Daily research notes18 min read

Norm growth and environment composition

MuonGS · SynthAPI · MoMuSAM · Reading Performer

Three main readings and four briefs: accumulated effective step sizes, composition-aware agent scaling, and momentum as a perturbation probe. The classic explains positive random features for softmax attention.

MuonScaling lawsPost-trainingRNN / linear attention
Daily classic · 2021Performer
Main readingRead relevant main-text methods and results; no code replication

Accumulation over late windows

MuonGS: Pretraining LLMs with Relaxed Weight-Norm Control
Athanasios Glentis · Dawei Li · Mingyi Hong
First posted 2026-10-27 · v1

Let r_t be the Frobenius weight norm and O_t a Muon direction with norm at most √p, p=min(m,n). The paper studies entire trajectories rather than a single normalized step. Its accumulated effective learning rate bounds relative displacement over any later interval.[1]

Nonzero iterates; vanilla bounded-direction update [1]
rt=∥Wt∥F,CT=∑t<Tηtrt,∥WT−Ws∥Fmax⁡(rs,rT)≤p(CT−Cs)r_t=\|W_t\|_F,\quad C_T=\sum_{t<T}{\eta_t\over r_t},\qquad {\|W_T-W_s\|_F\over\max(r_s,r_T)}\le\sqrt p(C_T-C_s)

MuonGS removes the radial component after orthogonalization. Orthogonality to W_t eliminates the term linear in the step size in squared-norm growth.[1]

Algorithm 1 and Proposition 4.1 [1]
O~t=Ot−⟨Wt,Ot⟩Frt2Wt,Wt+1=Wt−ηtO~t,rT2≤r02+p∑t<Tηt2\widetilde O_t=O_t-{\langle W_t,O_t\rangle_F\over r_t^2}W_t,\quad W_{t+1}=W_t-\eta_t\widetilde O_t,\quad r_T^2\le r_0^2+p\sum_{t<T}\eta_t^2
A growing late-window budget; not a sufficient condition for learning [1]
ηt≡η>0:rt=O(t),C2T−CT=Ω(T)\eta_t\equiv\eta>0:\qquad r_t=O(\sqrt t),\quad C_{2T}-C_T=\Omega(\sqrt T)
Model / dataBudgetComparison / metric
GPT-160M / 400M · FineWeb3–25B / 8–63B tokensMuonGS vs MuonH, MuonW; validation CE/PPL
Main readingRead relevant main-text methods and results; no code replication

Data composition moves the ceiling

Scaling Laws for Tool-Use Agents via Controllable Environment Synthesis
Andrew Szot · Samira Abnar · Omar Attia · Abbas Kazerouni · Michael Kirchhof · Cheng-Yu Hsieh · Raviteja Vemulapalli · Alexander Toshev
First posted 2026-10-27 · v1

SynthAPI separates apps A, tasks per app T, profiles per task S, and profile complexity D. Following token-based scaling (Kaplan 2020; Chinchilla 2022, background), it models normalized downstream success from environment composition; T here counts tasks, not optimizer steps.[2]

Empirical fit, separately by model size M; σ is logistic [2]
N=ATS,P^M(A,T,S,D)=σ(c0+cAlog⁡2(ASD)) σ(b0+bTlog⁡2T)νN=ATS,\quad \widehat P_M(A,T,S,D)=\sigma(c_0+c_A\log_2(ASD))\,\sigma(b_0+b_T\log_2T)^\nu

P averages gains over the base model after benchmark-specific normalization by the best observed gain. It is not raw accuracy. More apps and database diversity raise the fitted ceiling; tasks per app control approach to it.[2]

Design(A,T,S,D)Task count
SubOpt(32,1024,1,2)32,768
Opt(64,128,4,4)32,768
Held-out top 25% of training FLOPs, normalized score [2]
MAEcomposition=0.0285,MAEquantity=0.1706\mathrm{MAE}_{\rm composition}=0.0285,\qquad\mathrm{MAE}_{\rm quantity}=0.1706
Main readingRead relevant main-text methods and results; no code replication

Momentum probes the neighborhood

Sharpness-Aware Muon: Matrix-Aware Optimization with Momentum-Guided Perturbations
Zhiwei Zhai · Wenjing Yan · Ying-Jun Angela Zhang
First posted 2026-10-27 · v1

MuSAM inserts a SAM-style local perturbation before the Muon update. MoMuSAM replaces the current clean gradient used to construct that perturbation with the previous momentum, removing one gradient evaluation.[3]

Local minimax objective and its momentum-guided heuristic [3]
min⁡Wmax⁡∥δ∥F≤ρf(W+δ),δtMo=ρMt−1∥Mt−1∥F\min_W\max_{\|\delta\|_F\le\rho}f(W+\delta),\qquad \delta_t^{\rm Mo}=\rho{M_{t-1}\over\|M_{t-1}\|_F}
Ideal polar notation; implementation uses Newton–Schulz [3]
Mt=μMt−1+(1−μ)∇ℓ(Wt−1+δt;Bt),Wt=Wt−1−ηPolar⁡(Mt)M_t=\mu M_{t-1}+(1-\mu)\nabla\ell(W_{t-1}+\delta_t;\mathcal B_t),\quad W_t=W_{t-1}-\eta\operatorname{Polar}(M_t)
MethodGradient evaluations / stepStationarity order
MuSAM2O(T^{-1/4})
MoMuSAM1O(T^{-1/4})
BriefAbstract only

LinMix: Data Mixing as Linear Domain Attribution

LinMix: Data Mixing as Linear Domain Attribution
Hubert Baniecki · Przemyslaw Biecek · Martin Pawelczyk
First posted 2026-10-27 · v1

Abstract only: vertex sampling on a capped simplex improves the design matrix for linear domain attribution, replacing concentrated Dirichlet mixtures. The fitted attribution selects a data mixture; this is proxy-based weighting, not adaptive data collection.[4]

BriefAbstract only

Does LLM Pre-Training Typically Occur at the Edge of Stability?

