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Yifeng He
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About Me

Hey there! I’m 贺一峰 (He, Yifeng), a second-year Ph.D. student at UC Davis. My advisor is Professor Hao Chen. I got my B.S. (with Honors) from UC Davis too, double majoring in Applied Math and Computer Science. During undergrad, I also served as president of HackerHub, a student-run tech club on campus.

These days, I spend most of my time thinking about how AI and software engineering can help each other out. More specifically, my research interests are:

  • using AI to improve software engineering, with focus on testing and security,
  • making AI itself more secure — both foundation models and agents,
  • building better AI models for software engineering,
  • safe and secure programming languages (bonus points if they’re functional and useful for AI).

I’m also into video games. Some of my all-time favorites include Pokémon (recently played Sword 🙃, Violet, and Arceus 😊), The Witcher 3, Clash of Clans (hit world rank #169 back in April 2018!), and Genshin Impact (though I haven’t touched it since 4.4, thanks miHoYo 😅). Other games I’ve enjoyed or recommend: The Legend of Zelda series, Palworld (was obsessed for a while… then drifted back to egg hatching in Pokémon), and Whimel Academy.

I also enjoy powerlifting. I have trained for a little over two years. My (training) personal records are Squat 405lb (184kg), Bench Press 245lb (111kg), Deadlift 455lb (206kg) summing up to 1105lb (501kg) @ 85kg body weight. I also dabble in photography. If you’re curious, feel free to check out some of my shots on Instagram.

Curriculum vitae pdf

Education

Ph.D. in Computer Science

University of California, Davis (2023 – present)

B.S. in Computer Science and Applied Mathematics

University of California, Davis (2019 – 2023)

Publications

Peer-reviewed Papers

Yifeng He, Ethan Wang, Yuyang Rong, Zifei Cheng, Hao Chen. Security of AI Agents, International Workshop on Responsible AI Engineering (ICSE-RAIE), 2025. doi, pdf, code, slides, arXiv (with more figures!).

Yifeng He, Jiabo Huang, Yuyang Rong, Yiwen Guo, Ethan Wang, Hao Chen. UniTSyn: A Large-Scale Dataset Capable of Enhancing the Prowess of Large Language Models for Program Testing, International Symposium on Software Testing and Analysis (ISSTA), 2024. doi, pdf, code, slides, poster.

Jiabo Huang, Jianyu Zhao, Yuyang Rong, Yiwen Guo, Yifeng He, Hao Chen. Code Representation Pre-training with Complements from Program Executions. Empirical Methods in Natural Language Processing: Industry Track (EMNLP), 2024. doi, pdf, poster.

Jianyu Zhao, Yuyang Rong, Yiwen Guo, Yifeng He, Hao Chen. Understanding Programs by Exploiting (Fuzzing) Test Cases, Findings of Association for Computational Linguistics (ACL), 2023. doi, pdf, code.

Yifeng He, Big Data and Deep Learning Techniques Applied in Intelligent Recommender Systems, International Conference on Civil Aviation Safety and Information Technology (ICCASIT), 2022. doi.

Preprints

Hongxiang Zhang, Yifeng He, Hao Chen. SteerDiff: Steering towards Safe Text-to-Image Diffusion Models. https://arxiv.org/abs/2410.02710

Jicheng Wang, Yifeng He, Hao Chen. RepoGenReflex: Enhancing Repository-Level Code Completion with Verbal Reinforcement and Retrieval-Augmented Generation. https://arxiv.org/abs/2409.13122

Yifeng He, Jicheng Wang, Yuyang Rong, Hao Chen. FuzzAug: Data Augmentation by Fuzzing for Neural Test Generation. https://arxiv.org/abs/2406.08665

Hongxiang Zhang, Yuyang Rong, Yifeng He, Hao Chen. LLAMAFUZZ: Large Language Model Enhanced Greybox Fuzzing. https://arxiv.org/abs/2406.07714

Honors and Awards

Citation For Outstanding Performance, Dept. Mathematics, UC Davis

Dean’s Honor List, Fall 2019, Spring 2020, Spring 2021, Spring 2022, College of L&S, UC Davis

Teaching

  • ECS 36C Data Structure
    • TA, Spring 2023
    • TA, Fall 2023

Internship

ByteDance, Beijing, China 04/2021 - 08/2021

Software Engineering Intern in Income Platform Team

  • Used microservice tech to connect parts of the author income settlement bushiness
  • Transformed author-relation data architecture design from relational database (SQL) to graph database (Gremlin) to allow better efficiency for the business model
  • Refactored the income calculation control process with visitor design pattern using Python 3
  • Created a data cleaner script with ORM to maintain the size and readability of online data settlement table
  • Created the offline flow of Medium Video Encouragement Project for weekly data calculation
  • Built the interface for frontend of web and mobile app to display the data visualization

Projects

CourseReco 06/2022 - 09/2022

  • Designed the overall system architecture
  • Led the programming for API server and recommender engine
  • Negotiated with the third-party provider, SchedGo, for data service
  • Provided technical leadership to teammates

Music Genre Classifier 05/2022 - 06/2022

  • Processed music samples into spectrogram by Short-time Fourier transform
  • Designed the appropriate model (CNN) to classify spectrograms into category
  • Analyzed the resulting model and test outputs with saliency maps

ImageOrientation 03/2022 - 04/2022

  • Pre-processed image data by rotating them with random generated angles, and assigned these angles as label
  • Designed the appropriate CNN for regression task, tested and improved the model
  • Applied Hyper-parameter tuning based on train, validation, and tested results

Dcash-server 05/2021 - 07/2021

  • Created a multi-threaded API server using C++ to allow users to create accounts to make deposit and transfer
  • Used MySQL to store and maintain user data
  • Made API calls to the Stripe API server to handle credit card information

Genshine Impact Gacha Analyzer 08/2021 - 09/2021

  • Designed fetching process of gacha data from MiHoYo and categorized the process
  • Stored data into local database automatically, wrote into excel for data analysis by option
  • Generated text or graph visualization report from data analyze results

Activities

HackerHub Club, UC Davis 07/2020 - 06/2023

Co-founder, President, Technical Officer

  • Design and maintain a course recommendation system, CourseReco, for UC Davis students
  • Organize and lead the Code Jam Competition on data visualization, AI, augmented reality and virtual reality, and machine learning
  • Coach in introductory programming workshops, including Assembly, functional programming, recommender system, generative adversarial network, etc.