Zijun (Marshall) Zhang
Appearance

Zijun (Marshall) Zhang

I study intelligent systems where models meet the world — agents, security, and markets.

PhD researcher at the University of Melbourne studying the security of LLM-based systems under constrained external interaction.

I am supervised by Xingliang Yuan (opens in a new tab), Bang Wu (opens in a new tab), and Shangqi Lai (opens in a new tab).

Current focus

  1. Model boundary

    Security and privacy in language models.

  2. Stateful agents

    Security and reliability in AI agents.

  3. Multi-principal systems

    Security in systems with multiple interacting participants.

Selected work

Published research and independent exploration.

Published researchSTMUS 2025 workshop

When Forgetting Reveals

Can model behaviour reveal what was meant to be forgotten? I developed and evaluated a probe-based pipeline comparing original and unlearned LLMs to infer removed subjects.

Read the paper (opens in a new tab)

Independent explorationIn development

MetaArb

An independent project exploring how AI agents could take a market question through a full research cycle.

About the idea

A little background

I studied Computing and Software Systems as an undergraduate and completed a master’s in Computer Science. My PhD now focuses on the security of LLM-based systems, from individual models to agents and multi-principal systems.

Much of what interests me lives at a boundary: between model and system, prediction and action, certainty and uncertainty. I like building around those boundaries — and then testing the assumptions that hold them together.