Does LLM Pre-Training Typically Occur at the Edge of Stability?
Yuhang Cai · Haodong Wen · Haofeng Huang · Deyi Liu · Yiyuan Ma · Kaifeng Lyu
First posted 2026-10-27 · v1

Abstract only: persistent negative curvature makes local quadratic dynamics diverge at every positive learning rate (Edge of Convexity). After separating this effect, EoS is prevalent but not universal in pretraining up to 787M, disappearing at sufficiently small learning rates or batch sizes. This is Kaifeng Lyu author-subscription news.[5]

BriefAbstract only

EnergyCal: Taming Loss Spikes in Muon-Family Optimizers for Sparse MoE Training

Primary abstract checked: EnergyCal calibrates update energy in sparse-MoE Muon-family optimization to address loss spikes. Full algorithm and controlled ablations were not reviewed; no general speed or stability claim is inferred.[6]

BriefRead experiments and caveats

Unlearnability in RLVR: What More Samples Reveal About Hard Tasks

Unlearnability in RLVR: What More Samples Reveal About Hard Tasks
Chinmaya Andukuri · Guga Gogia
Technical blog · 2026-10-27

Technical blog, read experiment and caveats: Qwen2.5-0.5B, MATH levels 1–4, 100 GRPO steps, two seeds; evaluation increases from 8 to 256 attempts. About 20% of prompts initially solved 0/256 times later exceed 10%. Zero observed successes is not zero probability; finite-horizon “stuck” is not impossibility.[7]

Historical classicRead feature identities, reassociation, causal prefix sums and theoretical scope; proofs not fully audited

Positive features before normalization

Rethinking Attention with Performers
Krzysztof Choromanski et al.
First posted 2020-09-30; read v4 (2022-11-19), §§2–3 and Appendix B.1
ICLR 2021 · important historical work in linear attention ↗

After random Fourier features (Rahimi–Recht, 2007) and Linear Transformers (2020), Performer targets the original softmax kernel rather than merely replacing it. Absorb d^{-1/4} into queries and keys, so a_ij=exp(q_iᵀk_j).[8][9]

Gaussian moment-generating identity; Lemma 1 [8]
ϕω(x)=exp⁡(ω⊤x−∥x∥2/2),ω∼N(0,I),E[ϕω(x)ϕω(y)]=ex⊤y\phi_\omega(x)=\exp(\omega^\top x-\|x\|^2/2),\quad\omega\sim N(0,I),\quad\mathbb E[\phi_\omega(x)\phi_\omega(y)]=e^{x^\top y}
Unbiased kernel estimator with positive features [8]
ϕ(x)=m−1/2(ϕω1(x),…,ϕωm(x)),a^ij=ϕ(qi)⊤ϕ(kj)≥0\phi(x)=m^{-1/2}(\phi_{\omega_1}(x),\ldots,\phi_{\omega_m}(x)),\quad \widehat a_{ij}=\phi(q_i)^\top\phi(k_j)\ge0

Positivity avoids negative normalization sums. Orthogonal directions, while preserving Gaussian marginals, further reduce kernel-estimator variance. Kernel unbiasedness does not imply unbiasedness after taking a ratio.[8]

Reassociate products; no L×L attention matrix [8]
Y^=diag⁡(Qf(Kf⊤1))−1Qf(Kf⊤V),time=O(Lmdv)\widehat Y=\operatorname{diag}(Q_f(K_f^\top\mathbf1))^{-1}Q_f(K_f^\top V),\qquad \mathrm{time}=O(Lmd_v)
Causal recurrence, fixed m and value dimension; Appendix B.1 [8]
St=St−1+ϕ(kt)vt⊤,zt=zt−1+ϕ(kt),y^t=ϕ(qt)⊤Stϕ(qt)⊤ztS_t=S_{t-1}+\phi(k_t)v_t^\top,\quad z_t=z_{t-1}+\phi(k_t),\qquad \widehat y_t={\phi(q_t)^\top S_t\over\phi(q_t)^\top z_t}

READ THE ORIGINALS

Original sources

  1. MuonGS: Pretraining LLMs with Relaxed Weight-Norm Control
  2. Scaling Laws for Tool-Use Agents via Controllable Environment Synthesis
  3. Sharpness-Aware Muon: Matrix-Aware Optimization with Momentum-Guided Perturbations
  4. LinMix: Data Mixing as Linear Domain Attribution
  5. Does LLM Pre-Training Typically Occur at the Edge of Stability?
  6. EnergyCal: Taming Loss Spikes in Muon-Family Optimizers for Sparse MoE Training
  7. Unlearnability in RLVR: What More Samples Reveal About Hard Tasks
  8. Performer · full text
  9. DBLP · ICLR 2021 record
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2026-10-25 08:22 — 2026-10-28 08:22 · America/New_York

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