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Hello, I am Ruyi Ji (吉如一). Welcome to my home page.

I'm now a fifth-year PhD student in the Programming Language Lab (PLL) at Peking University, advised by Prof. Zhenjiang Hu and Prof. Yingfei Xiong. I am interested in program synthesis and all related problems, like program optimization and verification. Click here for more about my research.

I completed my undergraduate at Peking University, where I worked with Prof. Yingfei Xiong on interactive program synthesis.

I used to be a contestant in competitive programming. I won the 3rd place, Gold medal in ACM/ICPC World Finals 2018. Now I'm still engaging in relevant activities. I'm the founder and the first president of PKU Student Algorithm Association. Click here for more about our activities.


  • April 1, 2024 Our paper Superfusion: Eliminating Intermediate Data Structures via Inductive Synthesis has been accepted at PLDI24. In this paper, we design an efficient inductive synthesizer for the fusion problem, the automatic elimination of intermediate data structures. Our approach not only significantly outperforms existing approaches on fusion, but also achieves comparable performance to AutoLifter, our previous approach specialized for synthesizing D&C-like algorithms. Try SuFu at our online demo.
  • January 1, 2024 Our paper Decomposition-Based Synthesis for Applying D&C-Like Algorithmic Paradigms has been accepted at TOPLAS. This is actually the first paper I worked on after I began my PhD, and it is finally accepted after three years of struggling. In this paper, we first propose a new type of synthesis tasks, namely lifting problems, to uniformly capture the application of a series of algorithmic paradigms (e.g., divide-and-conquer, incremental computation, and single-pass). Then, we propose an effective decomposition-based synthesizer for lifting problems. Our approach not only overcome the limitation of previous approaches to synthesize algorithms (that is, a strong requirement on the user-provided program) but also achieve a competitive (or even better) performance.
  • September 22, 2023 I will present my current research topic Scaling up Program Synthesis to Efficient Algorithms at SPLASH '23 Doctoral Symposium.
  • February 26, 2023 Our paper Improving Oracle-Guided Inductive Synthesis by Efficient Question Selection has been accepted at OOPSLA'23. In this paper, we design an efficient question selector that achieves general improvement for OGIS solvers. It reduces not only the number of OGIS iterations (valuable to interactive tasks) but also the time cost of solving non-interactive tasks. This paper is a follow-up to our PLDI'20 paper.
  • October 9, 2022 I am glad to receive Microsoft Research Asia Fellowship (i.e., Microsoft Research PhD Fellowship in the Asia-Pacific area)!