[Ieghaehia9]

That in turn makes me wonder:

Given fixed opposition, finding a warrior that performs the best is an optimization problem. Maybe, for very small core sizes like a nano core, it would be possible to find the optimum directly by SAT or SMT instead of using evolution? Or would it be impractical even for those core sizes?

[slickytail]

I think it would, for all practical purposes, be impossible to determine an optimal warrior, even at very small core sizes. Not only is the search space huge but the evaluation function can take unbounded time to resolve. We should consider the halting problem embedded inside the optimization target as a clue to the problem's difficulty.

[Ieghaehia9]

That's the thing: Core War matches last a finite time (after which the match is judged a tie). So you have a finite memory space, finite time, and a finite number of match combinations. And for predetermined constant N, the bounded halting problem ("does the program halt within N steps") is in NP.

For the nano hill[1], the constants are: each warrior has a max of five lines of code, core size is 80 instructions, and a match lasts a maximum of 800 cycles.

If N = 1, it's clear that the best you can do is drop a bomb at a fixed location and hope you hit. So that is mostly a tie. For N=2, it's probably still not possible to do anything useful. With N = 10, perhaps a quickscan is possible. N = 800 -- who knows?

[1] https://corewar.co.uk/nano.htm