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Aaron Feng

$whoami

Aaron Feng

MS CS, UT Austin BS, UC San Diego

About//about

I’m a first-year Computer Science master’s student at UT Austin. I did my BS in Data Science and Probability & Statistics at UC San Diego.

Two things I work on:

  • Memory for LLM agents: giving an agent a way to keep what it worked out on one problem and put it to use on the next.
  • Efficient inference: mostly speculative decoding, getting a cheap draft model to propose tokens the real model will actually accept.

Selected Publications//selected_publications

Under review — NeurIPS 2026

JetSpec: Breaking the Scaling Ceiling of Speculative Decoding with Parallel Tree Drafting

JetSpec's method figure: fused target-model features feed a causal-parallel draft head that drafts a candidate tree in one forward pass, then the frozen target model verifies it.

Lanxiang Hu, Zhaoxiang Feng, Yulun Wu, Haoran Yuan, Yujie Zhao, Yu‑Yang Qian, Bojun Wang, Peng Zhao, Daxin Jiang, Yibo Zhu, Tajana Rosing, Hao Zhang

A causal parallel draft head over fused hidden states, combining one-forward drafting with branch-wise causal conditioning — up to 9.64× speedup on math and 4.58× on chat with Qwen3.

Runner‑up — ARC Prize 2025 Paper Awards

ArcMemo: Abstract Reasoning Composition with Lifelong LLM Memory

ArcMemo's method diagram: how memory is formatted, written from a solved puzzle's trace, and read back for a new problem, in both the open-ended and program-synthesis formats.

Matthew Ho, Chen Si, Zhaoxiang Feng, Fangxu Yu, Yichi Yang, Zhijian Liu, Zhiting Hu, Lianhui Qin

A concept-level memory that lets an LLM agent distill reasoning traces into reusable abstractions and keep learning at test time without weight updates.

Research Experience//research_experience

Hao AI Lab, UC San Diego Advised by Hao Zhang and Lanxiang Hu · Sep 2025–Present

  • Led JetSpec++, a causal correction for parallel drafting that conditions each drafted token on its full branch history rather than on the preceding token alone. At matched parameter count it outperformed DeepSeek’s DSpark, with the margin widening at draft depths beyond those used in training.
  • Contributed to JetSpec, a draft head that generates a complete speculative tree in one forward pass while preserving the target model’s autoregressive factorization along every branch; built its standalone inference engine (paged KV cache, Triton tree‑attention kernel, CUDA‑graph verification) and its evaluation suite. Reaches up to 9.64× end‑to‑end speedup over autoregressive decoding on Qwen3‑8B (MATH‑500).
  • Ported DFlash speculative decoding to TPU in JAX as the primary contributor, showing that verification cost stays flat in draft block size through K=1024. Averaged 3.13× speedup on TPU v5p; the draft model and proposer are merged into vLLM’s TPU backend, with pipeline integration in review, and the work is featured on the Google Developers Blog.
  • Built the training stack for a 1.8B‑parameter language model on eight NVIDIA B200 GPUs, implementing the full pre‑training and SFT and DPO post‑training system with DDP and ZeRO‑1.

Q‑Lab, UC San Diego Advised by Lianhui Qin and Matthew Ho · Jan 2025–Jun 2026

  • Contributed to the design of ArcMemo’s program‑synthesis memory ontology, a typed, parameterized representation in which reusable reasoning concepts are stored and composed.
  • Worked on the reasoning‑guided concept selection that replaced embedding‑based retrieval, after embedding search proved ineffective on the ARC‑AGI‑1 abstract‑reasoning benchmark.
  • Built the pipeline that produces concept‑labeled helper puzzles: each hand‑written concept is expanded by an LLM into puzzle‑generating code, which is executed and tested so that every generated puzzle is verified to exercise its concept.
  • Designed the framework’s adaptation to AIME competition mathematics and ran the generalization experiments and memory‑format comparisons that informed the final design.