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Frequency of 7-piece endgame positions
Posted: Thu Nov 15, 2018 10:47 am
by Pachnes
Hi, when we did download 6-piece Nalimov TBs about 12 years ago, there were 2 lists of the frequency of 6-piece positions, one for humay play, the other one for computer games. Does such lists also exist for 7-piece endgame positions?
I know that:
https://chess-db.com/public/research/en ... stics.html
Thomas
Re: Frequency of 7-piece endgame positions
Posted: Sun Dec 02, 2018 5:20 pm
by syzygy
They probably exist, but I don't remember seeing one.
It is clear that KRPPvKRP is the most important table.
To play out KRPPvKRP endings reliably, you need all tables that can be reached from KRPPvKRP by one or more promotions (both .rtbw and .rtbz). But if you just want to probe win/draw/loss, it is sufficient to have KRPPvKRP.rtbw and (importantly) all 6-piece tables.
Not all 6-piece tables are really needed for KRPPvKRP (only those that can be reached by captures and promotions), but if you're getting into 7-piece tables anyway, it does not seem worth the bother to be selective with the much smaller 6-piece tables.
So for analysis purposes you probably want to start with KXPPvKXP and KXPPvKYP.