In this case you ought to say "there is an order of magnitude more software available...(base Y)".

Otherwise, using your argument, for the same numbers you could equally say "there is a constant factor more more software available", in that for X ARM apps there are X*c x386 apps for c > 1

Obviously this is true for the constant c = X^(Y-1)

As soon as you start playing with two constants, there is an infinite number of functions that can interpolate between them (and hence describe their relationship). This includes exponential functions, polynomial, constant, sinusoidal, linear...

Canonical GAs are never the correct tool for a problem. They combine a crude random local search (mutation) with the cross-over operator that is intended to splice partial solutions. The trouble is that even on problems designed to be exploited by GAs, like the Royal Road, a random restart hill-climber will perform better with the same number of fitness evaluations.

I'm not as familiar with GP, but given the minute number of attributes quoted and millions of fitness evaluations... I'd say a typical greedy tree learner would perform much, much better.