Estrid He
Author directoryAlso published as: Jiayuan He
2026
Twin Worlds: Equivariance-Based Abstention for Evidence-Grounded Reasoning
Vy Nguyen | Ziqi Xu | Jeffrey Chan | Estrid He | Feng Xia | Renqiang Luo | Erik Cambria | Xiuzhen Zhang
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Vy Nguyen | Ziqi Xu | Jeffrey Chan | Estrid He | Feng Xia | Renqiang Luo | Erik Cambria | Xiuzhen Zhang
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Knowledge-intensive reasoning requires Large Language Models (LLMs) to ground answers in provided evidence. When evidence is insufficient, it is desirable that models abstain rather than confidently generating unsupported answers. Existing abstention methods rely on uncertainty estimation or evidence sufficiency checks, but neither tests whether the reasoning process for generation, driven by the interaction of provided evidence and the model’s internal memory parameters, is actually grounded in the evidence. A key contributing factor is that entity mentions in context activate memorised associations, causing models to generate plausible responses ungrounded in evidence. We propose Twin Worlds (TW), a framework for improving reliability in knowledge-intensive reasoning through equivariance-based abstention: unlike invariance, which requires outputs to remain unchanged, equivariance requires outputs to transform correspondingly under entity substitutions. A model grounded in the evidence should produce answers that shift consistently when entities are substituted while their relations are preserved. TW constructs multiple worlds via typed substitutions of the original input that preserve relational structure while reducing parametric priors, and uses equivariance violations as an abstention signal. Across four benchmarks and three model backbones, TW identifies when answers are not reliably grounded in the provided evidence and outperforms uncertainty- and sufficiency-based baselines.
Decouple to Forget: Semantic Mediation for Sensitive Unlearning in Large Language Models
Jingyue Cong | Andy Song | Yang Yu | Tabinda Sarwar | Xinshu Li | Ziqi Xu | Xun Yi | Ke Wang | Bo Han | Estrid He
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Jingyue Cong | Andy Song | Yang Yu | Tabinda Sarwar | Xinshu Li | Ziqi Xu | Xun Yi | Ke Wang | Bo Han | Estrid He
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Machine unlearning for large language models seeks to remove specified knowledge while preserving general capability, yet current methods often treat an entire response as the unit of forgetting. This coarse granularity causes unnecessary utility loss when the forget target is only a small set of sensitive facts embedded within otherwise benign explanations. In this paper, we introduce Decouple to Forget (D2F), a targeted unlearning method based on causal mediation that separates sensitive factual content from non-sensitive meaning and surface expression. For each example to be forgotten, D2F extracts a fact-level “mediator” representation from the answer, identifies which parts are sensitive, and removes only those parts while leaving the rest of the structure intact. We then generate counterfactual answers grounded in this mediator that preserve non-sensitive content but exclude sensitive facts, employing preference-based contrastive optimization to reduce the likelihood of information leakage while maintaining helpfulness and fluency. Experiments across various benchmark datasets show that D2F achieves a better balance between forgetting and retention than strong baseline methods. Our code is available at https://anonymous.4open.science/r/D2F-D596/.
GraphProfiler: Source-Linked Sensitive Attribute Inference via Personal Knowledge Graphs
Ahmed Sohair Khan | Estrid He | Chenglong Ma | Monica Wachowicz | Elham Naghizade
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Ahmed Sohair Khan | Estrid He | Chenglong Ma | Monica Wachowicz | Elham Naghizade
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Sensitive attributes such as age, income, and occupation can be inferred from user-generated content by aggregating indirect cues across many ordinary posts. LLM-based profilers can perform this aggregation automatically and with high accuracy, which makes large-scale personal attribute inference a major privacy threat. Existing LLM-based profilers, however, offer limited insight into which specific posts, concepts, and relationships made an inference possible, which is key to targeted privacy mitigation, i.e., redacting or rewriting only the few posts that actually leak an attribute, rather than perturbing entire histories. We introduce GraphProfiler, an auditable LLM-based profiler that represents each user’s post history as a source-linked personal knowledge graph where nodes and edges trace back to the originating post and resolves attribute predictions to cited graph records and source texts. GraphProfiler reaches 86.7% attack success rate on the eight-attribute SynthPAI benchmark, within two points of strong text-only baselines, and 84.6% on PANDORA, while citing supporting evidence for over 98% of predictions. Our controlled ablation experiments provide evidence that the cited posts contribute to attack success, as removing them reduces the attack success rate substantially more than removing an equal number of random posts.
