CV

Curriculum vitae.

Contact Information

Name Zaiyi Zheng
Professional Title Ph.D. Student
Email sjc4fq@virginia.edu
Website https://zhengzaiyi.github.io

Summary

Ph.D. student in Computer Engineering at the University of Virginia, advised by Professor Jundong Li. My research interests lie in recommendation systems, retrieval-augmented generation, and large language models.

Education

  • 2023 - present

    Charlottesville, VA, United States

    Ph.D.
    University of Virginia
    Computer Engineering
  • 2018 - 2022

    Hefei, Anhui, China

    B.E.
    University of Science and Technology of China
    Computer Science

Industry Experience

  • 2026 - 2027

    Bellevue, WA, United States

    Research Advisor II
    Meta
    Topic: LLM for Recommendation. Adviser: Dr. Cassie Dong.
    • Built a large-scale transformer-based model for effective and efficient ads ranking.
  • 2026 - 2026

    Sunnyvale, CA, United States

    Machine Learning Research Intern
    Nokia America
    Topic: Generative Recommendation. Adviser: Dr. Liang Wu.
    • Studied semantic ID (SID) based generative recommendation with large language models, focusing on reasoning-aware generation and efficient inference.
    • Constructed explicit Chain-of-Thought (CoT) reasoning traces for each meta token in SID generation and trained a teacher model with a two-stage SFT-then-RL pipeline.
    • Introduced auxiliary soft-thinking tokens for approximately 1B-parameter student models and distilled the teacher’s CoT into continuous latent embeddings.
    • Deployed only the student model at inference time, achieving comparable ranking quality to explicit CoT-based generation with reduced latency and generation cost.
  • 2025 - 2025

    Bellevue, WA, United States

    Machine Learning Research Intern
    Snap Inc.
    Topic: Agentic Recommendation Systems. Adviser: Dr. Clark Ju.
    • Developed a personalized LLM-based agent for multi-channel item recall by extending Hugging Face’s TRL framework.
    • Designed and implemented a soft-token mechanism to structurally generate routing weights over recall channels.
    • Modified the vLLM inference engine to support high-throughput soft-token decoding and agent-style online interaction.
    • Adapted Group Relative Policy Optimization (GRPO) to optimize adaptive routing over multiple recall models.
  • 2024 - 2025

    Bellevue, WA, United States

    Research Assistant
    Snap Inc.
    Topic: Cold-Start Item Recommendation. Adviser: Dr. Neil Shah.
    • Developed an adaptive cold-start item recommendation system for rapidly emerging items with sparse or zero interaction histories.
    • Proposed MI4Rec, a PLM-based cold-start recommender that infers item representations via meta-item embedding composition.
    • Evaluated on Amazon-Beauty, Toys, Sports, and Yelp under cold-start, warm-start, and general settings, achieving up to 15.71% relative improvement in Recall.
  • 2022 - 2022

    Hangzhou, Zhejiang, China

    Machine Learning Engineer Intern
    Zerozero Robotics
    Topic: Trajectory Planning. Adviser: Hao Zhang.
    • Built an outdoor trajectory planning system for physical quadrotors and constructed realistic evaluation environments in Unity.
    • Reproduced an imitation learning framework and incorporated data aggregation to improve obstacle avoidance.
    • Achieved an 18.2% relative reduction in navigation failure rate in outdoor environments.

Academic Experience

  • 2023 - present

    Charlottesville, VA, United States

    Research Assistant
    University of Virginia
    Topic: Retrieval-Augmented Generation (RAG). Adviser: Prof. Jundong Li.
    • Proposed CoRAG, a hybrid RAG framework that dynamically selects between global textual retrieval and graph-based relational retrieval.
    • Designed a Cooperative-Retrievers (CoR) mixture-of-retrievers module with hierarchical gating to adaptively fuse heterogeneous retrieval signals.
    • Demonstrated strong performance on STaRK semi-structured KGQA benchmarks, achieving up to 11.4% relative Hit@1 improvement over prior RAG baselines.
  • 2021 - 2021

    Austin, TX, United States

    Research Assistant
    University of Texas at Austin
    Topic: Indoor Navigation. Adviser: Dr. Wuyang Chen.
    • Developed an efficient and transferable robot navigation method for sim-to-real deployment.
    • Implemented a PPO-based navigation pipeline on Meta’s Habitat platform.
    • Proposed a contrastive learning component for visual representation learning with positive and negative sampling.

Interests

Research Areas: recommendation systems, retrieval-augmented generation, large language models, graph learning

Skills

Field of Study: Recommendation System, Retrieval Augmented Generation
Programming and Tools: Python, PyTorch, Pandas, C++, Unity, LaTeX, Git, Linux

Awards

  • 2025
    Student Travel Award

    CIKM 2025 and BigData 2024.

  • 2019
    Silver Scholarship for Outstanding Students

    University of Science and Technology of China, 2019 - 2022.

  • 2019
    Talents Class Scholarship

    University of Science and Technology of China.