Author: Robert Hyatt
Date: 12:11:35 09/15/04
Go up one level in this thread
On September 15, 2004 at 14:48:51, Gerd Isenberg wrote: >On September 15, 2004 at 12:17:14, Robert Hyatt wrote: > >>On September 15, 2004 at 09:53:53, Stuart Cracraft wrote: >> >>>Hi, >>> >>>Anyone know of some code somewhere that implements >>>at least part (or all) of the originally described >>>singular extension and/or any modifications to it that >>>have proven worthwhile (if any)? >>> >>>I am curious what mediocre (or better) results people >>>have gotten with singular extension. Originally Anantharaman >>>hypothesized that it wouldn't be good at the slower >>>speeds of most programs at the time and would require >>>fast speeds to show effect. Has this proven true or >>>false in the intervening 15 years? >>> >>>Is singular extension now generally discredited as a >>>non-reproducible singularity in and of itself? >>> >>>Thanks, >>> >>>Stuart >> >> >>It worked in Cray Blitz for the last two years it competed. How much it >>improves overall chess skill is debatable. Early on the DB guys claimed very >>significant improvements. Later more thorough testing showed that there was >>definitely an improvement, but not as large as originally thought. >> >>I have not really spent a lot of time doing this in Crafty although there is a >>SE version roaming around that I released, but it didn't do SE like the DB guys >>did. Their implementation is not a 2 week deal. Expect to spend a year getting >>it working as they did, if not more. >> >>Some commercial programs use variants. IE Wchess used the PV-singular part of >>singular extensions, but not the fail-high part the DB guys defined. > >There are so many applications of a reduced/modified pre-search to gain more >informations for better move sorting, pruning, extensions and reductions. > >1. Internal iterative deepening >2. Nullmove oberservation or pre-verification >3. Looking for singularity >4. Looking for multiple beta cuts > >I wonder whether there is an approach to combine a few of them on cut-nodes. Hsu's paper defined singular extensiosn for PV nodes and CUT nodes. His paper said "we have found no useful definition for a singular move at an ALL node however.." > >Btw. considering minimal tree node types, pv-, cut- and all nodes >(pv most left, cut successor from pv or all, all successor from cut) >What information may we gain, for a cut node, where only one successor has to be >searched in a minimal tree, if it behaves like an all node? All I can immediately think of is that your move ordering is bad at that CUT node, because by definition you only need to search 1 move at a CUT node, and not even the best move, just one "good enough to produce a cutoff." >E.g. if static eval <= alpha or even first move doesn't improve alpha? > >Thanks, >Gerd
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