Graph-Guided Selective Unlearning for Language Models: Controlling Support Routes Beyond Forget Seeds
Waqas Khan | Tabinda Sarwar | Jingyue Cong | Xun Yi | Estrid He
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track
Waqas Khan | Tabinda Sarwar | Jingyue Cong | Xun Yi | Estrid He
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track
Enterprises fine-tune language models on proprietary data that may later require removal due to privacy, contractual, or compliance obligations. Selective unlearning removes requested knowledge while preserving model utility, offering a practical alternative to full retraining, but existing methods treat the explicitly identified forget examples as the complete deletion scope. This is insufficient when target knowledge remains recoverable through paraphrases, aliases, or neighboring training examples. We propose GraphSU, a graph-guided controller that expands the deletion scope beyond forget seeds by constructing a weighted support-route graph, propagating deletion pressure through it, and applying graded forgetting strengths to high-risk neighbors. On TOFU and PISTOL with GPT-2 Medium and Llama-3.2-3B-Instruct, GraphSU achieves the lowest utility-feasible soft leakage across all deletion settings, reducing leakage by up to 49.5 percentage points over a matched seed-only baseline, demonstrating that effective enterprise unlearning requires controlling support routes, not just forget seeds.
LatentRiskBench: Measuring State-Dependent Risks in Enterprise Agents
Jingyue Cong | Estrid He | Zhuang Li | Li Shen | Nan Wu | Yameng Peng | Xinshu Li | Andy Song
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track
Jingyue Cong | Estrid He | Zhuang Li | Li Shen | Nan Wu | Yameng Peng | Xinshu Li | Andy Song
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track
Enterprise agents face safety risks that cannot be determined from individual actions alone. Existing safety benchmarks largely evaluate action-local risks, overlooking failures whose safety depends on workflow state. In such state-dependent risks, the same action may be safe in one context but violate policy in another. Hence, we introduce LatentRiskBench for evaluating such state-dependent risks in enterprise settings. It pairs risky trajectories with benign counterparts that share the same terminal action but differ in latent policy-relevant states, requiring models to reconstruct workflow context rather than rely on action-level cues. We also introduce new metrics for state-dependent risk evaluation, including a suite of residual risk (RR) measures. Experiments on the benchmark show that action-level evaluation detects only 0.09 of state-dependent violations, whereas state-level evaluation reaches 0.96. Existing guardrail methods largely overlook such risks unless they are explicitly applied to workflow states. Case studies on a commercial deployed scenario further show that the safety metrics embedded in the benchmark provide a more realistic measure of safety for enterprise agents.
2024
Principles from Clinical Research for NLP Model Generalization
Aparna Elangovan | Jiayuan He | Yuan Li | Karin Verspoor
Proceedings of the 2024 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies (Volume 1: Long Papers)
Aparna Elangovan | Jiayuan He | Yuan Li | Karin Verspoor
Proceedings of the 2024 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies (Volume 1: Long Papers)
The NLP community typically relies on performance of a model on a held-out test set to assess generalization. Performance drops observed in datasets outside of official test sets are generally attributed to “out-of-distribution” effects. Here, we explore the foundations of generalizability and study the factors that affect it, articulating lessons from clinical studies. In clinical research, generalizability is an act of reasoning that depends on (a) internal validity of experiments to ensure controlled measurement of cause and effect, and (b) external validity or transportability of the results to the wider population. We demonstrate how learning spurious correlations, such as the distance between entities in relation extraction tasks, can affect a model’s internal validity and in turn adversely impact generalization. We, therefore, present the need to ensure internal validity when building machine learning models in NLP. Our recommendations also apply to generative large language models, as they are known to be sensitive to even minor semantic preserving alterations. We also propose adapting the idea of matching in randomized controlled trials and observational studies to NLP evaluation to measure causation.
