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[[FILE:John William Waterhouse oracle 1884.png|border|right|thumb|[[Arts#:Category:John William Waterhouse|John William Waterhouse]] - ''Consulting the Oracle'' <ref>Consulting the Oracle by [[Arts#:Category:John William Waterhouse|John William Waterhouse]], 1884, showing eight priestesses in a temple of prophecy, [https://en.wikipedia.org/wiki/Oracle Oracle from Wikipedia]</ref> ]]

This seemed most useful in the [[Endgame|endgame]] when actually reaching the culmination of a play might be beyond the [[Depth|search depth]], and where [[Tactics|tactics]] did not dominate as much as they do in the [[Middlegame|middle game]]; for example, Duchess was quite capable of finding long King maneuvers that might take the King far away from simpleminded heuristics such as "[[King centralizationCentralization|centralize the King in the endgame]]" and that were too deep to be found by a direct search. It wasn't perfect; it could not take into account the changes in strategy that might be dictated by a radically different structure encountered deep in the search, but it seemed to be better than nothing.

A second departure from other commercial programs has been the simplification of the [[Evaluation functionFunction|evaluation function]] as applied to the [[Leaf Node|end nodes]] of the tree [[Search|search]]. The programs instead rely heavily on specific chess [[Knowledge|knowledge]] which is concentrated into a special [[Piece-Square Tables#Preprocessing|preprocessor]] which interfaces to the tree search primarily through the [[Score|scores]] associated with specific ply-one [[Moves|moves]]. This ides of a ply-one move preprocessor was originally implemented in the program [[Tech]] by [[James Gillogly]] in the late 1960s. Although Tech only achieved a high 1400 rating running on a large computer, the strategy has certain appeal. First, chess tree searching has become very efficient, and second, the interaction problems associated with putting ever increasing amounts of chess knowledge in the tree become formidable. It has become apparent to that this rather simple approach might contain the structure of a master level microcomputer program.

The main design criterion for successor [[Nimzo|Nimzo-3]] was combining the positional play of Nimzo-2 with the [[Tactics|tactical]] strength of a program like [[Fritz]]. Nimzo-2 was developed on an [[x86|486/50 MHz]] [[IBM PC|PC]], which calculated about 3,000 [[Nodes per secondSecond|nodes per second]]. Thereof 60 to 70 percent was spent/wasted in the [[Evaluation|leaf evaluation]] routines. Hence, a major improvement in speed and thus in tactical strength could only be obtained by performing most of the evaluation either in the root or the interior of the [[Search Tree|search tree]]. So, Nimzo-3 became a [[Chess Genius|Genius]]/[[Fritz]]-like program with a complex root evaluation, called Oracle, similar to [[Hans Berliner|Berliner's]] Oracle, and with a very simple, mainly first order evaluation at the [[Leaf Node|leaves]] <ref>This approach seems to have been invented by [[Kaare Danielsen]] for his program [[CXG Star Chess#Advanced|CXG Advanced Star Chess]], Quote from [[Chrilly Donninger|Donninger's]] CHE paper</ref>. Nimzo-3 spends about 10 to 20% on leaf evaluation, its node rate has increased by 400% up to 12,000 nodes/second on the same hardware.

| The term pre-processing is normally used in the context of an evaluation function. It's a process where you make most of your evaluation decisions BEFORE the [[Search|search]] begins. Typically you determine where each piece should go and essentially build a 64 square table for each piece type of each color on the chess board. You might decide that the c file is [[Open fileFile|open]] and so you give rooks a big bonus if they can get to the c file. Once you make this decision it doesn't change during the search. So if the c file suddenly gets blocked during the search, the rooks won't know this and still try to get on the c file.

* [[Videos#MichaelHedges:Category:Michael Hedges|Michael Hedges]] - [https://en.wikipedia.org/wiki/Oracle_%28Michael_Hedges_album%29 Oracle] / Fusion of the Five Elements, [https://en.wikipedia.org/wiki/YouTube YouTube] Video