Calculating Ultra-Strong and Extended Solutions for Nine Men's Morris,
  Morabaraba, and Lasker
  The strong solutions of Nine Men's Morris and its variant, Lasker Morris are
well-known results (the starting positions are draws). We re-examined both of
these games, and calculated extended strong solutions for them. By this we mean
the game-theoretic values of all possible game states that could be reached
from certain starting positions where the number of stones to be placed by the
players is different from the standard rules. These were also calculated for a
previously unsolved third variant, Morabaraba, with interesting results: most
of the starting positions where the players can place an equal number of stones
(including the standard starting position) are wins for the first player (as
opposed to the above games, where these are usually draws).
  We also developed a multi-valued retrograde analysis, and used it as a basis
for an algorithm for solving these games ultra-strongly. This means that when
our program is playing against a fallible opponent, it has a greater chance of
achieving a better result than the game-theoretic value, compared to randomly
selecting between "just strongly" optimal moves. Previous attempts on
ultra-strong solutions used local heuristics or learning during games, but we
incorporated our algorithm into the retrograde analysis.
