Hi, author here. It could be called genetic programming, if one considers an expression to be a program.<p>Each individual in the population is encoded as a binary string representing an infix expression, with 0...9 becoming their binary representations (0001 through 1001) and the operators `+`, `-`, * , `&#x2F;` and `* * ` (exponentiation) represented as 1010 through 1110.