Plenary Talks

Professor Li Chen

School of Electronics & Information Engineering,
Sun Yat-Sen University, China

Title: Algebra Remains a Cradle for Improving Codes

Abstract: The success of modern codes demonstrates the importance of probabilistic decoding which is a tunnel of utilizing soft information for data recovery. It can overshadow the role of conventional algebra such as minimum distance of a code. However, probabilistic decoding is effective when codeword length is large. Short-to-medium length (SML) codes may play an important role for scenarios that demand both high reliability and low latency or even power consumption. For SML codes, algebraic codes and structures are important for gaining error-correction competency. This talk will show grouping algebraic component codes through an algebraic structure enables interplay between their decoding, compensating their naturally small minimum distances. Two cases in recent coding practice will be shown, U-UV codes and GII codes. U-UV codes couple component codes in Plotkin structure. Empowered by soft decoding, they can be useful for 6G networks. GII codes visualize linear combinations of component codes in a nesting codebook paradigm in tackling richer error patterns. They can be useful for scenarios with scarce soft information, such as optical and chip communications.

Professor Debbie Leung

Institute for Quantum Computing and
Department of Combinatorics & Optimization,
University of Waterloo, Canada

Title: Non-additivity of quantum channel capacity

Abstract: The best rate for a noisy communication channel to transmit data nearly perfectly is called the capacity. Surprisingly, the capacity for a classical channel to transmit classical data has a simple expression, with consequences such as, there is only one way for a channel to have zero capacity, and there is no capacity gain by coding for two different channels used jointly. This talk will feature notable differences for the quantum setting when we consider the capacity for a quantum channel to transmit quantum data. We will further examine a family of channels called platypus channels displaying super-additivity of quantum capacity when used jointly with a quantum erasure channel, and other forms of superadditivity when used jointly with some generic channels. Our results show that super-additivity is much more prevalent than previously thought. Joint work with Felix Leditzky, Vikesh Siddhu, Graeme Smith, and John Smolin

Professor Alon Orlitsky
Information Theory and Applications Center,
University of California San Diego, USA

Title: Towards improving LLM English perplexity

Abstract: Over the past decade there has been a significant effort to improve Large Language Models (LLMs) performance. The fundamental aspect of training LLMs is next-word prediction over a large corpus as measured by the resulting perplexity. Models with lower perplexity consistently improve performance across a variety of downstream tasks including reasoning, coding, and question-answering. In this talk we review existing perplexity-reduction approaches, and show how information-theoretic, syntactical, statistical, and diversification-based techniques may help further reduce the LLM perplexity for the common WikiText-103 benchmark.

Professor Wei Yu

Electrical and Computer Engineering Department,
University of Toronto, Canada

Title: Surprises in Network Information Theory

Abstract: Information theory aims to characterize the fundamental limits of compressing, representation, and transmission of information in communication networks. For instance, to identify one of N distinct objects, log(N) bits of information are needed. Moreover, the maximum rate of information transmission through a noisy channel is approximately the logarithm of the signal-to-noise ratio. In this talk, we explore several unusual scenarios where information theoretical analyses yield surprising results. We ask the following questions: 1) Is it possible to transmit information through a noisy channel at a strictly positive rate using only infinitesimal amount of transmit power? 2) For transmitting independent messages to a subset of K active devices among a large pool of N devices, is it possible to avoid using an address field of size log(N) bits to identify the intended recipient of each message? The answers to both questions are surprisingly, yes! We discuss the implications of these results to cooperative communications and to massive random access in wireless networking.