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Publications
LIBS-Raman Multimodal Architecture for Automated Lunar Prospecting
Recent advancements in vision-language models (VLMs) have been driven by contrastive models like CLIP which learn to associate visual inform… (voir plus)ation with their corresponding text descriptions. However, these models have limitations in understanding complex compositional scenes involving multiple objects and their spatial relationships. To address these challenges, we propose a novel approach that diverges from traditional data-centric methods of enhancing model performance with hard negatives examples. Our work instead focuses on integrating sufficient inductive biases into pre-trained CLIP-like models to improve their compositional understanding without using additional data annotations. We introduce a binding module that connects a scene graph of the text with an induced graph-like representation of the image, facilitating a structured similarity assessment. We also leverage relationships as text-conditioned visual constraints, thereby capturing the intricate interactions between objects and their contextual relationships more effectively. Our resulting model (OC-CLIP) not only enhances the performance of CLIP in multi-object compositional understanding but also paves the way for more accurate and efficient image-text matching in complex scenes.
Recent trends of larger model and larger datasets require huge amounts of computational resources, making distributed deep learning essentia… (voir plus)l. Data parallelism is a common approach to speed up training, but it often involves frequent communication between workers, which can be a bottleneck. In this work, we propose a method called Pseudo-Asynchronous Local SGD (PALSGD) to improve the efficiency of data-parallel training. PALSGD is a novel extension of LocalSGD (SU Stich, 2018), designed to further reduce communication frequency by introducing a pseudo-synchronization mechanism. PALSGD allows the use of longer synchronization intervals compared to standard LocalSGD. Despite the reduced communication frequency, the pseudo-synchronization approach ensures that model consistency is maintained, leading to performance results comparable to those achieved with more frequent synchronization. Furthermore, we provide a theoretical analysis of PALSGD, establishing its convergence and deriving its convergence rate. This analysis offers insights into the algorithm's behavior and performance guarantees. We evaluated PALSGD on CIFAR-10 using a CNN and GPT-NEO on TinyStories. Our results show that PALSGD achieves better performance in less time compared to existing methods like distributed data parallel (DDP), Local SGD and DiLoCo (Douillard et al. 2023).
Neural networks often learn simple explanations that fit the majority of the data while memorizing exceptions that deviate from these explan… (voir plus)ations. This leads to poor generalization when the learned explanations are spurious. In this work, we formalize
Performative prediction is a framework accounting for the shift in the data distribution induced by the prediction of a model deployed in th… (voir plus)e real world. Ensuring rapid convergence to a stable solution where the data distribution remains the same after the model deployment is crucial, especially in evolving environments. This paper extends the Repeated Risk Minimization (RRM) framework by utilizing historical datasets from previous retraining snapshots, yielding a class of algorithms that we call Affine Risk Minimizers and enabling convergence to a performatively stable point for a broader class of problems. We introduce a new upper bound for methods that use only the final iteration of the dataset and prove for the first time the tightness of both this new bound and the previous existing bounds within the same regime. We also prove that utilizing historical datasets can surpass the lower bound for last iterate RRM, and empirically observe faster convergence to the stable point on various performative prediction benchmarks. We offer at the same time the first lower bound analysis for RRM within the class of Affine Risk Minimizers, quantifying the potential improvements in convergence speed that could be achieved with other variants in our framework.
Linear mode connectivity (LMC) has become a topic of great interest in recent years. It has been empirically demonstrated that popular deep … (voir plus)learning models trained from different initializations exhibit linear model connectivity up to permutation. Based on this, several approaches for finding a permutation of the model's features or weights have been proposed leading to several popular methods for model merging. These methods enable the simple averaging of two models to create a new high-performance model. However, besides accuracy, the properties of these models and their relationships to the representations of the models they derive from are poorly understood.
In this work, we study the inner mechanisms behind LMC in model merging through the lens of classic feature visualization methods. Focusing on convolutional neural networks (CNNs) we make several observations that shed light on the underlying mechanisms of model merging by permute and average.
