[soravux]

The best answer I can provide is: The code is there. There are no heuristics in it. Everytime you run it, you get different results (because of random initialization seeds and the stochastic nature of EA). It may find the (a - (x >> 1)) equation on a specific execution, or not. Over the runs I made, this equation (or similar) was the most popular and nothing come close to it. In fact, it finds a lot of other optimizations; either less accurate or way more complex. I remember getting tens and tens of operations in equations with "bof" accuracies.