Author: Uri Blass
Date: 12:43:43 09/16/00
Go up one level in this thread
On September 16, 2000 at 15:07:43, José de Jesús García Ruvalcaba wrote: >On September 16, 2000 at 14:33:51, guy haworth wrote: > >>Consider the following position from Ken Thompson's 6-man EGT site: >> >>8/8/7B/5B2/3K4/8/2k5/n6n b - - 0 1 >> >>It is a 'win' for White and also a maxDTC and maxDTM position. >>DTC = 76 plies (38 moves) and DTM = 212 plies (106 moves). >> >>Black cannot protract the first phase beyond 50 moves and therefore might be >>best advised to maximise DTM and (within that, should a choice occur) minimise >>DTC. >> >>Similarly, White might be best advised to do the following in order: >> keep the first phase down to 50 moves or less, >> minimise DTM (Depth to Mate), and >> maximise DTC (Depth to Conversion). >> >>These White/Black strategies leadd to what I call an SGM-C-_SM+C+ line. >>However, White's (few) options and a Black defence along these lines can lead to >> >>[D] 6B1/1K6/1B6/8/8/8/3nk3/8 b - - 0 40 >> >>and a KBBKN 2nd-phase allowing a 50-move draw claim. >> >>So, the question is "Can this position be won under a 50-move rule, and if so, >>how, given 'best play' by Black?". >> >>G > > The way to answer this question (and several others) is to produce a new set of >tablebases, which are neither DTM nor DTC. > For positions which are won but might (or might not) infringe the 50-move rule, >two numbers are stored: the number of conversions needed to deliver mate and a >new number, let's call it Marimar number. I do not think that you need Marimer numbers in order to know if the position is won or a draw. Distance to conversion is enough if you start from the simple cases and define distance that is bigger than 100 plies as a draw. conversion for a position when the distance to conversion is more than 100 plies is a draw because of the fact that it is conversion to a position that is known as a draw from previous conversion tablebases. The marimer numbers can help when you play for a win in drawn position because you are going to play for positions with a lower marimer number but it is not always the best idea to play for the smallest marimer number in a drawn position. It is possible that you get marimer number of 11 after 99 plies with no conversion. You have 2 options: 1)to capture and get a position with marimer number 101 when you have practical chances of win. 2)not to capture and get a position with marimer number 10 when the opponent practically claims a draw by the 50 move rule. playing for the smallest marimer number is not the best choice in this case. Uri
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.