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Subject: Re: The Tobacco fields of my youth -- Parallel algorithms

Author: Robert Hyatt

Date: 07:31:54 02/27/04

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On February 26, 2004 at 17:04:23, Charles Roberson wrote:

>On February 26, 2004 at 12:06:10, Anthony Cozzie wrote:
>
>>On February 26, 2004 at 11:18:07, Charles Roberson wrote:
>>
>>>
>
>>>     The second algorithm reminds me of Bob's paper on DTS or any other work
>>>     stealing approach.
>>
>>I don't think DTS really suggested a split strategy (other than split at ALL
>>nodes if possible).  Bob's paper is more, "how can we design a parallel
>>structure so that we can split anywhere in the tree".  Once you have a working
>>DTS implementation, you can split however you want . . .
>>
>>anthony
>
>   Work stealing algorithms typically try to reduce the overhead of finding a
>  processor that needs help by assigning the free processor to the one the has
>  the most work left to do. I see Bob's work as help for work stealing
>  algorithms.


The problem is, in alpha/beta this is hard to determine (most work left to do).
You might be about to terminate the search due to a fail-high, for example, but
there is not much that would let you know that.  It's a very difficult problem,
and it is why the YBW-approach is what most everyone uses.  IE DTS has YBW-like
ideas, although most of what DTS does has to do with the mechanics of doing the
parallel search, rather than determining where to further sub-divide the work...



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