{"action":"created","issue":{"url":"https://api.github.com/repos/official-stockfish/Stockfish/issues/216","labels_url":"https://api.github.com/repos/official-stockfish/Stockfish/issues/216/labels{/name}","comments_url":"https://api.github.com/repos/official-stockfish/Stockfish/issues/216/comments","events_url":"https://api.github.com/repos/official-stockfish/Stockfish/issues/216/events","html_url":"https://github.com/official-stockfish/Stockfish/pull/216","id":54671383,"number":216,"title":"Better PV on fail high/low","user":{"login":"glinscott","id":554932,"avatar_url":"https://avatars.githubusercontent.com/u/554932?v=3","gravatar_id":"","url":"https://api.github.com/users/glinscott","html_url":"https://github.com/glinscott","followers_url":"https://api.github.com/users/glinscott/followers","following_url":"https://api.github.com/users/glinscott/following{/other_user}","gists_url":"https://api.github.com/users/glinscott/gists{/gist_id}","starred_url":"https://api.github.com/users/glinscott/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/glinscott/subscriptions","organizations_url":"https://api.github.com/users/glinscott/orgs","repos_url":"https://api.github.com/users/glinscott/repos","events_url":"https://api.github.com/users/glinscott/events{/privacy}","received_events_url":"https://api.github.com/users/glinscott/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":5,"created_at":"2015-01-17T19:01:31Z","updated_at":"2015-01-17T23:06:28Z","closed_at":null,"pull_request":{"url":"https://api.github.com/repos/official-stockfish/Stockfish/pulls/216","html_url":"https://github.com/official-stockfish/Stockfish/pull/216","diff_url":"https://github.com/official-stockfish/Stockfish/pull/216.diff","patch_url":"https://github.com/official-stockfish/Stockfish/pull/216.patch"},"body":"This is something that would be nice to fix before SF 6 ships.  The patch as written is a non-functional change.\r\n\r\nThe goal is retain a long PV on fail high/low as well (just the PV from the last iteration before it failed high/low), if the new short PV matches the beginning.  In practice, this seems to work quite well.\r\n\r\nHere is an example search from the root position, showing some fail high/lows with long PVs:\r\n```\r\ninfo depth 1 seldepth 1 multipv 1 score cp 62 nodes 5 nps 1666 tbhits 0 time 3 pv d2d3\r\ninfo depth 2 seldepth 2 multipv 1 score cp 67 nodes 24 nps 6000 tbhits 0 time 4 pv e2e3 b7b6\r\ninfo depth 3 seldepth 3 multipv 1 score cp 56 nodes 109 nps 27250 tbhits 0 time 4 pv d2d4 d7d6 e2e3\r\ninfo depth 4 seldepth 4 multipv 1 score cp 58 nodes 302 nps 60400 tbhits 0 time 5 pv b1c3 e7e6 e2e3 b7b6\r\ninfo depth 5 seldepth 5 multipv 1 score cp 101 nodes 743 nps 148600 tbhits 0 time 5 pv b1c3 e7e6 e2e3 b7b6 d2d4\r\ninfo depth 6 seldepth 6 multipv 1 score cp 8 nodes 5036 nps 559555 tbhits 0 time 9 pv e2e4 b8c6 d2d4 d7d5 e4e5 e7e6\r\ninfo depth 7 seldepth 8 multipv 1 score cp 43 nodes 7048 nps 704800 tbhits 0 time 10 pv e2e4 d7d5 e4e5 d5d4 g1f3 b8c6 d2d3\r\ninfo depth 8 seldepth 8 multipv 1 score cp 10 nodes 12147 nps 934384 tbhits 0 time 13 pv e2e4 d7d5 e4e5 d5d4 g1f3 b8c6 d2d3 e7e6\r\ninfo depth 9 seldepth 11 multipv 1 score cp 44 nodes 19236 nps 1131529 tbhits 