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Christopher Leckie

17 accepted papers

2026

AudioMosaic: Contrastive Masked Audio Representation Learning

ICML 2026poster

Audio self-supervised learning (SSL) aims to learn general-purpose representations from large-scale unlabeled audio data and has achieved remarkable progress in recent years. While most prior work relies on generative reconstruction objectives, contrastive approaches remain relatively underexplored,…

Cited by 0SourceScholar
2026

Density-Aware Translation of Spurious Correlations in Zero-Shot VLMs

ICML 2026poster

Vision-Language models (VLMs), such as CLIP, achieve powerful zero-shot classification. However, their predictions remain sensitive to spurious correlations, where contextual cues dominate over semantic content. Earlier solutions typically rely on fine-tuning or prompt engineering, which either unde…

Cited by 0SourceScholar
2026

Semantic Robustness Certification for Vision-Language Models

ICML 2026poster

Vision-language models (VLMs) are now widely used in downstream tasks. However, real-world applications often expose VLMs to distribution shifts induced by semantic variation (e.g., shape, size, and style). Robustness certification determines if a model’s prediction changes when transformations are …

Cited by 0SourceScholar
2026

TRACER: Persistent Regularization for Robust Multimodal Finetuning

ICML 2026poster

Finetuning pretrained multimodal models improves in-distribution performance but often degrades out-of-distribution (OOD) robustness, a phenomenon known as catastrophic forgetting. We develop a theoretical framework for multimodal contrastive finetuning by introducing a *contrastive target matrix* t…

Cited by 0SourceScholar
2026

Toward Universal and Transferable Jailbreak Attacks on Vision-Language Models

ICLR 2026poster

Vision–language models (VLMs) extend large language models (LLMs) with vision encoders, enabling text generation conditioned on both images and text. However, this multimodal integration expands the attack surface by exposing the model to image-based jailbreaks crafted to induce harmful responses. E…

Cited by 0SourcecodeScholar
2025

Fortifying Time Series: DTW-Certified Robust Anomaly Detection

NeurIPS 2025poster

Time-series anomaly detection is critical for ensuring safety in high-stakes applications, where robustness is a fundamental requirement rather than a mere performance metric. Addressing the vulnerability of these systems to adversarial manipulation is therefore essential. Existing defenses are larg…

Cited by 0SourceScholar
2025

Open-Set Graph Anomaly Detection via Normal Structure Regularisation

ICLR 2025poster

This paper considers an important Graph Anomaly Detection (GAD) task, namely open-set GAD, which aims to train a detection model using a small number of normal and anomaly nodes (referred to as *seen anomalies*) to detect both seen anomalies and *unseen anomalies* (*i.e*., anomalies that cannot be i…

2023

Cross-Domain Graph Anomaly Detection via Anomaly-Aware Contrastive Alignment

AAAI 2023technical

Cross-domain graph anomaly detection (CD-GAD) describes the problem of detecting anomalous nodes in an unlabelled target graph using auxiliary, related source graphs with labelled anomalous and normal nodes. Although it presents a promising approach to address the notoriously high false positive iss…

2022

A Divide and Conquer Algorithm for Predict+Optimize with Non-convex Problems

AAAI 2022technical

The predict+optimize problem combines machine learning and combinatorial optimization by predicting the problem coefficients first and then using these coefficients to solve the optimization problem. While this problem can be solved in two separate stages, recent research shows end to end model…

2022

Noise-Robust Learning from Multiple Unsupervised Sources of Inferred Labels

AAAI 2022technical

Deep Neural Networks (DNNs) generally require large-scale datasets for training. Since manually obtaining clean labels for large datasets is extremely expensive, unsupervised models based on domain-specific heuristics can be used to efficiently infer the labels for such datasets. However, the labels…

Cited by 10SourcePDFScholar
2022

l∞-Robustness and Beyond: Unleashing Efficient Adversarial Training

ECCV 2022poster

"Neural networks are vulnerable to adversarial attacks: adding well-crafted, imperceptible perturbations to their input can modify their output. Adversarial training is one of the most effective approaches in training robust models against such attacks. However, it is much slower than vanilla traini…

Cited by 24SourcePDFScholar
2021

Closing the BIG-LID: An Effective Local Intrinsic Dimensionality Defense for Nonlinear Regression Poisoning

IJCAI 2021poster

Nonlinear regression, although widely used in engineering, financial and security applications for automated decision making, is known to be vulnerable to training data poisoning. Targeted poisoning attacks may cause learning algorithms to fit decision functions with poor predictive performance. Thi…

2021

Embracing Domain Differences in Fake News: Cross-domain Fake News Detection using Multi-modal Data

AAAI 2021technical

With the rapid evolution of social media, fake news has become a significant social problem, which cannot be addressed in a timely manner using manual investigation. This has motivated numerous studies on automating fake news detection. Most studies explore supervised training models with different…

Cited by 140SourcePDFScholar
2020

AdvFlow: Inconspicuous Black-box Adversarial Attacks using Normalizing Flows

NeurIPS 2020poster

Deep learning classifiers are susceptible to well-crafted, imperceptible variations of their inputs, known as adversarial attacks. In this regard, the study of powerful attack models sheds light on the sources of vulnerability in these classifiers, hopefully leading to more robust ones. In this pape…

2020

Invertible Generative Modeling using Linear Rational Splines

AISTATS 2020poster

Normalizing flows attempt to model an arbitrary probability distribution through a set of invertible mappings. These transformations are required to achieve a tractable Jacobian determinant that can be used in high-dimensional scenarios. The first normalizing flow designs used coupling layer mapping…

2015

Pattern based anomalous user detection in cognitive radio networks

ICASSP 2015accepted

Cognitive radio (CR) provides the ability to sense the range of frequencies (spectrum) that are not utilized by the incumbent user (primary user) and to opportunistically use the unoccupied spectrum in a heterogeneous environment. This can use a collaborative spectrum sensing approach to detect the…

Cited by 0SourceScholar