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Matei Zaharia

35 accepted papers

2026

Characterizing Agents in Production

ICML 2026oral

LLM-based agents already operate in production across many industries, yet we lack a clear understanding of which technical methods make these deployments successful. We present the first systematic study of Characterizing Agents in Production (CAP) using first-hand data from agent developers. We co…

Cited by 0SourceScholar
2026

DS SERVE: A Framework for Efficient and Scalable Neural Retrieval

AAAI 2026technical

We present DS SERVE, a framework that transforms large-scale text datasets—comprising half a trillion tokens—into a high-performance neural retrieval system. DS SERVE offers both a web interface and API endpoints, achieving low latency with modest memory overhead on a single node. The framework also

Cited by 0SourcePDFScholar
2026

EXP-Bench: Can AI Conduct AI Research Experiments?

ICLR 2026poster

Automating AI research holds immense potential for accelerating scientific progress, yet current AI agents struggle with the complexities of rigorous, end-to-end experimentation. We introduce EXP-Bench, a novel benchmark designed to systematically evaluate AI agents on complete research experiments…

Cited by 0SourcecodeScholar
2026

GEPA: Reflective Prompt Evolution Can Outperform Reinforcement Learning

ICLR 2026oral

Large language models (LLMs) are increasingly adapted to downstream tasks via reinforcement learning (RL) methods like Group Relative Policy Optimization (GRPO), which often require thousands of rollouts to learn new tasks. We argue that the interpretable nature of language often provides a much ric…

Cited by 0SourcecodeScholar
2026

How to Train Your Advisor: Steering Black-Box LLMs with Advisor Models

ICML 2026poster

Frontier language models are deployed as black-box services, where model weights cannot be modified and customization is limited to prompting. We introduce Advisor Models, a method to train small open-weight models to generate dynamic, per-instance natural language advice that improves the capabilit…

Cited by 0SourceScholar
2026

Reliable Fine-Grained Evaluation of Natural Language Math Proofs

ICLR 2026poster

Recent advances in large language models (LLMs) for mathematical reasoning have largely focused on tasks with easily verifiable final answers while generating and verifying natural language math proofs remains an open challenge. We identify the absence of a reliable, fine-grained evaluator for LLM-g…

Cited by 0SourcecodeScholar
2026

vAttention: Verified Sparse Attention via Sampling

ICLR 2026poster

State-of-the-art sparse attention methods for reducing decoding latency fall into two main categories: approximate top-$k$ (and its extension, top-$p$) and recently introduced sampling-based estimation. However, these approaches are fundamentally limited in their ability to approximate full attentio…

Cited by 0SourcecodeScholar
2026

vCache: Verified Semantic Prompt Caching

ICLR 2026poster

Semantic caches return cached responses for semantically similar prompts to reduce LLM inference latency and cost. They embed cached prompts and store them alongside their response in a vector database. Embedding similarity metrics assign a numerical score to quantify the similarity between a reques…

Cited by 0SourcecodeScholar
2025

ElasticTok: Adaptive Tokenization for Image and Video

ICLR 2025poster

Efficient video tokenization remains a key bottleneck in learning general purpose vision models that are capable of processing long video sequences. Prevailing approaches are restricted to encoding videos to a fixed number of tokens, where too few tokens will result in overly lossy encodings, and to…

2025

Establishing Best Practices in Building Rigorous Agentic Benchmarks

NeurIPS 2025poster

Benchmarks are essential for quantitatively tracking progress in AI. As AI agents become increasingly capable, researchers and practitioners have introduced agentic benchmarks to evaluate agents on complex, real-world tasks. These benchmarks typically measure agent capabilities by evaluating task ou…

Cited by 0SourceScholar
2025

HashAttention: Semantic Sparsity for Faster Inference

ICML 2025poster

Leveraging long contexts is crucial for advanced AI systems, but attention computation poses a scalability challenge. While scaled dot-product attention (SDPA) exhibits token sparsity, i.e. only a few pivotal tokens significantly contribute to output, exploiting this sparsity remains challenging. Ex…

Cited by 3SourcePDFScholar
2025

LangProBe: a Language Program Benchmark

EMNLP 2025

Composing language models (LMs) into multi-step language programs and automatically optimizing their modular prompts is now a mainstream paradigm for building AI systems, but the tradeoffs in this space have only scarcely been studied before. We introduce LangProBe, the first large-scale benchmark f

Cited by 0SourcePDFScholar
2025

Language Models Can Easily Learn to Reason from Demonstrations

EMNLP 2025

Large reasoning models (LRMs) tackle complex problems by following long chain-of-thoughts (Long CoT) that incorporate reflection, backtracking, and self-validation. However, the training techniques and data requirements to elicit Long CoT remain poorly understood. In this work, we find that language

Cited by 0SourcePDFScholar
2025

Why Do Multi-Agent LLM Systems Fail?

