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Prathosh AP

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9 papers

1 author row

TMLR Journal 2026 Journal Article

An Efficient Subset Selection Strategy Using Text-Guided Data Attribution to Mitigate Simplicity Bias

Kumar Shubham
Pranav Sastry
Prathosh AP

The effectiveness of deep learning models heavily relies on the quality and diversity of their training data. However, datasets collected from different sources often introduce simplicity biases, where a models rely on easily learnable but non-predictive (spurious) features for its predictions. While existing debiasing techniques focus on model robustness, they leave the data untouched. However, as data becomes increasingly valuable, identifying and mitigating bias directly at the data level has become increasingly important. Recently, data attribution has emerged as a promising tool for uncovering issues in training data, yet its vulnerability to simplicity bias has received limited attention. In this work, we propose a novel data deletion framework that combines Neural Tangent Kernel (NTK)-based data attribution with textual descriptions of bias to identify and remove training samples that do not significantly affect model performance. We first demonstrate that NTK-based data attribution methods can themselves be influenced by spurious features. Subsequently, to mitigate this, we use available metadata or, when unavailable, a vision-language model to annotate a small validation set and extract a textual description of the bias. Based on this description and the attribution score, we identify the subset of training data that are semantically aligned with the spurious feature and affect the generalization of the model. Removing these samples from the training dataset and training model on the new subset improves the average and worst-group accuracy of the model, outperforming existing attribution-based baselines.

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TMLR Journal 2026 Journal Article

Unlearning in Diffusion models under Data Constraints: A Variational Inference Approach

Subhodip Panda
Varun M S
Shreyans Jain
Sarthak Kumar Maharana
Prathosh AP

For a responsible and safe deployment of diffusion models in various domains, regulating the generated outputs from these models is desirable because such models could generate undesired, violent, and obscene outputs. To tackle this problem, recent works use machine unlearning methodology to forget training data points containing these undesired features from pre-trained generative models. However, these methods proved to be ineffective in data-constrained settings where the whole training dataset is inaccessible. Thus, the principal objective of this work is to propose a machine unlearning methodology that can prevent the generation of outputs containing undesired features from a pre-trained diffusion model in such a data-constrained setting. Our proposed method, termed as Variational Diffusion Unlearning (**VDU**), is a computationally efficient method that only requires access to a subset of training data containing undesired features. Our approach is inspired by the variational inference framework with the objective of minimizing a loss function consisting of two terms: *plasticity inducer* and *stability regularizer*. *Plasticity inducer* reduces the log-likelihood of the undesired training data points, while the *stability regularizer*, essential for preventing loss of image generation quality, regularizes the model in parameter space. We validate the effectiveness of our method through comprehensive experiments for both class unlearning and feature unlearning. For class unlearning, we unlearn some user-identified classes from MNIST, CIFAR-10, and tinyImageNet datasets from a pre-trained unconditional denoising diffusion probabilistic model (DDPM). Similarly, for feature unlearning, we unlearn the generation of certain high-level features from a pre-trained Stable Diffusion model.

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TMLR Journal 2025 Journal Article

Adapt then Unlearn: Exploring Parameter Space Semantics for Unlearning in Generative Adversarial Networks

Piyush Tiwary
Atri Guha
Subhodip Panda
Prathosh AP

Owing to the growing concerns about privacy and regulatory compliance, it is desirable to regulate the output of generative models. To that end, the objective of this work is to prevent the generation of outputs containing undesired features from a pre-trained Generative Adversarial Network (GAN) where the underlying training data set is inaccessible. Our approach is inspired by the observation that the parameter space of GANs exhibits meaningful directions that can be leveraged to suppress specific undesired features. However, such directions usually result in the degradation of the quality of generated samples. Our proposed two-stage method, known as 'Adapt-then-Unlearn,' excels at unlearning such undesirable features while also maintaining the quality of generated samples. In the initial stage, we adapt a pre-trained GAN on a set of negative samples (containing undesired features) provided by the user. Subsequently, we train the original pre-trained GAN using positive samples, along with a repulsion regularizer. This regularizer encourages the learned model parameters to move away from the parameters of the adapted model (first stage) while not degrading the generation quality. We provide theoretical insights into the proposed method. To the best of our knowledge, our approach stands as the first method addressing unlearning within the realm of high-fidelity GANs (such as StyleGAN). We validate the effectiveness of our method through comprehensive experiments, encompassing both class-level unlearning on the MNIST and AFHQ dataset and feature-level unlearning tasks on the CelebA-HQ dataset. Our code and implementation is available at: https://github.com/atriguha/Adapt_Unlearn.

