Daily research notes15 min read

Budgets Shape Geometry; States Compress History

BMuon · Small-scale extrapolation · Async RL · Linear Transformers

Channel budgets, small-model extrapolation, and gradient bias from stale rollouts: seven newly collected research items and technical articles, plus two version records whose substantive changes remain unverified. Original dates are retained; none is presented as first published today. The classic asks how linear attention compresses a growing history into a fixed-size state.

MuonScaling lawsPost-trainingLinear attention
Daily classic · 2020Linear Transformers
Main reading · New paperRead Sections 2–4, Theorem 2, and Appendix E.1

BMuon: hidden channels compete for update budget

BMuon: Budgeting Muon's Spectral Geometry for Structured Compressibility
Rida Assalouh · Tom Jacobs · Rebekka Burkholz · Yani Ioannou · Umut Şimşekli
First posted October 16, 2026, 10:52 EDT · v1

Pruning an MLP channel removes an up-projection row and a down-projection column together. BMuon couples their allocations in update geometry, not through forward gates.[1]

Exact oracle; M denotes momentum, N total channels, and * the nuclear norm
KK={μ∈[0,1]N:∑ℓ,jμjℓ=K},Dℓ=diag⁡(μℓ),μ⋆∈arg⁡max⁡μ∈KK∑ℓ(∥DℓαM1ℓ∥∗+∥M2ℓDℓα∥∗)\mathcal K_K=\{\mu\in[0,1]^N:\textstyle\sum_{\ell,j}\mu_j^\ell=K\},\quad D_\ell=\operatorname{diag}(\mu^\ell),\qquad \mu^\star\in\arg\max_{\mu\in\mathcal K_K}\sum_\ell\left(\|D_\ell^\alpha M_1^\ell\|_*+\|M_2^\ell D_\ell^\alpha\|_*\right)
D uses the optimal allocation; practical training approximates allocation by MM and polar factors by Newton–Schulz
Δ1ℓ=DℓαPolar⁡(DℓαM1ℓ),Δ2ℓ=Polar⁡(M2ℓDℓα)Dℓα,Wiℓ←Wiℓ−ηΔiℓ\Delta_1^\ell=D_\ell^\alpha\operatorname{Polar}(D_\ell^\alpha M_1^\ell),\quad \Delta_2^\ell=\operatorname{Polar}(M_2^\ell D_\ell^\alpha)D_\ell^\alpha,\qquad W_i^\ell\leftarrow W_i^\ell-\eta\Delta_i^\ell
MLP pruningMuon Top-1 (%)BMuon Top-1 (%)
0%75.230 ± 0.02274.174 ± 0.220
70%0.185 ± 0.06274.083 ± 0.324
ViT-S/16 / ImageNet-1K; 150 epochs, batch 4096, 3 seeds; identical magnitude pruning, no recovery training.[1]
Main reading · New paperRead Sections 3–4, Appendices A–B, and experimental tables

Extrapolate relative gaps, not absolute loss

Predictable Scaling: Efficient Model Exploration via Scaling-Law Prediction
Aishwarya Wesanekar · Sheng-Tao Yang · Jiawei Zhang et al.
First posted October 16, 2026, 09:35 EDT · v1

Unlike absolute-loss scaling for language models, this predicts relative gains from changing recommendation architectures, features, or data. NE is cross-entropy divided by label base-rate entropy; 0 indexes the baseline, i a candidate, and j a reduced configuration.[2]

Negative gaps are better; every reported evaluation uses M=1; compare raw proxy, linear regression, and empirical GP
Δi=ℓi−ℓ0ℓ0,di=(Δi(1),…,Δi(M)),Δ^i=fθ(di),E=1n∑i∣Δ^i−Δi∣\Delta_i=\frac{\ell_i-\ell_0}{\ell_0},\quad d_i=(\Delta_i^{(1)},\ldots,\Delta_i^{(M)}),\quad \widehat\Delta_i=f_\theta(d_i),\qquad \mathcal E=\frac1n\sum_i|\widehat\Delta_i-\Delta_i|
Model / held-out candidatesRaw → GP MAE / τAAProxy compute reduction
TS-1 / 140.865 → 0.73888%
FM-1 / 7 (CTR-1)2.150 → 0.70179%
H100; full-scale training uses 80B / 122B samples. τAA is the repeated-baseline noise threshold; cost is estimated from trainers, samples, and throughput.[2]
Main reading · Technical blogRead Sections 1–6 and 10–11: derivation, setup, and payload comparisons

Stale rollouts: zero-mean is not on-policy

Fix a prefix and conditional advantage A. Let q be the generator, pθ the current trainer, and Jθ the logit gradient. The standard score need not have zero mean under q; SFC centers under q instead:[3]

