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AFast Convoluted Story: Scaling Probabilistic Inference for Integer Arithmetic

Neural Information Processing Systems

As illustrated by the success of integer linear programming, linear integer arithmetic is a powerful tool for modelling combinatorial problems. Furthermore, the probabilistic extension of linear programming has been used to formulate problems in neurosymbolic AI. However, two key problems persist that prevent the adoption of neurosymbolic techniques beyond toy problems. First, probabilistic inference is inherently hard, #P-hard to be precise. Second, the discrete nature of integers renders the construction of meaningful gradients challenging, which is problematic for learning. In order to mitigate these issues, we formulate linear arithmetic over integer-valued random variables as tensor manipulations that can be implemented in a straightforward fashion using modern deep learning libraries. At the core of our formulation lies the observation that the addition of two integer-valued random variables can be performed by adapting the fast Fourier transform to probabilities in the log-domain. By relying on tensor operations we obtain a differentiable data structure, which unlocks, virtually for free, gradient-based learning. In our experimental validation we show that tensorising probabilistic linear integer arithmetic and leveraging the fast Fourier transform allows us to push the state of the art by several orders of magnitude in terms of inference and learning times.





On Learning Latent Models with Multi-Instance Weak Supervision

Neural Information Processing Systems

We consider a weakly supervised learning scenario where the supervision signal is generated by a transition function σ of labels associated with multiple input instances. We formulate this problem as multi-instance Partial Label Learning (multi-instance PLL). Our problem is an extension to the standard PLL problem and is met in different fields, including latent structural learning and neuro-symbolic integration. Despite the existence of many learning techniques, limited theoretical analysis has been dedicated to this problem. In this paper, we provide the first theoretical study of multi-instance PLL with possibly an unknown transition σ.


VAEL: Bridging Variational Autoencoders and Probabilistic Logic Programming

Neural Information Processing Systems

Besides standard latent subsymbolic variables, our model exploits a probabilistic logic program to define a further structured representation, which is used for logical reasoning. The entire process is end-to-end differentiable. Once trained, VAEL can solve new unseen generation tasks by (i) leveraging the previously acquired knowledge encoded in the neural component and (ii) exploiting new logical programs on the structured latent space. Our experiments provide support on the benefits of this neuro-symbolic integration both in terms of task generalization and data efficiency. To the best of our knowledge, this work is the first to propose a general-purpose end-to-end framework integrating probabilistic logic programming into a deep generative model.



Appendix 1 Interpretation using rank-1 Nyström approximation

Neural Information Processing Systems

The bound in Equation 5 of the main paper can be interpreted using a rank-1 Nyström approximation for f(xt,xt). By holding w fixed and maximizing for q in the right hand side of Equation 5, we get q = f(w,w) P t ytf(xt,w) where f(w,w) indicates the pseudo-inverse.1 Typically the weight vector w, often called a "landmark", used in the Nyström approximation is set either by setting it to a random input or by more sophisticated schemes like setting it with KMeans. In our case, we are directly optimizing the landmarks via Equation 6 in the main paper. To our knowledge the only other work to do this was performed in Fu [2014]. The code used in the main training loop of our algorithm is shown in Figure 1.