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TMLR Journal 2025 Journal Article

GOTHAM: Graph Class Incremental Learning Framework under Weak Supervision

Aditya Hemant Shahane
Prathosh AP
Sandeep Kumar

Graphs are growing rapidly and so are the number of different categories associated with it. Applications like e-commerce, healthcare, recommendation systems, and various social media platforms are rapidly moving towards graph representation of data due to their ability to capture both structural and attribute information. One crucial task in graph analysis is node classification, where unlabeled nodes are categorized into predefined classes. In practice, novel classes appear incrementally sometimes with just a few labels (seen classes) or even without any labels (unseen classes), either because they are new or haven't been explored much. Traditional methods assume abundant labeled data for training, which isn't always feasible. We investigate a broader objective: Graph Class Incremental Learning under Weak Supervision (GCL), addressing this challenge by meta-training on base classes with limited labeled instances. During the incremental streams, novel classes can have few-shot or zero-shot representation. Our proposed framework GOTHAM efficiently accommodates these unlabeled nodes by finding the closest prototype representation, serving as class representatives in the attribute space. For Text-Attributed Graphs (TAGs), our framework additionally incorporates semantic information to enhance the representation. By employing teacher-student knowledge distillation to mitigate forgetting, GOTHAM achieves promising results across various tasks. Experiments on datasets such as Cora-ML, Amazon, and OBGN-Arxiv showcase the effectiveness of our approach in handling evolving graph data under limited supervision.

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TMLR Journal 2025 Journal Article

Lifelong Learning in StyleGAN through Latent Subspaces

Adarsh Kappiyath
ANMOL GARG
Ramya Hebbalaguppe
Prathosh AP

StyleGAN is one of the most versatile generative models that have emerged in recent times. However, when it is trained continually on a stream of data (potentially previously unseen distributions), it tends to forget the distribution it has learned, as is the case with any other generative model, due to catastrophic forgetting. Recent studies have shown that the latent space of StyleGAN is very versatile, as data from a variety of distributions can be inverted onto it. In this paper, we propose StyleCL, a method that leverages this property to enable lifelong learning in StyleGAN without forgetting. Specifically, given a StyleGAN trained on a certain task (dataset), we propose to learn a latent subspace characterized by a set of dictionary vectors in its latent space, one for each novel, unseen task (or dataset). We also learn a relatively small set of parameters (feature adaptors) in the weight space to complement the dictionary learning in the latent space. Furthermore, we introduce a method that utilizes the similarity between tasks to effectively reuse the feature adaptor parameters from the previous tasks, aiding in the learning process for the current task at hand. Our approach guarantees that the parameters from previous tasks are reused only if they contribute to a beneficial forward transfer of knowledge. Remarkably, StyleCL avoids catastrophic forgetting because the set of dictionary and the feature adaptor parameters are unique for each task. We demonstrate that our method, StyleCL, achieves better generation quality on multiple datasets with significantly fewer additional parameters per task compared to previous methods. This is a consequence of learning task-specific dictionaries in the latent space, which has a much lower dimensionality compared to the weight space. Code for this work is available at \href{https://github.com/kadarsh22/StyleCL}{link}

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AAAI Conference 2024 Conference Paper

Fusing Conditional Submodular GAN and Programmatic Weak Supervision

Kumar Shubham
Pranav Sastry
Prathosh AP

Programmatic Weak Supervision (PWS) and generative models serve as crucial tools that enable researchers to maximize the utility of existing datasets without resorting to laborious data gathering and manual annotation processes. PWS uses various weak supervision techniques to estimate the underlying class labels of data, while generative models primarily concentrate on sampling from the underlying distribution of the given dataset. Although these methods have the potential to complement each other, they have mostly been studied independently. Recently, WSGAN proposed a mechanism to fuse these two models. Their approach utilizes the discrete latent factors of InfoGAN for the training of the label models and leverages the class-dependent information of the label models to generate images of specific classes. However, the disentangled latent factor learned by the InfoGAN may not necessarily be class specific and hence could potentially affect the label model's accuracy. Moreover, the prediction of the label model is often noisy in nature and can have a detrimental impact on the quality of images generated by GAN. In our work, we address these challenges by (i) implementing a noise-aware classifier using the pseudo labels generated by the label model, (ii) utilizing the prediction of the noise-aware classifier for training the label model as well as generation of class-conditioned images. Additionally, We also investigate the effect of training the classifier with a subset of the dataset within a defined uncertainty budget on pseudo labels. We accomplish this by formalizing the subset selection problem as submodular maximization with a knapsack constraint on the entropy of pseudo labels. We conduct experiments on multiple datasets and demonstrate the efficacy of our methods on several tasks vis-a-vis the current state-of-the-art methods. Our implementation is available at https://github.com/kyrs/subpws-gan

