Vasudevan Nedumpozhimana


2026

This paper systematically evaluates LLM reliability on the complex semantic task of Natural Language Inference (NLI) in Farsi, assessing six prominent models across eight prompt variations through a multi-dimensional framework that measures accuracy, prompt sensitivity, and intra-class consistency. Our results demonstrate that prompt design—particularly the order of premise and hypothesis—significantly impacts prediction stability. Proprietary models (Claude-Opus-4, GPT-4o) exhibit superior stability and accuracy compared to open-weight alternatives. Across all models, the ’Neutral’ class emerges as the most challenging and least stable category. Crucially, we redefine model instability as a diagnostic tool for benchmark quality, demonstrating that observed disagreement often reflects valid challenges to ambiguous or erroneous gold-standard labels.

2023

The goal of this paper is to learn more about how idiomatic information is structurally encoded in embeddings, using a structural probing method. We repurpose an existing English verbal multi-word expression (MWE) dataset to suit the probing framework and perform a comparative probing study of static (GloVe) and contextual (BERT) embeddings. Our experiments indicate that both encode some idiomatic information to varying degrees, but yield conflicting evidence as to whether idiomaticity is encoded in the vector norm, leaving this an open question. We also identify some limitations of the used dataset and highlight important directions for future work in improving its suitability for a probing analysis.
Identification of mentions of medical concepts in social media text can provide useful information for caseload prediction of diseases like Covid-19 and Measles. We propose a simple model for the automatic identification of the medical concept mentions in the social media text. We validate the effectiveness of the proposed model on Twitter, Reddit, and News/Media datasets.
In the context of an epidemiological study involving multilingual social media, this paper reports on the ability of machine translation systems to preserve content relevant for a document classification task designed to determine whether the social media text is related to covid. The results indicate that machine translation does provide a feasible basis for scaling epidemiological social media surveillance to multiple languages. Moreover, a qualitative error analysis revealed that the majority of classification errors are not caused by MT errors.

2021

Sentence embeddings encode information relating to the usage of idioms in a sentence. This paper reports a set of experiments that combine a probing methodology with input masking to analyse where in a sentence this idiomatic information is taken from, and what form it takes. Our results indicate that BERT’s idiomatic key is primarily found within an idiomatic expression, but also draws on information from the surrounding context. Also, BERT can distinguish between the disruption in a sentence caused by words missing and the incongruity caused by idiomatic usage.