Search Results for author: James Townsend

Found 13 papers, 12 papers with code

Random Edge Coding: One-Shot Bits-Back Coding of Large Labeled Graphs

1 code implementation16 May 2023 Daniel Severo, James Townsend, Ashish Khisti, Alireza Makhzani

We present a one-shot method for compressing large labeled graphs called Random Edge Coding.

Verified Reversible Programming for Verified Lossless Compression

1 code implementation2 Nov 2022 James Townsend, Jan-Willem van de Meent

Agda supports formal verification of program properties, and the compiler for our reversible language (which is implemented as an Agda macro), produces not just an encoder/decoder pair of functions but also a proof that they are inverse to one another.

Parallel Neural Local Lossless Compression

2 code implementations13 Jan 2022 Mingtian Zhang, James Townsend, Ning Kang, David Barber

The recently proposed Neural Local Lossless Compression (NeLLoC), which is based on a local autoregressive model, has achieved state-of-the-art (SOTA) out-of-distribution (OOD) generalization performance in the image compression task.

Image Compression

Adaptive Optimization with Examplewise Gradients

1 code implementation30 Nov 2021 Julius Kunze, James Townsend, David Barber

We propose a new, more general approach to the design of stochastic gradient-based optimization methods for machine learning.

BIG-bench Machine Learning

Compressing Multisets with Large Alphabets using Bits-Back Coding

1 code implementation15 Jul 2021 Daniel Severo, James Townsend, Ashish Khisti, Alireza Makhzani, Karen Ullrich

Current methods which compress multisets at an optimal rate have computational complexity that scales linearly with alphabet size, making them too slow to be practical in many real-world settings.

Lossless Compression with Latent Variable Models

1 code implementation21 Apr 2021 James Townsend

We develop a simple and elegant method for lossless compression using latent variable models, which we call 'bits back with asymmetric numeral systems' (BB-ANS).

Improving Lossless Compression Rates via Monte Carlo Bits-Back Coding

1 code implementation ICLR Workshop Neural_Compression 2021 Yangjun Ruan, Karen Ullrich, Daniel Severo, James Townsend, Ashish Khisti, Arnaud Doucet, Alireza Makhzani, Chris J. Maddison

Naively applied, our schemes would require more initial bits than the standard bits-back coder, but we show how to drastically reduce this additional cost with couplings in the latent space.

Data Compression

A tutorial on the range variant of asymmetric numeral systems

1 code implementation24 Jan 2020 James Townsend

This paper is intended to be an accessible introduction to the range variant of Asymmetric Numeral Systems (rANS).

HiLLoC: Lossless Image Compression with Hierarchical Latent Variable Models

1 code implementation ICLR 2020 James Townsend, Thomas Bird, Julius Kunze, David Barber

We make the following striking observation: fully convolutional VAE models trained on 32x32 ImageNet can generalize well, not just to 64x64 but also to far larger photographs, with no changes to the model.

Image Compression

Pymanopt: A Python Toolbox for Optimization on Manifolds using Automatic Differentiation

1 code implementation10 Mar 2016 James Townsend, Niklas Koep, Sebastian Weichwald

Optimization on manifolds is a class of methods for optimization of an objective function, subject to constraints which are smooth, in the sense that the set of points which satisfy the constraints admits the structure of a differentiable manifold.

Riemannian optimization

The VC-Dimension of Similarity Hypotheses Spaces

no code implementations25 Feb 2015 Mark Herbster, Paul Rubenstein, James Townsend

Given a set $X$ and a function $h:X\longrightarrow\{0, 1\}$ which labels each element of $X$ with either $0$ or $1$, we may define a function $h^{(s)}$ to measure the similarity of pairs of points in $X$ according to $h$.

PAC learning

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