Author: Robert Hyatt
Date: 05:08:23 10/20/98
Go up one level in this thread
On October 20, 1998 at 00:34:41, Komputer Korner wrote: >On October 15, 1998 at 19:56:31, Robert Hyatt wrote: > >>On October 15, 1998 at 14:08:24, ed wrote: >> >>>On October 15, 1998 at 10:12:45, Robert Hyatt wrote: >>>>No it can't. Alpha/beta doesn't produce a score for *every* move searched. It >>>>produces a score for the first (hopefully best) move and then only proves that >>>>the score for every other move is lower, without determining how much lower. >>> >>>Yes, I do understand Alpha/Beta. Many a times, a pgm will have a tough time >>>deciding/alternating between move A or B or C, and, and it is these move A and B >>>and C that I want to see in the written analysis. Also, if the top 3 variations >>>is displayed on the screen, it gotta be also possible to save to a file, won't >>>you say? :) >>> >> >>One point: repeat after me slowly: "there is no way for alpha/beta to produce >>a best move, a second-best move and a third-best move, without tripling the >>time it takes to complete the search..." >> >>There are approximations. IE you get the best move at ply=10, but then it is >>replaced later by a better move at ply=10... you can show both PVs and say >>they are the best two. Or you can save the ply=9 pvs too, but that is much >>less accurate. >> >>Or you can do it the correct way: search all moves, save the best as "#1", >>then remove that move from the move list, and search all the moves except that >>one again. That gets #2. Repeat as often as you want, knowing that each >>search will take about as long as the previous one, since the best move takes >>90% of the total time... >> >> >> >>> >>>>It takes a second search to get the real score/PV for a second-best move... >>> >>>Hmmm... now that u mention it, it does make sense. > >Bob why can't programs present the move list either in a log file or on screen >in the alpha beta order? CSTAL does a 1 ply search to get the score evals for >each legal move but unfortunately it doesn't list the moves in the alpha beta >order of the engine search. Why couldn't a program do this? >-- >Komputer Korner Quite easy. With alpha/beta the only "order" we have is (1) best move and (2) rest of moves. There is no "order" to the moves other than one move is better than all the rest. No idea how much better, no idea where the other moves rank with respect to each other...
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.