NeurIPS 2025spotlight

Despite enthusiasm for Multi-Agent LLM Systems (MAS), their performance gains on popular benchmarks are often minimal. This gap highlights a critical need for a principled understanding of why MAS fail. Addressing this question requires systematic identification and analysis of failure patterns. We…

Cited by 0SourcecodeScholar
2025

World Model on Million-Length Video And Language With Blockwise RingAttention

ICLR 2025poster

Enabling long-context understanding remains a key challenge in scaling existing sequence models -- a crucial component in developing generally intelligent models that can process and operate over long temporal horizons that potentially consist of millions of tokens. In this paper, we aim to address…

2024

ARES: An Automated Evaluation Framework for Retrieval-Augmented Generation Systems

NAACL 2024long

Evaluating retrieval-augmented generation (RAG) systems traditionally relies on hand annotations for input queries, passages to retrieve, and responses to generate. We introduce ARES, an Automated RAG Evaluation System, for evaluating RAG systems along the dimensions of context relevance, answer fai…

2024

Are More LLM Calls All You Need? Towards the Scaling Properties of Compound AI Systems

NeurIPS 2024poster

Many recent state-of-the-art results in language tasks were achieved using compound systems that perform multiple Language Model (LM) calls and aggregate their responses. However, there is little understanding of how the number of LM calls -- e.g., when asking the LM to answer each question multiple…

Cited by 13SourcePDFScholar
2024

DSPy: Compiling Declarative Language Model Calls into State-of-the-Art Pipelines

ICLR 2024spotlight

The ML community is rapidly exploring techniques for prompting language models (LMs) and for stacking them into pipelines that solve complex tasks. Unfortunately, existing LM pipelines are typically implemented using hard-coded “prompt templates”, i.e. lengthy strings discovered via trial and error.…

2024

Optimizing Instructions and Demonstrations for Multi-Stage Language Model Programs

EMNLP 2024main

Language Model Programs, i.e. sophisticated pipelines of modular language model (LM) calls, are increasingly advancing NLP tasks, but they require crafting prompts that are jointly effective for all modules. We study prompt optimization for LM programs, i.e. how to update these prompts to maximize a…

2024

RingAttention with Blockwise Transformers for Near-Infinite Context

ICLR 2024poster

Transformers have emerged as the architecture of choice for many state-of-the-art AI models, showcasing exceptional performance across a wide range of AI applications. However, the memory demands imposed by Transformers limit their ability to handle long sequences, thereby posing challenges in utili…

2023

HAPI Explorer: Comprehension, Discovery, and Explanation on History of ML APIs

AAAI 2023technical

Machine learning prediction APIs offered by Google, Microsoft, Amazon, and many other providers have been continuously adopted in a plethora of applications, such as visual object detection, natural language comprehension, and speech recognition. Despite the importance of a systematic study and comp…

Cited by 1SourcePDFScholar
2023

Moving Beyond Downstream Task Accuracy for Information Retrieval Benchmarking

ACL 2023findings

Neural information retrieval (IR) systems have progressed rapidly in recent years, in large part due to the release of publicly available benchmarking tasks. Unfortunately, some dimensions of this progress are illusory: the majority of the popular IR benchmarks today focus exclusively on downstream…

2022

ColBERTv2: Effective and Efficient Retrieval via Lightweight Late Interaction

NAACL 2022long

Neural information retrieval (IR) has greatly advanced search and other knowledge-intensive language tasks. While many neural IR methods encode queries and documents into single-vector representations, late interaction models produce multi-vector representations at the granularity of each token and…

