Please say me where I´m wrong.
I understood that perft results are the number of leaf nodes (nodes that do not have more nodes beyond it, at least with perft number limit).
But I believe I found a position where at least Gaviota and Satana (the only engines I understand how to use to calculate perft) give me a result that is not the same I found "by hand".
This is the position:
7k/4R1pp/8/8/8/8/8/7K w - - 0 1
Perft 2 gives me 73 in both engines (and in mine I´m working in) that is the number of leaf nodes without count the position after Re8++ that is, as far as I understood, a leaf node too.
Thanks!
Perft, leaf nodes?
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Re: Perft, leaf nodes?
SOLVED!
Here is the correct definition of Perft:
Here is the correct definition of Perft:
Aleks Peshkov wrote:Perft is recursive number of legal moves.
Perft for depth 1 is number of legal moves from the given position.
Perft for depth N is sum of legal moves for all positions of Perft N-1.
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Re: Perft, leaf nodes?
You can use for example Stockfish or Andscacs to calculate perft, too.
Just put
position fen 7k/4R1pp/8/8/8/8/8/7K w - - 0 1
and then
perft 2
Just put
position fen 7k/4R1pp/8/8/8/8/8/7K w - - 0 1
and then
perft 2
Daniel José - http://www.andscacs.com
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Re: Perft, leaf nodes?
Hello Luis:
Just to complete my post:
I hope no typos.
Regards from Spain.
Ajedrecista.
Here is, in fact, how JetChess perft counter reports perft(2) of that position:Luis Babboni wrote:SOLVED!
Here is the correct definition of Perft:
Aleks Peshkov wrote:Perft is recursive number of legal moves.
Perft for depth 1 is number of legal moves from the given position.
Perft for depth N is sum of legal moves for all positions of Perft N-1.
Code: Select all
1 Re7-e8 0
2 Re7-f7 5
3 Re7*g7 3
4 Re7-d7 5
5 Re7-c7 5
6 Re7-b7 5
7 Re7-a7 5
8 Re7-e6 5
9 Re7-e5 5
10 Re7-e4 5
11 Re7-e3 5
12 Re7-e2 5
13 Re7-e1 5
14 Kh1-g1 5
15 Kh1-g2 5
16 Kh1-h2 5
Total: 73
Code: Select all
perft(1) = 16
perft(2) = 73
perft(3) = 1,241
perft(4) = 5,861
perft(5) = 101,487
perft(6) = 539,658
perft(7) = 9,389,471
perft(8) = 55,628,133
perft(9) = 970,934,310
perft(10) = 6,203,290,408
perft(11) = 108,581,645,499
perft(12) = 731,006,640,533
perft(13) = 12,821,244,003,733
perft(14) = 89,335,944,621,556
perft(15) = 1,568,592,660,477,175
perft(16) = 11,198,005,325,037,030
perft(17) = 196,680,381,198,782,558
perft(18) = 1,431,536,409,060,656,547
Regards from Spain.
Ajedrecista.
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Re: Perft, leaf nodes?
Thanks Daniel, I knew just "setboard" command!cdani wrote:You can use for example Stockfish or Andscacs to calculate perft, too.
Just put
position fen 7k/4R1pp/8/8/8/8/8/7K w - - 0 1
and then
perft 2
Thanks Jesús!
Yes, I was wrong in the definition of perft.
If there is no ties or checkmates before the number in perft command, both are the same but was not the case.
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Re: Perft, leaf nodes?
You can also use zurichess, too: https://godoc.org/bitbucket.org/zurichess/tools/perft
Code: Select all
$ ./perft --fen "7k/4R1pp/8/8/8/8/8/7K w - - 0 1" --max_depth 10
Searching FEN "7k/4R1pp/8/8/8/8/8/7K w - - 0 1"
depth nodes captures enpassant castles promotions eval KNps elapsed
-----+------------+----------+---------+---------+----------+-----+------+-------
1 16 1 0 0 0 1722 9.289µs
2 73 1 0 0 0 1808 40.381µs
3 1241 44 0 0 0 5345 232.173µs
4 5861 99 0 0 0 4758 1.2319ms
5 101487 2192 0 0 0 17750 5.717569ms
6 539658 9138 0 0 0 36895 14.627033ms
7 9389471 176283 0 0 0 194111 48.371719ms
8 55628133 886521 0 0 0 341662 162.816227ms
9 970934310 18175344 0 0 0 722655 1.343566224s
10 6203290408 92877449 0 0 1106664 493569 12.568227604s
zurichess - http://www.zurichess.xyz