ICE-BeeM: Identifiable Conditional Energy-Based Deep Models Based on Nonlinear ICA

Despite the growing popularity of energy-based models, their identifiability properties are not well-understood. In this paper we establish sufficient conditions under which a large family of conditional energy-based models is identifiable in function space, up to a simple transformation. Our results build on recent developments in the theory of nonlinear ICA, showing that the latent representations in certain families of deep latent-variable models are identifiable. We extend these results to a very broad family of conditional energy-based models. In this family, the energy function is simply the dot-product between two feature extractors, one for the dependent variable, and one for the conditioning variable. We show that under mild conditions, the features are unique up to scaling and permutation. Second, we propose the framework of independently modulated component analysis (IMCA), a new form of nonlinear ICA where the indepencence assumption is relaxed. Importantly, we show that our energy-based model can be used for the estimation of the components: the features learned are a simple and often trivial transformation of the latents.