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Attention

The Work a Verifier Needs

A certified int8 output head picks the same token as the engine’s, recomputing about 1.8 vocabulary entries per decision.

On one GH200, Qwen3.5-4B throughput rises 1.3–4.6% over tuned stock SGLang at one request, and the fastest setup is 1.0–3.0% slower at 2 to 8 requests at once. The guarantee assumes a tested but unproved error model of the production kernel.

Details

An int8 copy of the LM head bounds every vocabulary score. The head recomputes only the entries that could win and falls back to the engine’s head when the bounds leave the token undecided.

Every token matches the engine head on the same batch in replay and when served beside the stock head. Drafter-head bounds skip almost no vocabulary in the tested variants.

The certification theorem assumes a tested but unproved error model of the closed-source production kernel.

Near-Linear Attention in Three Dimensions

A randomized algorithm computes three-dimensional softmax attention in near-linear word-RAM time, which gives the optimal exponent.

The inputs are logarithmic-bit rational coordinates bounded by n¹⁰ and scalar values in [−1, 1], with simultaneous additive error at most n⁻¹⁰.

Details

Small sampled hulls organize keys into simplicial normal cones. Dyadic bins share moment sums across queries, while conflict sets recurse; reconstruction uses exact integer arithmetic.

A time cutoff gives the error and running-time guarantee with probability at least 2/3. Without a cutoff, every execution meets the error bound and the running-time bound holds in expectation.

A Lean formalization (103 audited theorems) proves Lemmas 4.1 and 5.1 and parts of Lemmas 2.1–3.2 and 4.2. Facts about the sampled hull enter as hypotheses, and the assembly into Theorem 1.1 is not formalized.

An I/O Lower Bound for Exact Attention

Exact softmax attention needs Ω(nd + n²/M) memory transfers in a real-arithmetic model.

It covers bounded deterministic programs using +, −, ×, ÷ and exp, with n, d ≥ 2 and an M-word cache where M ≥ d².

Details

A proof counts algebraically independent kernel ratios recoverable from output derivatives. Each cache epoch contributes only a bounded number of Jacobian generators, even with recomputation and finite branching.

Theorem 5.5 proves Ω(nd + n²d²/M) transfers when every exponential argument is a polynomial in the full dot-product scores, including mixtures that form no individual score.

Lean 4 proofs cover Lemmas 2.1, 2.2, 4.1, 5.1 and 5.4 and Theorem 5.2. The passage from a program to its trace and the transfer counts of the constructions are not formalized. Field containment alone does not give uniform dependence on d: a Strassen-based prefix reaches the full attention coefficient field in o(nd + n²d/M) transfers on a parameter sequence while computing only an auxiliary vector.

Exact Sampling from Neural Networks: Depth, Attention, and Decoding

Exact autoregressive sampling with an appendable attention index has expected polylogarithmic context cost under fixed-rank key geometry.

Each layer’s keys must share one affine space of fixed dimension, with positive RMSNorm stabilizers. There’s no GPU implementation, and at the large ranks of ordinary models the bounds predict no useful speed.

Details

For tanh networks with zero biases and absolute row sums at most one, the expected number of input queries scales as the square root of depth at each fixed first-layer rank. A uniformly bounded column envelope gives the same scale at any rank, in the logarithmic-depth, finite-precision regime.

The decoder's outputs follow the original autoregressive law exactly. Fixed-rank depth sharpness requires sufficient width and coefficient precision; the unrestricted square-root versus linear query gap remains open.

These bounds give no useful speed prediction at the large ranks of ordinary models. Lean checks some theorems in full and, for others, the analytic core or the closing arithmetic under stated hypotheses. Bit complexity, preprocessing, storage and runtime are not formalized.

A reachable-state separation between attention compression and its certificates

Attention outputs can have compact approximations while one class of certificates still needs many cached rows.

The checker that passes evaluates the dense reference and is slower than dense decoding.

Details

The paper compares how far attention can be compressed with what a certificate needs to read, using reachable states of frozen SmolLM2-135M.

At a 7,168-token prompt, exact packing witnesses for the certificate need at least 28.88% of dense final-layer interactions. A concrete tenfold grouping has a checked one-intervention sequence total variation of 1.148 × 10⁻⁵.