Sparse autoencoders (SAEs) have been central to the effort of finding interpretable and disentangled directions of representation spaces in … (voir plus)neural networks, in both image and text domains. While the efficacy and pitfalls of this method in the vision domain are well-studied, there is a lack of corresponding results, both qualitative and quantitative, for the text domain. We define and train language models on a set of formal grammars, and train SAEs on the latent representations of these models under a wide variety of hyperparameter settings. We identify several interpretable latents in the SAEs, and formulate a scaling law defining the relationship between the reconstruction loss of SAEs and their hidden size. We show empirically that the presence of latents correlating to certain features of the input does not imply a causal function in the computation and that the performance of SAEs is highly sensitive to inductive biases.
Large Language Models have been extensively studied for their vulnerabilities, particularly in the context of adversarial attacks. However, … (voir plus)the emergence of Vision Language Models introduces new modalities of risk that have not yet been thoroughly explored, especially when processing multiple images simultaneously. In this paper, we introduce two black-box jailbreak methods that leverage multi-image inputs to uncover vulnerabilities in these models. We present a new safety evaluation dataset for multimodal LLMs called MultiBench, which is composed of these jailbreak methods. These methods can easily be applied and evaluated using our toolkit. We test these methods against six safety aligned frontier models from Google, OpenAI, and Anthropic, revealing significant safety vulnerabilities. Our findings suggest that even the most powerful language models remain vulnerable against compositional adversarial attacks, specifically those composed of multiple images.
In-context learning (ICL) is the ability of a model to learn a new task by observing a few exemplars in its context. While prevalent in NLP,… (voir plus) this capability has recently also been observed in Reinforcement Learning (RL) settings. Prior in-context RL methods, however, require entire episodes in the agent's context. Given that complex environments typically lead to long episodes with sparse rewards, these methods are constrained to simple environments with short episodes. To address these challenges, we introduce Retrieval-Augmented Decision Transformer (RA-DT). RA-DT employs an external memory mechanism to store past experiences from which it retrieves only sub-trajectories relevant for the current situation. The retrieval component in RA-DT does not require training and can be entirely domain-agnostic. We evaluate the capabilities of RA-DT on grid-world environments, robotics simulations, and procedurally-generated video games. On grid-worlds, RA-DT outperforms baselines, while using only a fraction of their context length. Furthermore, we illuminate the limitations of current in-context RL methods on complex environments and discuss future directions. To facilitate future research, we release datasets for four of the considered environments.
Activation steering is a promising family of methods for controlling LLM outputs via targeted interventions on model activations. We introdu… (voir plus)ce a toy multi-label classification setup to systematically study activation steering methods, and experiment with several types of steering adapters — from steering vectors (adding a fixed vector to activations) to more expressive adapters involving projections. We evaluate the adapters across steering tasks of different complexities, for three notions of complexity: 1) how densely the features are packed in the representation space (roughly, number of features divided by the dimensionality of the activations), 2) number of attributes steered, and 3) number of values the steered attribute can take. We find that as task complexity is increased, steering vector methods perform worse, while the more expressive methods only take a performance hit when there is not enough data. On the other hand, steering vectors usually outperform more expressive methods in the low-data regime, regardless of task complexity. We conclude by discussing this work's limitations, which include our toy setup not modeling features represented in superposition or continuous features, and the lack of experiments with LLMs.
Representation engineering methods have recently shown promise for enabling efficient steering of model behavior. However, evaluation pipeli… (voir plus)nes for these methods have primarily relied on subjective demonstrations, instead of quantitative, objective metrics. We aim to take a step towards addressing this issue by advocating for four properties missing from current evaluations: (i) contexts sufficiently similar to downstream tasks should be used for assessing intervention quality; (ii) model likelihoods should be accounted for; (iii) evaluations should allow for standardized comparisons across different target behaviors; and (iv) baseline comparisons should be offered. We introduce an evaluation pipeline grounded in these criteria, offering both a quantitative and visual analysis of how effectively a given method works. We use this pipeline to evaluate two representation engineering methods on how effectively they can steer behaviors such as truthfulness and corrigibility, finding that some interventions are less effective than previously reported.
