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Hamed's Webpage

Machine Learning and AI

Hamed Firooz

I have over 15+ years of experience delivering large-scale AI solutions and leading multi-year technology strategies. I’ve spent more than seven years managing research and engineering teams across multiple sites, driving innovation and impact in AI.

  • Current position: Principal (Director) AI Scientist at Meta AI
  • Education: PhD from University of Washington (UW)

Experience

  • 2025 - Current
    Principal Staff (Director) AI Scientist
    Meta AI

    WIP

  • 2023 - 2025
    Principal Staff AI Scientist
    LinkedIn Core AI

    I have formed and currently lead a team of over 50 AI scientists and engineers to pre-train, post-train, and deploy a 150B+ parameter foundational model for LinkedIn’s personalization tasks at scale.

  • 2018 - 2023
    Sr. Staff AI Tech Lead Manager
    Meta AI

    Led a medium-sized team with diverse profiles, research scientists and software engineers. Our mission was to advance AI technologies to keep users safe online. My team built multimodal content understanding services used across many Meta integrity products.

  • 2012 - 2018
    AI/ML Engineer & Tech Lead Manager
    Multiple High-Growth Technology Companies

    Built and scaled AI/ML-driven products and engineering teams at venture-backed and public technology companies, contributing to successful acquisitions.

    Worked across product development, applied machine learning, and technical leadership in environments that scaled from early stage to acquisition.

    Select outcomes: Base CRM (acquired by Zendesk), Falkonry (acquired by IFS), LinkedIn (acquired by Microsoft).

  • 2011 - 2012
    Adjunct Lecture - CS/EE department
    Univerity of Washington, Seattle

    Designed and taught advanced undergraduate and graduate 4-credit courses in probability theory, random variables, stochastic processes, and random signals, integrating theoretical rigor with statistical machine learning and its applications.

Education

  • 2012
    PhD (Electrical Engineering)
    University of Washington

    Compressed Sensing and Network Coding

  • 2008
    MSc
    University of Tehran

    Peer-to-peer networks

Featured Projects
Highlights & News
  • 2026
  • [Jan 2026] Our second recipe for scaling Reinforcement Learning focuses on a high-impact setting: ranking and re-ranking models.

    GR2 (Generative Reasoning Re-ranker) demonstrates strong gains for LLM-based re-ranking, outperforming recent work such as Google DeepMind’s PLUM and Kuaishou’s OneRec-Think. GR2 extends reasoning traces by enabling the LLM to invoke an optimized tool that loads item features associated with a Semantic ID directly into its context. These reasoning traces are a key lever for performance improvements and are optimized using Reinforcement Learning with verifiable rewards. We also present a practical recipe to prevent reward hacking.

  • 2025
  • [Dec 2025] Publishing our work on Scaling Reinforcement Learning for Content Moderation with LLMs

    RL post-training as a practical lever for turning general-purpose LLMs into specialized, policy-aligned classifiers. We demonstrate that RL 1. follows Sigmoid-like scaling behavior, 2. provides Strong label efficiency compared to SFT 3. need careful recipe for reward shaping and Monte-Carlo score aggregation to stabilize training and improve reliability.

  • [Oct 2025] Our second paper in a series on understanding how LLM Chain-of-Thought works—this time focusing on how and when LLMs benefit from reasoning.

    As the second paper in a series on understanding chain-of-thought and in-context learning, this work investigates the role of CoT meta-training in shaping reasoning behavior in LLMs. We show that while CoT can accelerate learning, excessive reliance on explicit reasoning traces can harm generalization, and we outline principled strategies for effective CoT usage.

  • [Aug 2025] Back to Meta AI and teaching machines to be intelligent

    Move fast and live in future

  • [June 2025] Gave a talk about 360Brew and its productionization at AI Engineer World's Fair.

    The video of the talk is available on Youtube and the slides can be access on here

  • [April 2025] Gave a talk on 360Brew at the LinkedIn AI & Data Community event.

    I explained how 360Brew unifies core AI components into a single layer, streamlining ranking and recommendation workflows, eliminating technical debt, and accelerating developer productivity.