The public replay and arithmetic checks pass. Lean checks six supporting arithmetic lemmas; the main argument and the PyTorch code are outside the formalization.

StateCut

Exact row counts let a cached summary certify some attention results without reading the rows.

On captured model runs, no complete attention call is certified. StateCut has no pretrained speedup and no proof it matches a deployed attention backend.

Details

When can a summary certify an attention result without reading every cached row? StateCut sharpens the bounds with exact row counts, refines inconclusive summaries in a persistent forest, and makes decoder writes transactional. Results are checked against an explicit numerical reference.

The checks include 66 Lean theorems and 68,851 GPU arithmetic cases. In small synthetic examples, the finite-count bounds avoid raw-row reads.

Synthetic finite-count ablation: at score magnitude 0.13, input sizes 3, 5, 9, and 17 need no raw-row reads; sizes 33 and 65 fall back to all rows. At magnitude 0.15 only sizes 3 and 5 avoid reads. The chord bound reads every row in all these cases.
Finite counts help on small synthetic cases, then fall back as counts grow. One summary, no refinement; initial summary construction is excluded. All plotted outputs match the dense E24 reference. Source data

Contracted Moment Kernels

Moment summaries certify some attention outputs in constructed cases.

No coordinate passes on the trained Qwen trace. Every measured complete GPU path is slower than fused dense attention.

Details

The paper asks what compressed moment information can determine about attention outputs. It combines exact boundary certificates, value coupling, rational test cases, and GPU measurements that include the cost of decisions and fallback.

Coupled bounds accept 61 of 149 initial coordinates in the constructed rational suite, versus 57 for independent boxes.

Initially accepted coordinates out of 149: global value hull 50, independent boxes 57, coupled blocks 61, across 53 exact-rational constructed cases.
Four more coordinates pass with coupling than with boxes. The global hull already accounts for three of them, leaving one gain beyond the hull. Constructed cases do not estimate trained-model coverage. Source data

Learning theory

Learning-guided sampling

For a specified finite class, one-sided safe guidance can cost linearly many queries where pointwise guidance needs logarithmically many.

The safe-guide results assume bounded stopped reciprocal capacity.

Details

Sampling from an unknown member of a known finite class using approximate prefix masses, with every query to the guide charged.

Under pointwise guidance with factor 9/4 and error 1/16, worst-case query complexity is min{M, n√(log M), n²} up to logarithms. A known background plus an unknown atom has a matching worst-case rate over backgrounds at error at most α/4; a uniform background permits a sharper rate.

Lean 4 formalizes the numbered results with the cited finite-class upper bound taken as an explicit hypothesis. The general fixed-error finite-class gap remains open.

Distribution-independent SQ learning does not imply low dimension complexity

Distribution-independent SQ learning is exponentially separated from ordinary, exact probabilistic and expected-error dimension. Patel (2026) independently posted a separation first, and a qualitative one follows from earlier results.

The learner is polynomial in the explicit table’s size, and I don’t claim that for input length. Lean checks only supporting lemmas.

Details

A rectangle-based learner uses logarithmically many statistical queries at constant tolerance, while the same classes require dimension linear in the construction scale.

The dimension lower bound survives allowing the feature law to depend on a known target prior and discarding any fixed fraction of targets below one. The classes also give a counterexample to the stated representation bound in Karchmer and Malach’s Theorem 4.1, whose proof Feldman et al. (2026) had already reported as flawed.

The counterexample does not disprove Karchmer and Malach’s broader mini-batch SGD conclusion.

Bounded-Time Logistic SGD Requires Gaussian ReLU Kernel Correlation

At bounded effective time, label correlation with a fixed Gaussian ReLU feature map controls logistic SGD’s expected error.

Requires bias-free two-layer ReLU networks on Boolean-cube inputs, Gaussian initialization, exact single-example updates, tail-sum prediction, effective time ηmT ≤ 12, and large enough width and step count.

Details

The paper studies exact single-example logistic SGD on a two-layer bias-free ReLU network, with Gaussian initialization and tail-sum prediction. Learning to error below one-half under every input marginal forces a kernel margin.