2023
Effects of Human Adversarial and Affable Samples on BERT Generalization
Aparna Elangovan | Estrid He | Yuan Li | Karin Verspoor
Findings of the Association for Computational Linguistics: EMNLP 2023
Aparna Elangovan | Estrid He | Yuan Li | Karin Verspoor
Findings of the Association for Computational Linguistics: EMNLP 2023
BERT-based models have had strong performance on leaderboards, yet have been demonstrably worse in real-world settings requiring generalization. Limited quantities of training data is considered a key impediment to achieving generalizability in machine learning. In this paper, we examine the impact of training data quality, not quantity, on a model’s generalizability. We consider two characteristics of training data: the portion of human-adversarial (h-adversarial), i.e. sample pairs with seemingly minor differences but different ground-truth labels, and human-affable (h-affable) training samples, i.e. sample pairs with minor differences but the same ground-truth label. We find that for a fixed size of training samples, as a rule of thumb, having 10-30% h-adversarial instances improves the precision, and therefore F1, by up to 20 points in the tasks of text classification and relation extraction. Increasing h-adversarials beyond this range can result in performance plateaus or even degradation. In contrast, h-affables may not contribute to a model’s generalizability and may even degrade generalization performance.
2021
ChEMU-Ref: A Corpus for Modeling Anaphora Resolution in the Chemical Domain
Biaoyan Fang | Christian Druckenbrodt | Saber A Akhondi | Jiayuan He | Timothy Baldwin | Karin Verspoor
Proceedings of the 16th Conference of the European Chapter of the Association for Computational Linguistics: Main Volume
Biaoyan Fang | Christian Druckenbrodt | Saber A Akhondi | Jiayuan He | Timothy Baldwin | Karin Verspoor
Proceedings of the 16th Conference of the European Chapter of the Association for Computational Linguistics: Main Volume
Chemical patents contain rich coreference and bridging links, which are the target of this research. Specially, we introduce a novel annotation scheme, based on which we create the ChEMU-Ref dataset from reaction description snippets in English-language chemical patents. We propose a neural approach to anaphora resolution, which we show to achieve strong results, especially when jointly trained over coreference and bridging links.
Memorization vs. Generalization : Quantifying Data Leakage in NLP Performance Evaluation
Aparna Elangovan | Jiayuan He | Karin Verspoor
Proceedings of the 16th Conference of the European Chapter of the Association for Computational Linguistics: Main Volume
Aparna Elangovan | Jiayuan He | Karin Verspoor
Proceedings of the 16th Conference of the European Chapter of the Association for Computational Linguistics: Main Volume
Public datasets are often used to evaluate the efficacy and generalizability of state-of-the-art methods for many tasks in natural language processing (NLP). However, the presence of overlap between the train and test datasets can lead to inflated results, inadvertently evaluating the model’s ability to memorize and interpreting it as the ability to generalize. In addition, such data sets may not provide an effective indicator of the performance of these methods in real world scenarios. We identify leakage of training data into test data on several publicly available datasets used to evaluate NLP tasks, including named entity recognition and relation extraction, and study them to assess the impact of that leakage on the model’s ability to memorize versus generalize.
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Co-authors
- Karin Verspoor 4
- Jingyue Cong 3
- Aparna Elangovan 3
- Xinshu Li 2
- Yuan Li 2
- Tabinda Sarwar 2
- Andy Song 2
- Ziqi Xu 2
- Xun Yi 2
- Saber A. Akhondi 1
- Timothy Baldwin 1
- Erik Cambria 1
- Jeffrey Chan 1
- Christian Druckenbrodt 1
- Biaoyan Fang 1
- Bo Han 1
- Ahmed Sohair Khan 1
- Waqas Khan 1
- Zhuang Li 1
- Renqiang Luo 1
- Chenglong Ma 1
- Elham Naghizade 1
- Vy Nguyen 1
- Yameng Peng 1
- Li Shen 1
- Monica Wachowicz 1
- Ke Wang 1
- Nan Wu 1
- Feng Xia 1
- Yang Yu 1
- Xiuzhen (Jenny) Zhang 1