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Subject: Re: Squashing Hash Table Bugs

Author: Robert Hyatt

Date: 18:23:28 05/29/04

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On May 29, 2004 at 11:10:47, James Swafford wrote:

>In a recent post, Tord suggested setting a flag in
>the search when the hash table suggests a fail high, and
>testing whether the search would indeed fail high.
>
>The idea seems so simple I'm embarassed I haven't thought
>of it before. :)
>
>I've been 'pretty sure' for a long time that I've got some
>nasty hash bugs.  I'm in the mood to exterminate them.
>
>Last night I implemented Tord's idea and, to my dismay
>(but not to my surprise) my hash table is saying 'fail
>high' when the search wouldn't have failed high.  And-
>it doesn't take very long. :)

This is _not_ necessarily a bug.

Your hash table entry can have a draft > depth, while the real search you will
do will only go to depth.  A deeper search might say fail high while a shallower
search fails low.

That test is no good...


>
>This seems like a nasty thing to debug.  I'm comtemplating
>how I might go about it.  I'm hoping some of you can
>provide some suggestions...
>
>--
>James



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