Author: Ed Schröder
Date: 05:49:22 08/03/98
Go up one level in this thread
>>Like to add that I often have noticed such a "false-fail-high" is rewarded >>in the next iteration after all. It has puzzled me for years. A few years >>ago I made a test-version that always took a "fail-high" as best move, >>false or not. Results were not better but also not worse. >>Similar experiences? >>- Ed - >I always accept the fail-high move immediately. >There are parameters that you are important that you don't mention: What size >window is used during normal search ? If it's zero-width, or very small, then >fail-high doesn't mean it's much better than the previous best, and you can >take the new move or leave it. If you use a 0.3-0.5 window, as I do, fail-high >means it's clearly better than the previous, even it later fails low. Since years I use aspiration search with a 0.50 window. In case of a "fail-low" I set alpha to "low-value". In case of a "fail high" I do: - set alpha and beta to "low-value" in case of the first move of the iteration. - set alpha to "low-value" in all other cases. In case of no "fail-high" or "fail-low" I create a new beta window (alpha+0.15) - Ed - >Also, what window do you use on the re-search that fails low ? If you use >new-alpha+1 to infinity, then maybe the fail-low happened because the value is >exactly new-alpha. If you use a window of old-alpha to infinity, then a >fail-low indeed makes the move suspicious. >Amir
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