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First fail high drops in endgame
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Robert Hyatt



Joined: 27 Feb 2006
Posts: 15816
Location: Birmingham, AL
PostPost subject: Re: First fail high drops in endgame    Posted: Thu May 31, 2007 1:51 am Reply to topic Reply with quote
José Carlos wrote:
bob wrote:
José Carlos wrote:
Tony wrote:
hgm wrote:
Did you ever measure this quantity before (with different result)? It seems normal to me that it is more difficult to find cut-moves in an end-game, as the information that distinguishes the winning from the losing moves is much more distant. In the middle game it is often decided by what is on the to-square, but in end-games it is what is on the square you are heading to in a number of moves.


Yes,
otoh, in the endgame, you accidently choose the right (good enough) move more often.

But in fine 70 , 78% is way too low. that should be 98% or something. (No nullmove, no lmr)
I've never seen it that low. It almost looks like a random choice. I'm overlooking something obvious, but I haven't got a clue

Tony


I think that's normal behaviour due to hashing. If you prune much more due to hashing (like in Fine 70), you have less good-and-easy moves to search that would otherwise rise the FH at fist move rate.


that's backward. The better your hashing rate, the more frequently you have a good first move (hash move)...


I didn't make my point clear. What I meant is: if you probe the hash table and find a good move, you have good chances to have a cutoff in the first move, thus improving your FH at first move rate. But if the draft in the hash node is enough (and the score is good for a cutoff) you just return without searching. This case happens a lot in positions like Fine 70, and the nodes you really need to search are those you don't have good hashing information for them.
I haven't tested it, and my reasoning might be flawed, but seems logical to me.


It sounds like you are not measuring it like everyone else is. what we are basically counting is this:

On _any_ node where I get a fail high, what percentage of the time does the fail-high happen on the first move as opposed to a later move?

So a hash hit would not affect that whatsoever...

The key is that I have to fail high at this node, and not on the first move, before it hurts the statistic. One ply below a fail-high node you don't get a fail high at all... and you don't count those at all either when gathering this statistical data.

As far as your scenario about returning on the initial hash hit, you don't try a move, so you don't count that as a possible fail-high node and you don't pay any attention to whether the fail-high happens on the first or another move since none are searched anyway. The statistic only counts when you do try a move after failing to get a hash value that terminates the search here, and you actually try to search a move (the hash move going first of course, if there was one).
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Subject Author Date/Time
First fail high drops in endgame Tony Mon May 28, 2007 7:49 pm
      Re: First fail high drops in endgame H.G.Muller Mon May 28, 2007 8:45 pm
            Re: First fail high drops in endgame Tony Mon May 28, 2007 8:56 pm
                  Re: First fail high drops in endgame José C. Martínez Galán Tue May 29, 2007 9:06 am
                        Re: First fail high drops in endgame Robert Hyatt Tue May 29, 2007 3:12 pm
                              Re: First fail high drops in endgame José C. Martínez Galán Wed May 30, 2007 7:48 am
                                    Re: First fail high drops in endgame Tony Wed May 30, 2007 8:15 am
                                    Re: First fail high drops in endgame Robert Hyatt Thu May 31, 2007 1:51 am
                                          Re: First fail high drops in endgame José C. Martínez Galán Thu May 31, 2007 10:13 am
                                                Re: First fail high drops in endgame Robert Hyatt Thu May 31, 2007 4:30 pm
                                                      Re: First fail high drops in endgame Tony Thu May 31, 2007 7:16 pm
                                                            Re: First fail high drops in endgame Gerd Isenberg Thu May 31, 2007 7:58 pm
                                                                  Re: First fail high drops in endgame Tony Thu May 31, 2007 8:55 pm
      Re: First fail high drops in endgame Gerd Isenberg Mon May 28, 2007 9:41 pm
            Re: First fail high drops in endgame Tony Mon May 28, 2007 9:53 pm
                  Re: First fail high drops in endgame Gerd Isenberg Mon May 28, 2007 10:35 pm
                        Re: First fail high drops in endgame Tony Tue May 29, 2007 7:08 am
                              Re: First fail high drops in endgame Tony Tue May 29, 2007 11:13 am
      Re: First fail high drops in endgame Chan Rasjid Tue May 29, 2007 8:28 am
      Re: First fail high drops in endgame Robert Hyatt Tue May 29, 2007 3:10 pm
            Re: First fail high drops in endgame Tony Wed May 30, 2007 11:52 am
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