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Subject: Re: To Ed Schröder

Author: Tom Likens

Date: 11:00:13 05/25/04

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On May 24, 2004 at 14:39:36, Ed Schröder wrote:

>On May 24, 2004 at 13:09:42, José Carlos wrote:
>
>>On May 24, 2004 at 12:39:35, Ed Schröder wrote:
>>
>>>On May 24, 2004 at 12:07:56, Russell Reagan wrote:
>>>
>>>>On May 24, 2004 at 10:13:33, Ed Schröder wrote:
>>>>
>>>>>>It would also be interesting to hear some background - how you arrived at what,
>>>>>>what else you tried & discarded, how confident you are about it, any general
>>>>>>thoughts, etc.
>>>>>
>>>>>That would take too much to read, I prefer to stay on topic and as short as
>>>>>possible. Your question is much better suited for a forum, so: I feel my way of
>>>>>doing king safety is okay, I can't say that about the evaluation of passed
>>>>>pawns, I feel most insecure about it.
>>>
>>>>It would be interesting to know how you determine if a change you make is an
>>>>improvement (if you are allowed to tell us, of course).
>>>
>>>You guessed well, I can't tell.
>>>
>>>Ed
>
>>  But Ed, you surely had a method to determine that way before meeting
>>Christophe (which is the reason, I guess, you can't tell now).
>
>Yes.
>
>
>>Could you comment
>>on your pre-Christophe testing methods?
>>  Thanks in advance.
>
>I can tell you one part, here is. I have testsets that contain well selected
>positions (tactics, positional, midgame, endgame etc.) Depending on the changes
>I have made I run a specific testset (or testsets) as first step in my own
>text-based DOS interface, it serves as a first smell. When finished I can
>produce several reports, such as to compare the results with a previous version.
>
>A screenshot:
>
>Rebel ... version RXP   05-07-2003
>(REBEL XP) (A-2000)  CV=100
>
>Rebel ... version M02   04-04-2004
>(KILLER - KD1|KD2|KD1-2|KD2-2) CV=RXP
>
>Number of searched positions : 260
>Number of different moves    : 5
>Number of different scores   : 8       (Interval score = 0.10)
>Number of different times    : 22      (Interval time = 10%)
>
>Total time (version 1) : 00:57:56      Nodes 3.187.570
>Total time (version 2) : 00:57:32      Nodes 3.151.571
>Total percent  :  1%                       (1.14%)
>
>Score 0.01 - 0.10   22                 Nodes faster vs slower  119 - 117
>Score 0.10 - 0.25   5                  Nodes       (1%)        119 -  51
>Score 0.25 - 0.50   1                  Nodes       (2%)         61 -  34
>Score 0.50 - 0.75   0                  Nodes       (3%)         42 -  26
>Score 0.75 - 1.00   1                  Nodes       (4%)         36 -  20
>Score 1.00 - 2.00   0                  Nodes       (5%)         31 -  19
>Score greater 2.00  1                  Nodes       (9%)         12 -  13
>
>Compare on <A>ll  <M>ove  <S>core  <T>ime  <N>odes  <Q>uit
>
>=================

Ed,

Thanks for posting this but I want to make sure I understand what
you've written.  Specifically, I have a question about the
"Nodes faster vs slower" section.  Does the line:

Nodes   (1%)   119 - 51

indicate that version 2 had 119 positions where it searched 1% fewer
nodes than version 1 *and* 51 positions where it searched 1% more
nodes (or am I missing the point altogether)?

Also regarding the two nodes that ran much longer, did they also
search  a proportionate number of extra nodes.  I'm wondering
because I would have expected them to show up in the
"Nodes-Overview" section.

And finally, I'm also wondering if it would be advantageous to have
a "Time-Overview" section analogous to the score and nodes data,
(actually, it sounds like you may already have this in the other
analysis funtion you mentioned).

regards,
--tom

>
>In this specific case (it is just a random example) I have tested a change in
>move-ordering swapping the order of killer-moves to see if it gains anything.
>
>The report says that 260 positions have been searched, that the change produces
>5 different moves, 8 different scores outside an interval of 0.10, 22 times
>outside an interval of of 10%. Of course intervals are flexible.
>
>Then the report shows that the change is good for a 1% speedup (ahem) in time as
>well as nodes. The "Nodes-Overview" (faster vs slower) reveals that there are
>more positions that run faster than slower which in this specific case is an
>important piece of information because the speed gain is so low and from another
>analysis function I could see the 1% was polluted by 2 positions that ran much
>longer and by skipping them the speed gain was higher. The consistency as shown
>in the nodes-overview becomes a dominant factor to accept a change (or not) in
>doubtful cases like this one.
>
>Another function (which I think every serious chess programmer should have) is
>the "Nodes-compare" function. It will report every difference in nodes of the
>tested positions, 260 in this case. It has been extremely useful for me to avoid
>bugs.
>
>Ed



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