Where are the terms DTZ and DTR defined?
Wikipedia says: Haworth has discussed two other metrics, namely "depth to zeroing-move" (DTZ) and "depth by the rule" (DTR). These metrics correct for the fifty move rule, but few tablebases with these metrics have been released to the public Reference: G. McC. Haworth (March 2000). "Strategies for Constrained Optimisation" (PDF). ICGA Journal. Retrieved on 2007-04-01 is given , but I was not able to retrieve the paper from the link
http://www.is.reading.ac.uk/common/publ ... /02124.pdf though I tried several times the last few days.
Aaron Tay's FAQ gives: In addition, Distance to zeroing (DTZ) and the superior Distance to rule (DTR)tablebases have being proposed to overcome the fact that DTM and DTC do not recognise the fifty move rule. Only in theory so far.
Wilhelm-Readme gives:
DTZ = Distance to Zeroing Move, this means the distance (measured in moves too) to the move which causes the restart of the move counter until a draw by the 50-move rule would occur or until the mate. In pawnless endgames, the draw due to the 50-move rule can only be avoided by capturing a piece, therefore DTC =DTZ for pawnless endgames.
DTC50 and DTZ50 are in principle the same as DTC and DTZ, but with respect to the 50-move rule. This means that all positions which would be drawn according to the 50-move rule are effectively marked a draw. But note that with DTC50, pawn moves which do not fulfil a DTC criterion are not considered as moves resetting the 50-move counter. DTC(n) and DTZ(n) are the generalisations of DTC50 and DTZ50 for a more general n-move rule.
