deep alpha-beta pruning?

[edwardyu]

I found from the web :
http://www.gtryfon.demon.co.uk/bcc/Comp ... ormcmp.htm
that there exists some deep alpha-beta pruning in searching. Why is this not mentioned elsewhere, or is it not worthwhile to be implemented in any chess engine?

[Gerd Isenberg]

I found from the web :
http://www.gtryfon.demon.co.uk/bcc/Comp ... ormcmp.htm
that there exists some deep alpha-beta pruning in searching. Why is this not mentioned elsewhere, or is it not worthwhile to be implemented in any chess engine?

Todays recursive standard alpha-beta implementations do deep cutoffs implicitly. You don't care wether your beta (aka parent's -alpha in negamax) was improved at the parent or grand-grand-parent. HGM recently quoted he missed deep cutoffs in Usurpator I, because he didn't pass alpha through the recursive call. I guess deep cutoffs were also missed in the Kotok-McCarthy-Program ...