2022

Efficient Online ML API Selection for Multi-Label Classification Tasks

ICML 2022spotlight

Multi-label classification tasks such as OCR and multi-object recognition are a major focus of the growing machine learning as a service industry. While many multi-label APIs are available, it is challenging for users to decide which API to use for their own data and budget, due to the heterogeneity…

2022

Estimating and Explaining Model Performance When Both Covariates and Labels Shift

NeurIPS 2022accept

Deployed machine learning (ML) models often encounter new user data that differs from their training data. Therefore, estimating how well a given model might perform on the new data is an important step toward reliable ML applications. This is very challenging, however, as the data distribution can…

Cited by 24SourcePDFScholar
2022

HAPI: A Large-scale Longitudinal Dataset of Commercial ML API Predictions

NeurIPS 2022accept

Commercial ML APIs offered by providers such as Google, Amazon and Microsoft have dramatically simplified ML adoptions in many applications. Numerous companies and academics pay to use ML APIs for tasks such as object detection, OCR and sentiment analysis. Different ML APIs tackling the same task ca…

2022

Hindsight: Posterior-guided training of retrievers for improved open-ended generation

ICLR 2022poster

Many text generation systems benefit from retrieving passages from a textual knowledge corpus (e.g., Wikipedia) and using them to generate the output. For open-ended generation tasks, like generating informative utterances in conversations, many varied passages $z$ are relevant to the context $x$ bu…

Cited by 49SourcePDFScholar
2022

How Did the Model Change? Efficiently Assessing Machine Learning API Shifts

ICLR 2022poster

ML prediction APIs from providers like Amazon and Google have made it simple to use ML in applications. A challenge for users is that such APIs continuously change over time as the providers update models, and changes can happen silently without users knowing. It is thus important to monitor when an…

Cited by 19SourcePDFScholar
2022

Similarity Search for Efficient Active Learning and Search of Rare Concepts

AAAI 2022technical

Many active learning and search approaches are intractable for large-scale industrial settings with billions of unlabeled examples. Existing approaches search globally for the optimal examples to label, scaling linearly or even quadratically with the unlabeled data. In this paper, we improve the com…

Cited by 41SourcePDFScholar
2021

Baleen: Robust Multi-Hop Reasoning at Scale via Condensed Retrieval

NeurIPS 2021spotlight

Multi-hop reasoning (i.e., reasoning across two or more documents) is a key ingredient for NLP models that leverage large corpora to exhibit broad knowledge. To retrieve evidence passages, multi-hop models must contend with a fast-growing search space across the hops, represent complex queries that…

Cited by 65SourcePDFScholar
2021

Memory-Efficient Pipeline-Parallel DNN Training

ICML 2021spotlight

Many state-of-the-art ML results have been obtained by scaling up the number of parameters in existing models. However, parameters and activations for such large models often do not fit in the memory of a single accelerator device; this means that it is necessary to distribute training of large mode…

Cited by 274SourcePDFScholar
2020

FrugalML: How to use ML Prediction APIs more accurately and cheaply

NeurIPS 2020oral

Offering prediction APIs for fee is a fast growing industry and is an important aspect of machine learning as a service. While many such services are available, the heterogeneity in their price and performance makes it challenging for users to decide which API or combination of APIs to use for their…

2020

Selection via Proxy: Efficient Data Selection for Deep Learning

ICLR 2020poster

Data selection methods, such as active learning and core-set selection, are useful tools for machine learning on large datasets. However, they can be prohibitively expensive to apply in deep learning because they depend on feature representations that need to be learned. In this work, we show that w…

Cited by 391SourcecodeScholar
2019

LIT: Learned Intermediate Representation Training for Model Compression

ICML 2019oral

Researchers have proposed a range of model compression techniques to reduce the computational and memory footprint of deep neural networks (DNNs). In this work, we introduce Learned Intermediate representation Training (LIT), a novel model compression technique that outperforms a range of recent mod…

Cited by 80SourcePDFScholar
2016

Yggdrasil: An Optimized System for Training Deep Decision Trees at Scale

NeurIPS 2016poster

Deep distributed decision trees and tree ensembles have grown in importance due to the need to model increasingly large datasets. However, PLANET, the standard distributed tree learning algorithm implemented in systems such as \xgboost and Spark MLlib, scales poorly as data dimensionality and tree…

Cited by 31SourcePDFScholar