Education
Gaussian Process Tilted Nonparametric Density Estimation using Fisher Divergence Score Matching
Paisley, John, Zhang, Wei, Barr, Brian
We propose a nonparametric density estimator based on the Gaussian process (GP) and derive three novel closed form learning algorithms based on Fisher divergence (FD) score matching. The density estimator is formed by multiplying a base multivariate normal distribution with an exponentiated GP refinement, and so we refer to it as a GP-tilted nonparametric density. By representing the GP part of the score as a linear function using the random Fourier feature (RFF) approximation, we show that optimization can be solved in closed form for the three FD-based objectives considered. This includes the basic and noise conditional versions of the Fisher divergence, as well as an alternative to noise conditional FD models based on variational inference (VI) that we propose in this paper. For this novel learning approach, we propose an ELBO-like optimization to approximate the posterior distribution, with which we then derive a Fisher variational predictive distribution. The RFF representation of the GP, which is functionally equivalent to a single layer neural network score model with cosine activation, provides a useful linear representation of the GP for which all expectations can be solved. The Gaussian base distribution also helps with tractability of the VI approximation and ensures that our proposed density is well-defined. We demonstrate our three learning algorithms, as well as a MAP baseline algorithm, on several low dimensional density estimation problems. The closed form nature of the learning problem removes the reliance on iterative learning algorithms, making this technique particularly well-suited to big data sets, since only sufficient statistics collected from a single pass through the data is needed.
A Holiday Gift Guide: Presents for Kids
Toys, crafts, lab kits, and more for the young loved ones in your life. In theory, buying gifts for children is a snap. If they're old enough to talk, but not old enough to ignore you completely, they will likely tell you what they want. And, if your kids run in the same kinds of circles as mine, they all seem to want the same things: fidget rings, slime, a Labubu key chain, a Squishmallow, a Sephora gift card, a digital wad of Robux, a hoverboard, and maybe a puppy. The adult who strives for a more bespoke level of gift-giving--or simply to find something with no connection to screens, mirrors, or fads--risks coming off as presumptuous and pretentious.
Supplementary Materials for: Online Training Through Time for Spiking Neural Networks
A.3 Proof of Theorem 1 In this subsection, we prove Theorem 1 with Assumption 1. Assumption 1. l = 1,, N, t = 1,, T, diag null As described in Sections 4.1 and 4.2, for gradients of OTTT, we have Remark 2. The above conclusion mainly focuses on the gradients for connection weights Remark 3. Note that the gradients based on spike representation may also include small errors since A.4 Proof of Theorem 2 In this subsection, we prove Theorem 2. Theorem 2. If Assumption 1 holds, As described in Sections 4.1 and 4.2 and similar to the proof of Theorem 1, let Remark 4. The above conclusion considers the single-layer condition. It can be generalized to the multi-layer condition. Therefore, the conclusion can be directly generalized to these conditions as well. L} based on the gradient-based optimizer. For VGG network structures, we directly impose sWS on all weights. For more illustrations and other details, please directly refer to [4].