Author's local update; q is fixed and KL constrains drift from the actual generating distribution
s~=Jθ−EqJθ,gq=Eq[As~]=Cov⁡q(A,Jθ),gtotal=gq−β∇θDKL(q∥pθ)\widetilde s=J_\theta-\mathbb E_qJ_\theta,\qquad g_q=\mathbb E_q[A\widetilde s]=\operatorname{Cov}_q(A,J_\theta),\qquad g_{\rm total}=g_q-\beta\nabla_\theta D_{\rm KL}(q\|p_\theta)
Pinsker-based bound in the post; gₚ is a fixed-prefix local update, not the full trajectory gradient
sup⁡a∥(A(a)−EqA)∇θlog⁡pθ(a)∥≤B⟹∥gq−gp∥≤B2DKL(q∥pθ)\sup_a\|(A(a)-\mathbb E_qA)\nabla_\theta\log p_\theta(a)\|\le B\quad\Longrightarrow\quad\|g_q-g_p\|\le B\sqrt{2D_{\rm KL}(q\|p_\theta)}

With Qwen3-0.6B / Countdown, SGD, and 3200 steps, top-16 payload collapsed at step 2992; top-8 plus 8 tail samples at the same width remained stable through completion. Early peak scores miss this failure.[3]

Brief · Inference scalingRead Section 3.3, Section 4, and Appendices A.3–A.4

PONDER: spend extra compute on which positions to revise

PONDER: Learning to Generate in the Right Order
Julius Erbach · Dominik Narnhofer · Bernt Schiele · Jan Eric Lenssen · Konrad Schindler
First posted October 16, 2026, 10:29 EDT · v1

Freeze the generator and train a fill/remove position policy. N empty positions and R removals require N+2R position decisions, not that many backbone calls. For a fixed Sudoku policy trained at R=9, hard accuracy rises from 56.60% at R=0 to 96.68% at R=9 and 98.61% at R=128; evaluation uses 30,000 held-out boards balanced across three difficulty levels. This is not a compute-matched comparison.[4]

Brief · New paperBased on the abstract

Federated Muon: combine local steps with communication compression

Bridging Compressed Communication and Local Steps via Spectral Method in Federated Learning
Dmitriy Bystrov · George Chirkov · Daniil Medyakov · Dmitry Bylinkin · Aleksandr Beznosikov
First posted October 16, 2026, 09:19 EDT · v1

The authors propose a spectral method supporting both local updates and compression, and report convergence without bounded heterogeneity. Full assumptions, compressor details, and communication-round bounds have not been checked; no claim is made for arbitrary client distributions.[5]

Brief · Data mixingBased on the abstract

MaSS: why mixed-domain data can hurt depth estimation

Learning to Discriminate Scene Structures Makes Self-Supervised Depth Learning Scalable
Mengtan Zhang · Yuchuan Cui · Yu Ma · Zizhan Guo · Wei Ye · Rui Fan
First posted October 16, 2026, 11:17 EDT · v1

Separating scene structure from context targets conflicts in mixed-domain training. The authors report separate/joint training on 4 domains and zero-shot evaluation on 8 others. Included under data mixing, not as evidence of a universal fitted power law; matched sample budgets remain unchecked.[6]

Brief · Technical follow-upRead the author's blog; public results were not rerun

A different readout at fixed weights still costs compute

Jebadiah v2.1: two open decision models, where they stand, and how to run them
Jason Brashear / Frontier Infrastructure
Blog October 16, 2026; model released October 10, not a new model release

The author's T1e configuration raises the 27B public-set score from 57.03 to 60.46, while processing about 3.8× as many input tokens and raising mean response time from 247 to 976 ms. The latter is an author-submitted experiment, not a confirmed leaderboard result; do not mix it with the Full metric.[7]

Version record · Changes unverifiedAbstract and version history only; v2/v3 differences not checked

Version record: Reward-Guided Stitching

Test-Time Scaling with Diffusion Language Models via Reward-Guided Stitching
Roy Miles · Aysim Toker · Andreea-Maria Oncescu · Jiankang Deng · Ismail Elezi
First posted February 26, 2026; v3 October 16, 2026, 09:55 EDT

Studies process-reward selection and stitching of intermediate diffusion reasoning steps. This records the in-window version only; neither the method nor abstract metrics are presented as newly added results.[8]

Version record · Changes unverifiedAbstract and version history only; v1/v2 differences not checked

Version record: scaling phases of sparse momentum

Dynamics of Stochastic Momentum with Sparse Updates in High Dimensions
Katie Everett · Elliot Paquette
First posted May 27, 2026; v2 October 16, 2026, 09:22 EDT

Analyzes high-dimensional scaling of sparsity, batch size, and decay via momentum-retention versus learning timescales in sparse-input least squares and rare-class logistic models. This is not a general Transformer theorem; which results are new in v2 remains unverified.[9]

