The author of the blog post used a deterministic algorithm; he observed some of his users using a non-deterministic one that appeared to work better. The fact

The author of the blog post used a deterministic algorithm; he observed some of his users using a non-deterministic one that appeared to work better. The fact that the algorithm is executed by a human matters, because the human processing system is optimised for highly parallel tasks, such as estimating which of many possible next moves is most likely to improve the solution.