0 time 17 pv e2e4 d7d5 e4d5 d8d5 b1c3 d5e6 d1e2 g8f6 c3b5 e6e2 g1e2\r\ninfo depth 10 seldepth 16 multipv 1 score cp 23 nodes 57140 nps 1544324 tbhits 0 time 37 pv e2e4 e7e5 d2d4 e5d4 d1d4 g8f6 d4e5 d8e7 e5e7 f8e7 b1c3 b8c6 g1f3\r\ninfo depth 11 seldepth 19 multipv 1 score cp 23 nodes 83573 nps 1638686 tbhits 0 time 51 pv e2e4 e7e5 b1c3 b8c6 f2f4 e5f4 g1f3 f8b4 f1b5 g8f6 d2d3 e8g8 c1f4\r\ninfo depth 12 seldepth 19 multipv 1 score cp 27 nodes 194901 nps 1709657 tbhits 0 time 114 pv e2e4 e7e5 g1f3 b8c6 b1c3 g8f6 f1b5 c6d4 b5e2 d7d6 e1g1 c8d7 d2d3 d4e2 d1e2 h7h6\r\ninfo depth 13 seldepth 20 multipv 1 score cp 20 nodes 263167 nps 1742827 tbhits 0 time 151 pv e2e4 e7e5 g1f3 b8c6 b1c3 g8f6 f1b5 c6d4 b5e2 d7d6 e1g1 f8e7 f3d4 e5d4\r\ninfo depth 14 seldepth 20 multipv 1 score cp 27 nodes 395873 nps 1783211 tbhits 0 time 222 pv e2e4 e7e5 g1f3 b8c6 b1c3 g8f6 f1b5 c6d4 e1g1 d4f3 d1f3 c7c6 b5e2 d7d5 e4d5\r\ninfo depth 15 seldepth 21 multipv 1 score cp 21 nodes 841703 nps 1749902 tbhits 0 time 481 pv e2e4 e7e5 g1f3 b8c6 b1c3 g8f6 f1b5 c6d4 e1g1 a7a6 b5e2 d4f3 e2f3 f8c5 d2d3 d7d6 c1e3 c5e3 f2e3\r\ninfo depth 16 seldepth 25 multipv 1 score cp 26 nodes 1251153 nps 1732898 tbhits 0 time 722 pv e2e4 e7e5 g1f3 b8c6 b1c3 g8f6 f1b5 f8c5 e1g1 e8g8 f3e5 c6e5 d2d4 d7d6 c1g5 a7a6 b5e2 c5d4 d1d4 c8g4\r\ninfo depth 17 seldepth 25 multipv 1 score cp 30 nodes 1437380 nps 1735966 tbhits 0 time 828 pv e2e4 e7e5 g1f3 b8c6 b1c3 g8f6 f1b5 f8b4 a2a3 b4c3 d2c3 d7d6 c1g5 a7a6 b5d3 e8g8 e1g1\r\ninfo depth 18 seldepth 25 multipv 1 score cp 22 nodes 2143946 nps 1750160 tbhits 0 time 1225 pv e2e4 e7e5 g1f3 b8c6 b1c3 g8f6 f1b5 f8b4 e1g1 a7a6 b5c6 d7c6 f3e5 d8e7 d2d4 b4c3 b2c3 f6e4 c3c4 e8g8\r\ninfo depth 19 seldepth 25 multipv 1 score cp 17 nodes 3240480 nps 1740322 tbhits 0 time 1862 pv e2e4 e7e5 g1f3 b8c6 f1c4 g8f6 b1c3 f6e4 e1g1 f8e7 c3e4 d7d5 c4d3 d5e4 d3e4 c8g4 h2h3 g4f3 d1f3 e8g8 d2d3\r\ninfo depth 20 seldepth 27 multipv 1 score cp 17 upperbound nodes 6044219 nps 1716619 tbhits 0 time 3521 pv e2e4 e7e5 g1f3 b8c6 f1c4 g8f6 b1c3 f6e4 e1g1 f8e7 c3e4 d7d5 c4d3 d5e4 d3e4 c8g4 h2h3 g4f3 d1f3 e8g8 d2d3\r\ninfo depth 20 seldepth 27 multipv 1 score cp 23 lowerbound nodes 6439532 nps 1714921 tbhits 0 time 3755 pv e2e4 e7e5 g1f3 b8c6 f1c4 g8f6 b1c3 f6e4 e1g1 f8e7 c3e4 d7d5 c4d3 d5e4 d3e4 c8g4 h2h3 g4f3 d1f3 e8g8 d2d3\r\ninfo depth 20 seldepth 27 multipv 1 score cp 18 nodes 6650749 nps 1713227 tbhits 0 time 3882 pv e2e4 e7e5 g1f3 b8c6 f1b5 a7a6 b5c6 d7c6 e1g1 f8d6 h2h3 g8f6 d2d3 h7h6 a2a3 e8g8 b1c3 f8e8 c1e3 c8e6 e3d2\r\ninfo depth 21 seldepth 27 multipv 1 score cp 24 lowerbound nodes 8236169 nps 1706978 tbhits 0 time 4825 pv e2e4 e7e5 g1f3 b8c6 f1b5 a7a6 b5c6 d7c6 e1g1 f8d6 h2h3 g8f6 d2d3 h7h6 a2a3 e8g8 b1c3 f8e8 c1e3 c8e6 e3d2\r\ninfo depth 21 seldepth 27 multipv 1 score cp 30 lowerbound nodes 9111331 nps 1708481 tbhits 0 time 5333 pv e2e4 e7e5 g1f3 b8c6 f1b5 a7a6 b5c6 d7c6 e1g1 f8d6 h2h3 g8f6 d2d3 h7h6 a2a3 e8g8 b1c3 f8e8 c1e3 c8e6 e3d2\r\ninfo depth 21 seldepth 33 multipv 1 score cp 24 upperbound nodes 10962449 nps 1700923 tbhits 0 time 6445 pv e2e4 e7e5 g1f3 b8c6 f1b5 a7a6 b5c6 d7c6 e1g1 f8d6 h2h3 g8f6 d2d3 h7h6 a2a3 e8g8 b1c3 f8e8 c1e3 c8e6 e3d2\r\ninfo depth 21 seldepth 33 multipv 1 score cp 20 nodes 