Daily classic · Historical paperRead Sections 3.1–3.4, Algorithm 1, and Section 4.2.1; checked the equation page and Table 1

Linear Transformers: turning history into state

Transformers are RNNs: Fast Autoregressive Transformers with Linear Attention
Angelos Katharopoulos · Apoorv Vyas · Nikolaos Pappas · François Fleuret
First posted June 29, 2020; read the ICML 2020 / PMLR 119 proceedings version
ICML 2020 · Foundational work in linear attention ↗

The Transformer (2017) lets each query retrieve the entire history, with a growing cache. This ICML 2020 work uses finite-dimensional kernel features to compress history into a matrix state: it changes the attention kernel rather than obtaining exact softmax at no cost.[10][11]

q and k are queries/keys, v∈ℝᵈᵛ; positive features ensure a positive denominator. This is the experimental kernel
ϕ:Rdk→Rm,ϕ(x)=ELU⁡(x)+1,yt=∑j≤tϕ(kj)⊤ϕ(qt)vj∑j≤tϕ(kj)⊤ϕ(qt)\phi:\mathbb R^{d_k}\to\mathbb R^m,\quad \phi(x)=\operatorname{ELU}(x)+1,\qquad y_t=\frac{\sum_{j\le t}\phi(k_j)^\top\phi(q_t)v_j}{\sum_{j\le t}\phi(k_j)^\top\phi(q_t)}
Equations (9)–(12), rewritten in column-vector notation: aggregate KV before answering queries
St=∑j≤tϕ(kj)vj⊤∈Rm×dv,zt=∑j≤tϕ(kj),yt=St⊤ϕ(qt)zt⊤ϕ(qt)S_t=\sum_{j\le t}\phi(k_j)v_j^\top\in\mathbb R^{m\times d_v},\quad z_t=\sum_{j\le t}\phi(k_j),\qquad y_t=\frac{S_t^\top\phi(q_t)}{z_t^\top\phi(q_t)}
S₀=z₀=0; at fixed feature dimensions, inference state is independent of sequence length (excluding projections and other layers)
St=St−1+ϕ(kt)vt⊤,zt=zt−1+ϕ(kt),time/token=O(mdv),state=O(mdv+m)S_t=S_{t-1}+\phi(k_t)v_t^\top,\quad z_t=z_{t-1}+\phi(k_t),\qquad \mathrm{time/token}=O(md_v),\quad\mathrm{state}=O(md_v+m)

Training need not cache every prefix matrix either. For unnormalized outputs, let g be the incoming gradient; prefix/suffix scans give:[10]

Numerator gradients from equations (13)–(15); differentiate the denominator separately. Constant scan accumulators do not mean constant total training activations
yˉt=St⊤ϕ(qt),gt=∇yˉtL,Tj=∑t≥jϕ(qt)gt⊤;∇ϕ(qt)L=Stgt,∇ϕ(kj)L=Tjvj,∇vjL=Tj⊤ϕ(kj)\bar y_t=S_t^\top\phi(q_t),\quad g_t=\nabla_{\bar y_t}\mathcal L,\quad T_j=\sum_{t\ge j}\phi(q_t)g_t^\top;\qquad \nabla_{\phi(q_t)}\mathcal L=S_tg_t,\quad \nabla_{\phi(k_j)}\mathcal L=T_jv_j,\quad \nabla_{v_j}\mathcal L=T_j^\top\phi(k_j)
Autoregressive MNISTbits/dim ↓
Softmax0.621
Linear0.644
Table 1; 8 layers, 8 heads, width 256, RAdam, 250 epochs, training batch 10. Changing the kernel is not lossless; historical implementation speedups are not extrapolated to modern hardware.[10]

READ THE ORIGINALS

Original sources

  1. BMuon v1: method, theory, and pruning setup
  2. Predictable Scaling v1: prediction and resource budgets
  3. Yihua Zhang: SFC + Trainer–Generator KL (October 16, 2026)
  4. PONDER v1: budgets, experiments, and appendix
  5. Federated spectral method v1: abstract and original date
  6. MaSS v1: abstract and original date
  7. Jebadiah: author's readout experiment and cost
  8. Reward-Guided Stitching: v3 and version history
  9. Sparse Momentum: v2 and version history
  10. Historical reading: Linear Transformers, ICML 2020 full paper
  11. Background: Attention Is All You Need (2017)
  12. Classic selection: official ICML 2020 proceedings record
Search window

October 16, 2026 08:57 — October 19, 2026 08:57 · America/New_York

READ · THINK · DISCUSS

Discussion & likes

Discuss a derivation, add a reference, or suggest the next classic.

Comment, reply, or like below. Sign in with GitHub to participate; comments are public.

Loading discussion…

Open discussion on GitHub ↗

← Back to all issues