Author: Dave Gomboc
Date: 17:10:52 09/15/02
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On September 15, 2002 at 07:48:11, José Carlos wrote: >On September 15, 2002 at 07:44:18, Dave Gomboc wrote: > >>On September 15, 2002 at 04:27:44, martin fierz wrote: >> >>>i wish i knew :-) >>>i've forgotten what exactly i did in my 2-table code. i think i kept my >>>"important table" relatively empty, and probed "forever" until i found a place >>>to store the entry. "forever" was usually once, but on occasion more. >>>i never quite figured out why this turned out to be less efficient than a single >>>table. it's well possible that my implementation was bad... the other thing i >>>thought about was that in checkers, you often have a situation where you can >>>reach the same position with variable depth - happens in any endgame with kings. >>>now, i was relying on the depth from root to select the table i was probing in. >>>if a position stored in the "important" table turned up deeper in the search, it >>>might not have been found because it was looked up in the wrong table. the whole >>>thing with two tables seemed more complicated than with one, so i threw it out - >>>besides, the difference is probably really small, even with a better >>>implementation. >>> >>>aloha >>> martin >> >>It seems to me that other things being equal (e.g. you use them in the same >>way), one table with two slots is going to be slightly more efficient -- or at >>least certainly not less efficient -- than two tables with one slot, due to >>better prefetching and caching behaviour. >> >>Dave > > Except for the fact that you're forced to two equal size tables, whereas with >two separate tables you can choose a bigger one for always replace, which seems >to work better as a.r. is mainly useful near the leaves. > > José C. If you want a bigger always replace table, you can (for instance) use more cells in the one-table approach, e.g. 1:2 ratio would use three cells. Dave
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