The kernel margin yields VC-dimension and deterministic representation bounds. Above an explicit dimension threshold, only constant targets can be learned under every marginal. Separate results cover parity and fixed-gate updates.

Lean checks the risk bound, margin theorem and fixed-gate theorem, except the final random-projection step. The other results are proved in the paper.

Learning Low-Logit-Rank Distributions from Conditional Samples

At every fixed logit rank, chosen-prefix next-bit samples suffice to learn an accurate standalone generator in polynomial time.

Distributions must be fully supported on T bits, with centered next-bit logits of magnitude at most T and rank at most d at every history cut. The learner may query any prefix.

Details

Fair-bit noise smooths rare events, a polynomial approximates the transformed logits, and a robust logit learner runs on a cached sampling simulation. A second proof uses a surrogate with low probability rank.

At fixed accuracy and confidence, the bound on submitted and generated tokens has degree 6d + 15 in T, up to logarithmic factors and rank-dependent constants. A supplied inverse-polynomial conditional-probability floor permits joint polynomial learning in T and d. If the rank can grow, no learner is polynomial in both T and d, assuming strong pseudorandom functions computable by logarithmic-depth circuits once the key is fixed.

Numerical logit simulation can require exponentially many samples even at rank one. Lean takes the cited learning and compilation guarantees as hypotheses and does not cover the pseudorandom-function assumption, the coupling of cached estimates, running time or bit complexity.

Certified Accounting for Adaptive Shuffled Gaussian Training

It certifies privacy accounting for multi-epoch shuffled Gaussian training, including the full adaptive transcript.

Data are shuffled once per epoch into fixed-size batches, and each query may depend on all earlier releases.

Details

A null-clone reduction bounds likelihood sums by candidate count and constructs a finite rational dominating pair that composes across epochs. The accountant allows heterogeneous items and queries that adapt to earlier releases.

For 1,000 batches per epoch, five epochs, noise multiplier 1 and δ = 10⁻⁸, the worst-case ε lies in (6.423, 7.97]; matched Poisson sampling is certified at 0.507. An adaptive counterexample shows that the pair Chua et al. conjectured to dominate all adaptive queries does not.

Lean covers the dominating-pair construction, counterexample and supporting certificate lemmas. The reduction and other stated steps remain in the written proofs.

Witness-CL

This SQL agent memory reuses a relation learned from correct queries only after a later task confirms it.

Transfer and retention gains aren’t shown yet, and the larger pilot is unfinished.

Details

A SQL agent learns reusable relations from correct queries, corroborates them on later tasks, and executes them in new computations without updating model weights.

A 240-episode diagnostic used 40.9% fewer tokens than full history, but 115.4% more than the ACE baseline, with every arm at the accuracy ceiling.

Physics

Memory return in quantum machines

Returning a quantum memory’s reduced state does not mean it can supply fresh independent randomness.

Covers closed machines with exact or approximate return of that state.

Details

The paper studies closed quantum machines that transform fresh inputs while returning their memory to its initial state, including exact and approximate return and repeated use of the coherent quantum homogenizer.

Exact memory return prevents a closed machine from purifying maximally mixed inputs. With return tolerance δ, exact purification of n qubits needs n/δ + O(n) memory qubits, while independent randomization needs only ⌈n/2⌉. For the coherent quantum homogenizer, requiring independent outputs and return after every use forces ϵ + δ/2 ≥ 1/4.

Lean proofs cover the soundness of the disjoint-gate exchange certificates and the first-use step of Proposition 14.

Mechanical mediation through shared apparatus in gravitational-entanglement experiments

A shared support can entangle two interferometers. Force replay and response bounds give a test for ruling that channel out.

Applies to a linear Gaussian apparatus. The mounting example is modeled; no instrument was measured.

Details

Two force-weighted cross responses bound the spin channel through the shared support. Classical force replay measures the bound, and local pulse changes can null both responses.

When gravity acts mainly during a hold, the permissible pulse-weighted compliance scales as the cube of the ramp time. A modeled clamped horizontal link gives a phase comparable to a millisecond-ramp gravitational reference and a negligible one for long ramps.

The calculations are checked by 57 unit tests and two interval checks.

