ISDA compliant tie-breaking for PL

I was thinking in another tie-breaking for the PL ranking system ([[Wikipedia:Copeland's method|Copeland]]).
Currently it uses full APS as tie-breaking, but it sacrifices [[Wikipedia:Independence of Smith-dominated alternatives|ISDA]], which is a key property from [[Wikipedia:Copeland's method|Copeland]] to prevent low ranked competitors from interfering with the top ones ([[King maker|king-making]]).

Tie-breaking could use only APS between tied competitors instead, to preserve [[Wikipedia:Independence of Smith-dominated alternatives|ISDA]].

Example 1:
[[DrussGT]], [[Diamond]] and [[Tomcat]] are all tied in first place. Tie-breaking score for [[DrussGT]] would use only [[Diamond]] and [[Tomcat]]. Score for [[Diamond]] would use [[DrussGT]] and [[Tomcat]]. Score for [[Tomcat]] would use [[DrussGT]] and [[Diamond]]. As if those 3 were the only competitors in the rumble.

Example 2:
[[DrussGT]] and [[Tomcat]] are tied in first place. Tie-breaking score for [[DrussGT]] would use only [[Tomcat]]. Score for [[Tomcat]] would use [[DrussGT]]. It would be a head-to-head comparison between the 2.

Competitors not tied to anyone else can have any tie-breaking score, as it would not change the ranking.