +34w =31b -28b =19w =26b -32w +40b +38w
31 +CTdccc [1317] 7.5 [1449] [251] -34b +35w =30w +32b +25w -28b +36w +37w -20b
32 -Weini [1236] 7.5 [1417] [480] +26b -23b +36w -31w +40b +39w +30b +29b -22w
33 -Nemeton [1589] 7.0 [1328] [0] -14b -21b -18w +27b -22w -19b +29w -25b -23w
34 +KingSlayer [1390] 7.0 [1302] [0] +31w -30b -28w +38w +35b -25b +40w -23b +39b
35 -Skiull [1157] 5.0 [1168] [71] +37b -31b -26w +39b -34w +40w +38b -36w -27w
36 +rpiEmbla [1139] 5.0 [1191] [109] +39b =26w -32b +40w +38b -37w -31b +35b -28w
37 +microMax [1228] 4.0 [1062] [0] -35w -38w +40b -26b +39w +36b -23w -31b -29w
38 +rpiBikjump [1051] 3.0 [1088] [279] +40w +37b +39w -34b -36w -23b -35w -26b -30b
39 +GearHeart [1153] 1.5 [893] [893] -36w +40b -38b -35w -37b -32b -26w -27b -34w
40 +POS [791] 0.0 [831] [0] -38b -39w -37w -36b -32w -35b -34b -30w -26b

53th CSVN Programmer tournament in Leiden

On 2 and 3 June 2018 a preliminary version of Rofchade participated in the 53th CSVN Programmer Tournament in Leiden. It was the first real tournament for Rofchade and for me as well, and after 2 days of hard processing Rofchade ended 3th together with chess22k. A very nice result which tastes like more !

The final ranking is as follows:

No.  PNo.  Name                       Score WP    SB
---------------------------------------------------------
 1.     7  Hiarcs                      9.0  36.0  36.00  
 2.     2  The Baron                   7.0  38.0  22.50
 3.     6  chess22k                    6.5  38.5  20.25
       10  Rofchade                    6.5  38.5  20.25
 5.     8  Arminius                    5.0  40.0  11.75
        9  The King                    5.0  40.0  11.75
 7.     3  RedQueen                    3.0  42.0   3.00
 8.     4  Spartacus                   2.0  43.0   1.00
 9.     5  Embla                       1.0  44.0   0.00
 10.    1  Gadget                      0.0  45.0   0.00

Further info and games can be found on the CSVN website.