R is a common name for a constant or variable signifying depth reduction used in the Null Move Pruning^{[1]}, Null Move Reductions and independently in Multi-Cut^{[2]}. In many null move implementations it is either 2 or 3, the exact formula being depth - R - 1.

Variable Reduction

When R becomes a variable, then we say that a program uses adaptive null move pruning, first described by Ernst A. Heinz^{[3]}, using R=3 when normal search depth exceeds 6 plies and R=2 otherwise, while more recently most engines account increased search depth with greater reductions ^{[4]}.

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Home * Search * RRis a common name for a constant or variable signifying depth reduction used in the Null Move Pruning^{[1]}, Null Move Reductions and independently in Multi-Cut^{[2]}. In many null move implementations it is either 2 or 3, the exact formula being depth - R - 1.## Variable Reduction

WhenRbecomes a variable, then we say that a program uses adaptive null move pruning, first described by Ernst A. Heinz^{[3]}, using R=3 when normal search depth exceeds 6 plies and R=2 otherwise, while more recently most engines account increased search depth with greater reductions^{[4]}.## Forum Posts

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## References

1993).Null Move and Deep Search: Selective-Search Heuristics for Obtuse Chess Programs.ICCA Journal, Vol. 16, No. 32001).Multi-cut Alpha-Beta Pruning in Game Tree Search.Theoretical Computer Science, Vol. 2521999).Adaptive null-move pruning. ICCA Journal, Vol. 22, No 3## What links here?

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