[ofydvrjs] Endgame trainer

Create a training program (a puzzle program) for a tough chess endgame which learns which defenses you know how to defeat and correspondingly steers you toward unfamiliar positions.

Conversely, a computer attacker with (perhaps stated) holes in its repertoire which the human defender must exploit to defend as long as possible (perhaps indefinitely).

First step is to formally define the endgame strategies and implement them as an algorithm, not just a tablebase.  This information is currently written in books as natural language. Collaborative formalization?

Inspired by youtube user queenvrook regarding the tough queen versus rook endgame.

Incidentally, the few cases of the RP vs R converting to Q vs R seem like a hellish concatenation of a pair of extremely tough endgames. The defender may wish to steer KRPKP toward KQKR if at all possible.