This was obtained using an enhanced variation of the NRPA algorithm described in the IJCAI paper linked below.
I am using Morpion Solitaire as one benchmark problem in the development of new Monte Carlo search techniques. These techniques have now yielded a new record solution for the standard (5T) Morpion Solitaire game, with 172 lines:
In addition, these same techniques have also yielded a new record for the disjoint (5D) variant of Morpion Solitaire. For this variant, the previous record of 80 lines was found by Monte Carlo search (T. Cazenave, "Nested Monte-Carlo Search." IJCAI 2009). The new record has 82 lines:
The new techniques used to set these new records are based on a combination of nested search (somewhat like: T. Cazenave, "Nested Monte-Carlo Search." IJCAI 2009) and machine learning of Monte Carlo playout policies (learning-based playout policies have also been used in the game of Go: D. Silver & G. Tesauro, "Monte-Carlo Simulation Balancing." ICML 2009).