  • [Feb 2025] To get insight into In-Context Learning and Chain-of-Thought reasoning we published CoT-ICL Lab

    CoT-ICL Lab is a framework to study chain-of-thought (CoT) and in-context learning (ICL) by decoupling causal structure from token processing functions. Experiments show that 1) CoT accelerates the accuracy transition to higher values across model sizes 2) deeper models require fewer in-context examples to leverage CoT effectively while more examples help shallow models match deeper model performance. Along with detailed analyses we provide theoretical insights. The code is available here.

  • [Feb 2025] We released our technical report about how to productionize 360Brew, our LLM-based foundation model for LinkedIn personalization products

    In this work we show how to leverage On-Policy forward Knowledge Distillation, Model Compression (Pruning and Quantization), and Serving Optimizations (detailed on RadixAttention, FlashInfer, and tensor parallelism) to deliver a 20x reduction in both cost and latency while maintaining the quality of our 360Brew XL model.

  • 2024
  • [Dec 2024] We released our technical report on LLM-based foundation model for personalized predictions.

    In this report, we demonstrate that 360Brew model, a 150B parameter foundation model trained on 1T tokens can solve over 30 personalization tasks on LinkedIn platform without task-specific fine-tuning and no complex feature engineering. It can generalize to out-of-domain tasks and surfaces, and achieves performance similar to or better than the production model.

  • [Oct 2024] We published our findings, about LLM Lost-in-Distance phenomena.

    In this work we demonstrate that LLM's performance is affected by the relative distance between pieces of information in the context. The further apart the information is within long context, the more the model’s performance deteriorates.

  • [Aug 2024] My team open-sourced Liger Kernel for memory efficient and fast LLM training.

    Liger Kernel is a collection of Triton kernels designed specifically for LLM training. It can effectively increase multi-GPU training throughput by 20% and reduces memory usage by 60%.

  • [May 2024] Enhancing Stability for Large Language Models Training in Constrained Bandwidth Networks is accepted to ICML'24 FoMo-ES workshop.

    This system-model co-design work focuses on leveraging synchronization in data parallelism hierarchical partitioning to avoid race condition in gradient updates for LLM training.

  • [Mar 2024] RESPROMPT: Residual Connection Prompting Advances Multi-Step Reasoning in Large Language Models is accepted to NACCL'24.

    We formulate CoT as a reasoning graph and propose a prompt strategy for multi-step reasoning that can capture complex processes in tasks such as mathematics and commonsense reasoning.

  • [Feb 2024] My team contributed to Open Source DeepSpeed implementation of ZeRO++ hierarchical partitioning.

    The race condition between AllGather and device-to-device copy for the 2nd partition causes instability in training large models such as Llama-7B and Falcon-40B on a moderately large number of GPUs. After discovering the algorithmic issue, we landed the fix in the DeepSpeed repository.

  • 2023
  • [Sep 2023] Our paper on Understanding the detrimental class-level effects of data augmentation is accepted to Neurips 2023.

    We propose a framework for understanding how Data Augmentation interacts with class-level learning dynamics. We show that simple class-conditional augmentation strategies informed by our framework improve performance on the negatively affected classes.

    [Jun 2023] My team’s content- and preference-understanding AI foundation models lifted Reels watch-time by 15 percent.

    Leveraging multimodal foundation models — XLM-R for language and FLAVA (plus MViT) for vision/video — to parse semantics across text, images and clips, we pair a hierarchical retrieval-and-ranking stack that distills billions of posts into the few hundred most relevant to each person in milliseconds, fueling unconnected-content discovery across Feed, Explore and Reels.

  • 2022
  • [Oct 2022] My team launched one-tap “Show More / Show Less” controls that let people directly steer their recommendations.

    We trained a deep learning model on millions of explicit SMSL feedback, fusing them with existing engagement features to predict how users preference on new content—and then blend that preference score into real-time ranking. The result: giving everyone finer-grained, self-tuning personalization.

  • 2021
  • [2021] Launched FAIM (Facebook AI Multimodal), a comprehensive framework for multimodal content integrity.

    FAIM consolidated dozens of individual models into a unified PyTorch-based framework that processes text, images, and video simultaneously. This shift to generalized AI improved detection of hate speech, bullying, harassment, and violence while reducing computational overhead. The framework now powers over 85% of Facebook's multimodal integrity models and includes advanced features like Whole Post Integrity Embeddings (WPIE) for contextual understanding across content types.

  • WIP
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