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TMLR Journal 2024 Journal Article

Teacher-Guided Graph Contrastive Learning

Jay Nandy
Arnab Kumar Mondal
Manohar Kaul
Prathosh AP

State-of-the-art self-supervised representation learning methods for Graphs are typically based on contrastive learning (CL) principles. These CL objective functions can be posed as a supervised discriminative task using *'hard'* labels that consider any minor augmented pairs of graphs as 'equally positive'. However, such a notion of 'equal' pairs is incorrect for graphs as even a smaller 'discrete' perturbation may lead to large semantic changes that should be carefully encapsulated within the learned representations. This paper proposes a novel CL framework for GNNs, called *Teacher-guided Graph Contrastive Learning (TGCL)*, that incorporates 'soft' pseudo-labels to facilitate a more regularized discrimination. In particular, we propose a teacher-student framework where the student learns the representation by distilling the teacher's perception. Our TGCL framework can be adapted to existing CL methods to enhance their performance. Our empirical findings validate these claims on both inductive and transductive settings across diverse downstream tasks, including molecular graphs and social networks. Our experiments on benchmark datasets demonstrate that our framework consistently improves the average AUROC scores for molecules' property prediction and social network link prediction. Our code is available at: https://github.com/jayjaynandy/TGCL.

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AAAI Conference 2023 Conference Paper

Adaptive Mixing of Auxiliary Losses in Supervised Learning

Durga Sivasubramanian
Ayush Maheshwari
Prathosh AP
Pradeep Shenoy
Ganesh Ramakrishnan

In many supervised learning scenarios, auxiliary losses are used in order to introduce additional information or constraints into the supervised learning objective. For instance, knowledge distillation aims to mimic outputs of a powerful teacher model; similarly, in rule-based approaches, weak labeling information is provided by labeling functions which may be noisy rule-based approximations to true labels. We tackle the problem of learning to combine these losses in a principled manner. Our proposal, AMAL, uses a bi-level optimization criterion on validation data to learn optimal mixing weights, at an instance-level, over the training data. We describe a meta-learning approach towards solving this bi-level objective, and show how it can be applied to different scenarios in supervised learning. Experiments in a number of knowledge distillation and rule denoising domains show that AMAL provides noticeable gains over competitive baselines in those domains. We empirically analyze our method and share insights into the mechanisms through which it provides performance gains. The code for AMAL is at: https://github.com/durgas16/AMAL.git.

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AAAI Conference 2020 Conference Paper

Guided Weak Supervision for Action Recognition with Scarce Data to Assess Skills of Children with Autism

Prashant Pandey
Prathosh AP
Manu Kohli
Josh Pritchard

Diagnostic and intervention methodologies for skill assessment of autism typically requires a clinician repetitively initiating several stimuli and recording the child’s response. In this paper, we propose to automate the response measurement through video recording of the scene following the use of Deep Neural models for human action recognition from videos. However, supervised learning of neural networks demand large amounts of annotated data that is hard to come by. This issue is addressed by leveraging the ‘similarities’ between the action categories in publicly available large-scale video action (source) datasets and the dataset of interest. A technique called Guided Weak Supervision is proposed, where every class in the target data is matched to a class in the source data using the principle of posterior likelihood maximization. Subsequently, classiﬁer on the target data is re-trained by augmenting samples from the matched source classes, along with a new loss encouraging inter-class separability. The proposed method is evaluated on two skill assessment autism datasets, SSBD (Sundar Rajagopalan, Dhall, and Goecke 2013) and a real world Autism dataset comprising 37 children of different ages and ethnicity who are diagnosed with autism. Our proposed method is found to improve the performance of the state-of-the-art multi-class human action recognition models in-spite of supervision with scarce data.

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