PhD at Tsinghua University. Working on #ML & #NLProc

Beijing, China
Joined September 2014
Yingfa Chen retweeted
a life update: i started a new company called Pragmatik (p7k) Labs (语用科技) in shanghai, focusing on the research of next-generation agents across digital and physical worlds. thanks to Gaorong Ventures and HSG (红杉中国 & 高榕创投) for co-leading this round, and to Tencent (腾讯) and Shanghai Engine Fund (上海未来产业基金) for the support. @pragmatik_labs · pragmatik.com
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Yingfa Chen retweeted
(1/n)If you paste your data into an LLM and ask it to plot it in Python, it first has to copy every number into the code — so can you trust the result, or might it quietly miscopy a few? Our new paper finds frontier LMs sometimes do get this wrong! Models that can solve hard reasoning problems still fail at a much simpler task: copying an input exactly, token by token. Why? RoPE has an inductive bias that works against exact copying. Better option? we propose 2D-RoPE, which views text as 2D instead of 1D.
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Yingfa Chen retweeted
I found out the other day that any compression tool can be contorted to do language modeling. Turns out gzip can generate text that somewhat *resembles* Shakespeare. Short write up linked below
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Yingfa Chen retweeted
The TurboQuant paper (ICLR 2026) contains serious issues in how it describes RaBitQ, including incorrect technical claims and misleading theory/experiment comparisons. We flagged these issues to the authors before submission. They acknowledged them, but chose not to fix them. The paper was later accepted and widely promoted by Google, reaching tens of millions of views. We’re speaking up now because once a misleading narrative spreads, it becomes much harder to correct. We’ve written a public comment on openreview (openreview.net/forum?id=tO3A…). We would greatly appreciate your attention and help in sharing it.
Introducing TurboQuant: Our new compression algorithm that reduces LLM key-value cache memory by at least 6x and delivers up to 8x speedup, all with zero accuracy loss, redefining AI efficiency. Read the blog to learn how it achieves these results: goo.gle/4bsq2qI
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Yingfa Chen retweeted
We are disappointed to see that the TurboQuant team has not directly responded to our concerns majorly on Openreview. Their reply even suggests that we had not raised these technical points to them through academic channels over the past year, which is factually incorrect. We have submitted our email records with the TurboQuant team to ICLR Chairs. According to ICLR Code of Ethics “Researchers must not deliberately make false or misleading claims, fabricate or falsify data, or misrepresent results. Methods and results should be presented in a way that is transparent and reproducible. ”, we respectfully request that ICLR initiates a formal research-integrity review of this paper.
The TurboQuant paper (ICLR 2026) contains serious issues in how it describes RaBitQ, including incorrect technical claims and misleading theory/experiment comparisons. We flagged these issues to the authors before submission. They acknowledged them, but chose not to fix them. The paper was later accepted and widely promoted by Google, reaching tens of millions of views. We’re speaking up now because once a misleading narrative spreads, it becomes much harder to correct. We’ve written a public comment on openreview (openreview.net/forum?id=tO3A…). We would greatly appreciate your attention and help in sharing it.
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Yingfa Chen retweeted
An open-source 9B model with a 1M-token context and an Apache 2.0 license has just been released on Hugging Face. It’s designed to run on a single consumer-class GPU, such as the NVIDIA RTX 5090. This model breaks the "Compute Wall" and the "Memory Wall," achieving 3.5× faster inference and significantly lower KV-cache overhead compared to dense baselines. This is no longer an "either-or" choice between performance and efficiency. How? Full Attention mechanism's computational complexity grows quadratically with length, making edge-side long-text inference "slow and memory-intensive." Solution: MiniCPM-SALA adopts a golden ratio of 75% Linear Attention + 25% Sparse Attention. MiniCPM-SALA (9B) is OpenBMB’s long-context model aimed at running 1M to 2M tokens on a single GPU without the memory spikes and OOM failures common with dense full attention. The main idea is a sparse plus linear hybrid that keeps long-range recall accurate while keeping cost manageable as context grows. - Architecturally, about 25% of layers use InfLLM-V2 style sparse attention for high-fidelity long-range retrieval, while about 75% use Lightning linear attention, so compute scales close to linearly with sequence length. Instead of a uniform interleave, the sparse layers are placed via a 1:3 layer-selection pattern. - For positional handling and stability, SALA uses hybrid positional encoding (HyPE): RoPE stays in the linear layers but is removed in sparse layers to avoid long-range decay, and it adds QK-normalization plus output gating to improve stability and reduce attention-sink behavior. - Training is done by converting a pretrained Transformer, not training from scratch. It starts from a MiniCPM-4.0 intermediate checkpoint trained on 7T tokens, then applies HALO conversion, keeping the 1st and last layers unconverted and initially training only the converted linear layers. Conversion plus post-training totals about 2T tokens, framed as about a 75% cost reduction versus an 8T scratch run, with context ramping from 512 to 4K, then to 32K, 160K, and 520K, followed by SFT at 64K and 140K. Reported results keep standard performance strong (76.53 average, HumanEval 95.12, AIME24 83.75, AIME25 78.33) While improving long-context behavior (RULER 92.65 at 64K, 89.37 at 128K). It also reports single-GPU 1M-token inference where Qwen3-8B OOMs, 256K TTFT, improving from 180.8s to 51.6s, and RULER holding at 86.3 at 1M and 81.6 at 2M without YaRN. Go to Hugging Face/GitHub to test the model capabilities yourself.
