It means f(x) = 1 is true for some particular x’s, e.g., f(x_1) = 1 and f(x_2) = 1, there are distinct mechanisms for why f(x_1) = 1 compared to why f(x_2) = 1, and there’s no efficient discriminator that can take two instances f(x_1) = 1 and f(x_2) = 1 and tell you whether they are due to the same mechanism or not.
It means f(x) = 1 is true for some particular x’s, e.g., f(x_1) = 1 and f(x_2) = 1, there are distinct mechanisms for why f(x_1) = 1 compared to why f(x_2) = 1, and there’s no efficient discriminator that can take two instances f(x_1) = 1 and f(x_2) = 1 and tell you whether they are due to the same mechanism or not.