From information tasks to exclusivity and Bell bounds

Information tasks give a conditional Bell bound. Added capacity and measurement requirements recover the quantum value.

It also assumes the capacity bound and reversible setting interchange.

Details

The paper derives consistent exclusivity and Bell bounds from information tasks, without assuming a quantum state space in the task proofs.

Completing two-copy parity measurements with an “other” outcome gives a Bell bound controlled by the weights of the residual records. No-hypersignaling supplies the capacity bound when the relevant preparations are accessible and local signaling dimensions match the label counts.

The examples and certificates pass 1,276 exact finite checks. The general task arguments are proved in the text.

Comparison, coherence and the stability of constructor entropy

An entropy-preserving task is possible exactly when a uniform work bound holds along a vanishing-noise family. A stationary quantum model realizes the entropy order.

It changes the task clauses and adds an explicit quantum completion.

Details

Do finite work and heat tasks determine a single additive entropy? The paper studies a modified pair-task formulation with sharp work stores and exact return of the machine’s memory marginal.

In an energy-conserving quantum completion, mean energy and von Neumann entropy determine closed tasks, and entropy alone determines work-assisted tasks. A known no-broadcasting theorem excludes coherence between distinct energies when comparison and convexity are required.

The construction gives one entropy model. The paper does not show that every compatible dynamics has the same entropy order. Both finite programs pass their classical and exact quantum checks.

Lean formalizations

Erdős problems

Supporting results and constructions for Erdős problems 20, 61, 119, and 885, formalized in Lean 4 and mathlib.

Partial results and unfinished proof developments; the main conjectures remain open.

Mathematical notes

Systems studies

Command A+ on two H100s

vLLM · 91 runs · random-token workloads

I gave the KV cache the memory vLLM left unused. Capacity rose 1.79x, and end-to-end throughput rose 4–34% at each context length’s largest batch.

Results & scope

One 2×H100 node, random-token workloads.

At 8K context and batch 10, a 2,048-token prefill chunk cuts p99 inter-token latency from 754 ms to 222 ms and costs 18% of single-request prefill throughput.

The sweep separates memory-capacity limits, decode behavior, and stalls caused by concurrent prefill. All 91 recorded runs complete without preemption.

The report keeps steady-state rates separate from end-to-end throughput. Model quality with an FP8 KV cache was not evaluated.

The 25–82% steady-state decode gains come mainly from larger batches at each configuration’s capacity.

H100 serving estimator

Estimates GPU time per request from 91 vLLM runs on two H100s.

6.5% median error on 14 held-out runs, against 8.6% for a token-rate baseline. The baseline wins on the unseen configuration.

Results & scope

One checkpoint on one 2×H100 stack.

The split groups related prompt/output/batch configurations before fitting, keeping the final 14-row test set separate from training and validation.

The artifact includes predictions, interval diagnostics, calibration data, and a separately written verifier that recomputes the saved metrics. No one outside the study has replicated it.

On the 12 unseen-configuration runs, the token-rate baseline has 6.5% median error against the model’s 14.6%. Test-set interval coverage is 64.3% against a nominal 80%.

Tensor parallel reference

A decoder block split across 1, 2 and 4 local CPU processes, with numerical checks and exact communication counts.

All 192 executions ran clean, and all 96 injected faults were contained.

Results & scope

Local CPU processes over loopback TCP.

The largest relative L2 error in clean cases is 4.64 × 10⁻⁸. The recorded protocol accounts exactly for all 8,512 frames.

Faults target handshake, attention, and MLP phases. In all 96 cases the coordinator produces no output and no worker survives.

The study checks correctness and fault handling only.

SmolLM2 conformance

Separate full-sequence and KV-cache implementations of SmolLM2-135M, checked layer by layer on CPU.

It ran 48 cases and 1,440 layer comparisons and localized all 7 injected faults.

Results & scope

Float32 on CPU, a pinned SmolLM2-135M revision, and two short hand-written inputs.

The independent paths cover RMSNorm, RoPE, attention, MLP execution, logits, and incremental K/V state. All 24 greedy tokens match and the forward cases have zero top-1 disagreements.

Each of the seven injected faults is traced to the first layer it affects.

Public repositories