I feel like there might be a miscommunication here. Ultimately, what I’m trying to do is get the 2-norm of the gradient (first derivative), and add it as a term to the overall loss function. While it is true that the generator is linear, I’ve worked the math out in closed form and the second derivative (Hessian) of the loss function with respect to the parameters is in fact non-zero. Once again, the generator returns a proper graph and the gradient is non-zero, as expected. The problem is the discriminator, which is bilinear and should have a non-zero hessian no matter what. Sorry if I’m not doing a good job of explaining.