But we can distinguish i and -i by convention and keep consistent right? Akin to sending the distant alien a sample? It’s in the abstract that we can’t really t

But we can distinguish i and -i by convention and keep consistent right? Akin to sending the distant alien a sample? It’s in the abstract that we can’t really tell them apart. But as soon as we are given any kind of starting point to form a convention, like the first mathematical textbook tells us which is i and which is -i, we have enough? I think of an unlabeled, unconnected graph of two vertices. If I just pick one and call it A say by pointing to it, that’s enough. The trick is to do it for limited communication partners like the alien right?