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Yingfa Chen retweeted
I really like this research direction! For a long time, I've been talking about the "brain vs. database" analogy of SSMs vs Transformers. An extension of this that I've mentioned offhand a few times is that I think that the tradeoffs change when we start thinking about building multi-component *systems* rather than single models. For example, if one subscribes to the intuition that modern hybrid models are using the SSM as the main "brain-like" processing unit while the attention is primarily for "database-like" caching to aid with precise retrieval, then I hypothesized that perhaps a more optimal system could be a pure SSM language model combined with explicit external knowledge databases and context caches. This is much more analogous to human-like intelligence that is primarily driven by the brain (an SSM) aided by external knowledge stores (books, the internet) and tool use. This paper shows pretty interesting results that SSMs do seem to have very favorable performance compared to Transformers in this regime of agentic models operating with interactive tool use. Glad to see the intuition validated, and I hope more research continues along these lines!
SSMs promised efficient language modeling for long context, but so far seem to underperform compared to Transformers in many settings. Our new work suggests that this is not a problem with SSMs, but with how we are currently using them. Arxiv: arxiv.org/pdf/2510.14826 🧵
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RNNs suck at context utilization, such as in-context learning and recall, since they compress the context into a small state. Can we improve RNN recall without training from scratch with larger states? We try to answer this question in our latest paper: StateX. (1/n)
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With careful balance of training cost and state size, as well as parameter initialization, the StateX variants of GLA and Mamba 1.3B models see consistent improvements in recall-intensive tasks and in-context learning. (3/n)
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To learn more, please check out our paper: arxiv.org/pdf/2509.22630 (n/n)
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Yingfa Chen retweeted
Many thanks to the Xiaomi MiMo team for contributing the GDN examples :) github.com/tile-ai/tilelang/…
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Yingfa Chen retweeted
🚨 MiniCPM-V 4.0 is here! 🚨 ✨Key features: 🏗️4.1B parameters 🧠Matches GPT-4.1-mini-20250414 on image understanding tasks in OpenCompass evaluation ⚡Runs locally on iPhone 16 Pro Max at 17.9 tokens/sec 69.0 score on OpenCompass (vs 65.2 from MiniCPM-V 2.6 8B) 🚀Small model, good performance 🔥 ⭐GitHub:github.com/OpenBMB/MiniCPM-o 🤗HF:huggingface.co/openbmb/MiniC… #AI #LLM #MLLMs #MiniCPM #EdgeAI
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Yingfa Chen retweeted
cant stop thinking about this one insanely elegant, seems insanely powerful
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Tokenization has been the final barrier to truly end-to-end language models. We developed the H-Net: a hierarchical network that replaces tokenization with a dynamic chunking process directly inside the model, automatically discovering and operating over meaningful units of data
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Yingfa Chen retweeted
The Linear Attention Odyssey: From Imitation to Innovation and Back kexue.fm/archives/11033
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Thanks for sharing our work! I also love this title suggested by @DeanHu11. Any questions/discussions are welcome! xitter.cf/_albertgu/status/18520…
this is a great paper (with a great name) - clever exps on the state capacity and long context ability of SSMs arxiv.org/abs/2410.07145v1 strikingly, for every state size M there's a phase transition at some training context len >= K where SSMs will length-generalize robustly this is because with context length < K, the recurrent state isn't fully utilized and so the model "overfits" during training but once the model's state capacity is fully utilized (by training on long enough seqs), it automatically extrapolates notably, K is linear in M (!) - suggesting there's some notion of intrinsic information content per token (there exists B such that each token in the context corresponds to B bytes of recurrent state). perhaps B is architecture dependent? conversely, worrying about length generalization in recurrent models is probably a red herring. no need to design new mechanisms or special mitigations: just train on longer sequences (which has no computation overhead since linear time!) to generalize better takeaway: stuffing is tasty, and feed your Mambas fully!
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