[tspdpsgv] Strength of a position by defending it

Measure "some characteristic" of a chess position by having a weaker chess program defend it against a stronger program, perhaps the same program set at different search depths.

Even tricker would be to have the stronger program deliberately aim for "complications", attempting to trip up the weaker program.

The goal is to determine whether a position evaluated by computer as, say, +2.0, is a position a human could easily win, or can only be won by a computer finding a long string of tricky moves.  Perhaps call this "some characteristic" "robustness of the score".