12079843 nps 1699949 tbhits 0 time 7106 pv e2e4 e7e5 g1f3 b8c6 f1b5 g8f6 e1g1 f8e7 b1c3 d7d6 d2d4 e5d4 f3d4 c8d7 d4f5 e8g8 c1f4 a7a6 b5c6 d7c6 c3d5\r\ninfo depth 22 seldepth 33 multipv 1 score cp 27 lowerbound nodes 13078297 nps 1699362 tbhits 0 time 7696 pv e2e4 e7e5 g1f3 b8c6 f1b5 g8f6 e1g1 f8e7 b1c3 d7d6 d2d4 e5d4 f3d4 c8d7 d4f5 e8g8 c1f4 a7a6 b5c6 d7c6 c3d5\r\ninfo depth 22 seldepth 33 multipv 1 score cp 20 upperbound nodes 14494880 nps 1694316 tbhits 0 time 8555 pv e2e4 e7e5 g1f3 b8c6 f1b5 g8f6 e1g1 f8e7 b1c3 d7d6 d2d4 e5d4 f3d4 c8d7 d4f5 e8g8 c1f4 a7a6 b5c6 d7c6 c3d5\r\ninfo depth 22 seldepth 33 multipv 1 score cp 27 lowerbound nodes 14816592 nps 1692744 tbhits 0 time 8753 pv e2e4 e7e5 g1f3 b8c6 f1b5 g8f6 e1g1 f8e7 b1c3 d7d6 d2d4 e5d4 f3d4 c8d7 d4f5 e8g8 c1f4 a7a6 b5c6 d7c6 c3d5\r\ninfo depth 22 seldepth 33 multipv 1 score cp 27 nodes 15948422 nps 1693577 tbhits 0 time 9417 pv e2e4 e7e5 g1f3 b8c6 f1b5 g8f6 e1g1 f8e7 b1c3 d7d6 d2d4 e5d4 f3d4 c8d7 d4f5 e8g8 f1e1 a7a6 b5c6 b7c6 f5e7 d8e7 c1f4 g8h8\r\ninfo depth 23 seldepth 33 multipv 1 score cp 21 upperbound nodes 18477321 nps 1688814 tbhits 0 time 10941 pv e2e4 e7e5 g1f3 b8c6 f1b5 g8f6 e1g1 f8e7 b1c3 d7d6 d2d4 e5d4 f3d4 c8d7 d4f5 e8g8 f1e1 a7a6 b5c6 b7c6 f5e7 d8e7 c1f4 g8h8\r\ninfo depth 23 seldepth 33 multipv 1 score cp 27 lowerbound nodes 19676418 nps 1688817 tbhits 0 time 11651 pv e2e4 e7e5 g1f3 b8c6 f1b5 g8f6 e1g1 f8e7 b1c3 d7d6 d2d4 e5d4 f3d4 c8d7 d4f5 e8g8 f1e1 a7a6 b5c6 b7c6 f5e7 d8e7 c1f4 g8h8\r\ninfo depth 23 seldepth 33 multipv 1 score cp 21 upperbound nodes 20501003 nps 1687881 tbhits 0 time 12146 pv e2e4 e7e5 g1f3 b8c6 f1b5 g8f6 e1g1 f8e7 b1c3 d7d6 d2d4 e5d4 f3d4 c8d7 d4f5 e8g8 f1e1 a7a6 b5c6 b7c6 f5e7 d8e7 c1f4 g8h8\r\ninfo depth 23 seldepth 33 multipv 1 score cp 22 nodes 21551487 nps 1686740 tbhits 0 time 12777 pv e2e4 e7e5 g1f3 b8c6 f1b5 g8f6 e1g1 f6e4 d2d4 a7a6 b5c6 d7c6 f1e1 e4f6 f3e5 f8e7 c2c4 e8g8 b1c3 c8f5 f2f3 h7h6 c1f4 f8e8 h2h3\r\n```"},"comment":{"url":"https://api.github.com/repos/official-stockfish/Stockfish/issues/comments/70388523","html_url":"https://github.com/official-stockfish/Stockfish/pull/216#issuecomment-70388523","issue_url":"https://api.github.com/repos/official-stockfish/Stockfish/issues/216","id":70388523,"user":{"login":"zamar","id":2694706,"avatar_url":"https://avatars.githubusercontent.com/u/2694706?v=3","gravatar_id":"","url":"https://api.github.com/users/zamar","html_url":"https://github.com/zamar","followers_url":"https://api.github.com/users/zamar/followers","following_url":"https://api.github.com/users/zamar/following{/other_user}","gists_url":"https://api.github.com/users/zamar/gists{/gist_id}","starred_url":"https://api.github.com/users/zamar/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/zamar/subscriptions","organizations_url":"https://api.github.com/users/zamar/orgs","repos_url":"https://api.github.com/users/zamar/repos","events_url":"https://api.github.com/users/zamar/events{/privacy}","received_events_url":"https://api.github.com/users/zamar/received_events","type":"User","site_admin":false},"created_at":"2015-01-17T23:06:28Z","updated_at":"2015-01-17T23:06:28Z","body":"I've opened a pull request #217 to fix the issue as proposed above..."}}