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Steven Edwards
Joined: 13 Mar 2006
Posts: 3076
Location: Mud, Bugs, and Taxes, NH, USA
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Uri Blass
Joined: 08 Mar 2006
Posts: 5958
Location: Tel-Aviv Israel
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 Posted: Sat May 05, 2007 5:14 am Post subject: Re: Symbolic: BWTC.0001 (12 nodes) |
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How do you choose your candidate moves?
I see that
Qxf7+ is one of the candidate moves but Bxf7+ is not one of them.
What is the reason?
I think that it is more logical to consider first Bxf7+ and not Qxf7+ that sacrifices the queen or Bh7+
Note that Bxf7+ also can force mate more slowly based on analysis
The only reason that I can understand for not prefering Bxf7+ in the search is the fact that Bxf7+give black 3 legal move when Qxf7+(like Bh7+ give black 2 legal moves) but a rule that always prefers searching first check that restricts the number of moves of the opponent regardless of material seems illogical and when it may be good for some tactical positions I cannot believe it can be good for tactics in general.
Uri |
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Steven Edwards
Joined: 13 Mar 2006
Posts: 3076
Location: Mud, Bugs, and Taxes, NH, USA
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| Posted: Sat May 05, 2007 11:05 am Post subject: Re: Symbolic: BWTC.0001 (12 nodes) |
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1. Bxf7+ was not included in the search because a forced mate was located first. The search concludes as soon as a forced result at the root is detected. The mate search does not attempt to find faster mates after a sure mate of any length is discovered.
No claim is made that the mate attack/defend metrics are good for anything other than mate attacks and defenses. |
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Uri Blass
Joined: 08 Mar 2006
Posts: 5958
Location: Tel-Aviv Israel
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| Posted: Sat May 05, 2007 1:48 pm Post subject: Re: Symbolic: BWTC.0001 (12 nodes) |
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| sje wrote: |
1. Bxf7+ was not included in the search because a forced mate was located first. The search concludes as soon as a forced result at the root is detected. The mate search does not attempt to find faster mates after a sure mate of any length is discovered.
No claim is made that the mate attack/defend metrics are good for anything other than mate attacks and defenses. |
It means that Qxf7+ is ordered before Bxf7+.
It is counter intuitive and as a human Bxf7+ is the first move that I look at it.
If you use SEE to decide about order of moves then
Bxf7+ seems better than Qxf7+.
Uri |
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Steven Edwards
Joined: 13 Mar 2006
Posts: 3076
Location: Mud, Bugs, and Taxes, NH, USA
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| Posted: Sat May 05, 2007 8:17 pm Post subject: Re: Symbolic: BWTC.0001 (12 nodes) |
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| Uri Blass wrote: |
It means that Qxf7+ is ordered before Bxf7+.
It is counter intuitive and as a human Bxf7+ is the first move that I look at it.
If you use SEE to decide about order of moves then
Bxf7+ seems better than Qxf7+.
Uri |
1. Qxf7+ comes before 1. Bxf7+ because it does more damage to the black king's flight square set. There is no SEE used for mate attack selection. |
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Steven Edwards
Joined: 13 Mar 2006
Posts: 3076
Location: Mud, Bugs, and Taxes, NH, USA
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| Posted: Sat May 05, 2007 10:39 pm Post subject: Re: Symbolic: BWTC.0001 (12 nodes) |
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| I've updated the file on the web site. The output is almost the same as the first version except that Symbolic now outputs the average branching factor. And that's 1.22 for the given search. |
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Steven Edwards
Joined: 13 Mar 2006
Posts: 3076
Location: Mud, Bugs, and Taxes, NH, USA
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| Posted: Wed May 09, 2007 11:01 am Post subject: Re: Symbolic: BWTC.0001 (12 nodes) |
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I've updated the file on the web site again. The visible change this time is that the node marks have been expanded a bit and are now output to HTML in ASCII order to help with debugging.
Straight from the source, here is the rather flexible list of node marks:
| Code: |
;; Node marks
;;
(defconstant TheNodeMarks
'(
IsAlternate
IsBTM
IsBook
IsCandidate
IsCertain
IsCheckResponse
IsCheckmate
IsDraw
IsDrawByFiftyMoveRule
IsDrawByInsufficientMaterial
IsDrawByStalemate
IsDrawByThreefoldRepetition
IsExtension
IsFM
IsForced
IsForcedDraw
IsForcedLose
IsForcedMate
IsFullyExpanded
IsInCheck
IsInDoubleCheck
IsNoMovesAvailable
IsOnlyOneMoveAvailable
IsOriginal
IsRoot
IsSM
IsSecondRepetition
IsSingletonResponse
IsTablebase
IsTerminal
IsWTM
))
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