I understand, but isn't the opening decision tree depth IS the zero sum nature playing out?? the depth of the opening decision tree exactly what you'd expect in a zero sum strategic game? In any highly competitive zero sum environment (poker, business, etc.), players will inevitably explore and optimize every available edge, ESPECIALLY preparation? That was the fun of it I thought? Any arms race in opening theory is a natural consequence of the zero sum structure... if memorizing 25 moves gives you an edge over someone who memorized 23, the competitive pressure forces everyone deeper into preparation?