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SNOWIE'S ECCENTRIC ENGLISH

Posted By: Ray Kershaw
Date: Thursday, 4 February 2010, at 5:20 p.m.

Snowie compares checker plays or cube actions in a match in terms of their match winning chances (mwc). Because the difference between two mwc's varies with the match score (typically being small at the start of a long match but large towards the end), Snowie transforms match mwc's into "equivalent to money game normalized cubeful equity" (emg for short). This does not affect the ranking of the checker plays or cube actions but it enables Snowie to say whether failure to pick the best play or action is an "error" or a "blunder".

OK, that's fine. I even understand how Snowie calculates emg. (The normalized emg scale has a value of +1 corresponding to mwc if a single is won at current cube level and of -1 corresponding to mwc if a single is lost at current cube value. It is assumed to be linear beyond and within these limits.)

But I do not see how emg is in any sense an "equity". For example, leading 2-1 to 3, post-Crawford, you stupidly make a last roll double with checkers on 5,2. Your mwc after a take is 52.78% (19/36)(favourite) and your emg is -0.889 (negative).

How do other bots describe this ? And can any meaning be attached to emg ?