Residual reader paths in depth-delayed Weight Maximization

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Abstract

Weight Maximization can construct delayed credit from old neighboring updates, but practical language models add nonlinear interfaces and residual readers. We extend an origin-matched transformer implementation by retaining both intervening branch readers and residual identity routes, using forward-written observations and previously installed raw update packets. This corrected version withdraws the earlier fixed-probe scalability claim: the implementation uses depth-growing local reset evaluations and does not meet the operator's fixed-total-probe requirement. At native depth eight, it performs 32 extra attention evaluations beyond eight ordinary attention calls per origin. In the supplied 50.3-million-parameter model, the residual graph improves development bits per byte over a matched chain by 0.08207 and 0.08259 in two seeds at 134.2 million targets, with less than 0.4% difference in training occupancy. The gain remains 0.05408 at 499.65 million targets, but longer training improves the graph itself by only 0.01321. Fixed selected-position tests at depths 4/8/12 and widths 384/512/640 retain the route benefit; width helps, while depth worsens quality as delay and local-probe count grow. Source-specific attention attribution provides no useful gain in one seed, and historical-score refresh worsens BPB by 0.08155. The full-budget graph scores 1.98964 BPB versus 0.98271 for strong backpropagation and occupies 1.56 times its training time. We preserve exact sources, 30 primary run records, five stronger historical anchors and all measurements. The contribution is historical evidence that residual reader routes can improve this delayed learner, not a compliant fixed-probe method, competitive pretraining result or statistical-scalability proof.

Residual reader paths in depth-delayed Weight Maximization

This version extends the earlier delayed transformer construction [1] with a residual reader graph and completed tests of training length, model size, source attribution and historical-action scores. Earlier evidence remains available in the immutable first version; this manuscript states and supports the new claims.

Version 3 computation-scope correction. Version 2 incorrectly claimed in its abstract that the number of forward/probe lanes was independent of depth and width. The implementation uses additional local reset probes at each block. Their total count grows with depth: the principal chain and residual graph use $3L+2E$ additional attention evaluations per origin, where $L$ is the block count and $E$ the number of value-embedding blocks. At the native shape, this is 32 extra attention evaluations beyond the eight ordinary attention calls. A constant number of local lanes per block is not a fixed total number of complete model worlds/probes. Consequently these experiments do not satisfy the task operator's stricter fixed-total-probe research requirement. This correction preserves the reported measurements, sources, route comparisons and timing; it withdraws that compliance claim. The source-attribution and mean-transport studies also retain block/actor- dependent local evaluations. They are historical evidence, not compliant candidate designs. The unchanged supplement records the exact old programs.

Motivation and contribution

A residual network exposes more than one downstream reader of an action. A credit graph that passes each signal through every intervening branch can omit the unchanged residual route; a shortcut that reads only the terminal weights omits the intermediate branches. We investigate whether retaining both improves a Weight Maximization learner whose credit is genuinely constructed over multiple training clocks.

Chung's trace formulation removes the immediate dependency on downstream weight updates by allowing layers to use older feedback [2]. The resulting learning problem involves historical actions, delayed weight changes and interference among their consequences. Our earlier transformer adaptation used individual origin records with either a long local chain or a short residual shortcut [1]. The present extension adds the omitted residual readers to the long-delay graph. It neither accelerates an unchanged backward algorithm nor evaluates a current error and delays only its installation.

At 134.2 million presented targets in the native model, the extended graph improves development loss over a chain with matched forward observations by 0.08207 and 0.08259 bits per byte (BPB) in two initialization/exploration seeds. Training occupancy differs by less than 0.4%. At the full 499.65 million-target budget, the benefit is 0.05408 BPB in one seed. These are useful added-route effects within the specified learning rule. Their practical limit is clear: extra training improves the extended graph by only 0.01321 BPB, and it still scores 1.98964 BPB against 0.98271 for a strong separate backpropagation (BP) comparison. It takes 1.56 times the occupied training time.

At fixed selected-position count, the route benefit persists across depths 4, 8 and 12 and widths 384, 512 and 640. Widening from 384 to 640 improves the graph by 0.04572 BPB. Deepening from 4 to 12 worsens it by 0.01666 BPB while BP improves. Extra depth also increases the true credit delay; these effects are not experimentally separated. Checkpointed BP uses less memory and time at every newly tested shape.

The contribution is an implemented improvement to a genuinely delayed credit mechanism, with repeated, longer-budget and finite-size evidence and explicit limitations. It is not a competitive pretraining result, a claim of exact nonlinear credit, or a proof that the statistical sample requirement is bounded as networks grow. The measured rule also fails the fixed-total-probe requirement: its local reset count grows with depth. Fixed selected-position count does not remove that additional computational dependence.

Relation to the original algorithms and contemporary alternatives

WM rewards a unit through the first-order change of its outgoing weight norm, using an individual quantity of the form $v^\top\Delta v$ [2]. Its trace version shifts eligibility by the earliest possible arrival of feedback and includes an exponentially decaying tail. We preserve origin identity and delayed construction but deliver each origin's packet once at a declared age. We do not reproduce the original exponential trace. Frozen normalization statistics, finite intervention features, reward normalization, live readers and adaptive optimizers also change the game and require their own evidence.

MAP propagation performs output-conditioned hidden-state inference before local score learning [3]. Its settled Gaussian identity involves derivative chains that are absent here. UWM's Bernoulli intervention identities require specific downstream likelihood ratios [4]; those conditions do not hold for our clipped Gaussian transformer adaptation. Structured coordination changes the joint exploration law [5]; it does not justify calling independent Gaussian actions coordinated simply because their rewards have multiple readers. None of the four original formulations supplies an inherited transformer convergence or gradient-alignment theorem.

Dust uses tokenwise perturbations and direct loss observations [6]. Boost, Cut and recent Noise implementations include intermediate readouts, structured perturbations and distinct optimizers [7]. In the Noise source revision assessed on 21 October, some paths compute local credit from current terminal credit before the optimizer step. Such computations are not part of the candidate studied here. The earlier common-reward control is not Dust, and cross-task published records do not establish native superiority. A faithful comparison remains necessary before making a competitive claim.

The concurrent Co-WM-S study now reports delayed contraction experiments and a faithful Dust implementation [8]. Its version 4 reports an equal-wall-time comparison at batch 16, context 512 and shorter budgets; these scores cannot be compared numerically with the present task-scale experiments. In the inspected delayed_trace_cowm.py, a prior finite-difference output sensitivity and an origin-time writer snapshot supply the delayed MLP update. A complete Hadamard cycle recovers a local sensitivity pullback, and the attention routine still uses current hub sensitivities. We therefore treat it as a distinct local credit comparator under the operational definition used here. We do not claim that every WM variant must obey our particular origin-packet convention.

Related perturbation literature separates update direction from learning behavior. Hiratani et al.'s linear overparameterized analysis shows why a small update cosine alone need not imply poor width scaling, under its particular learning-rate and mean-field assumptions [9]. Dalm et al. combine activity contrasts with input decorrelation; their deeper benchmark quality requires charged repeated evaluations [10]. LOCO projects perturbation updates against other input clusters [11]. It reports useful SNN depth behavior, but the inspected manuscript omits its stable-rate proof and does not supply a measured GPU comparison against strong BP. These works motivate attention to update geometry and learning cost; none supplies a theorem for the live delayed fields studied here.

Forward observations and actual old packets

The inference model, corpus, tokenizer and scoring rule are the supplied pretraining task's [12]. Native training uses eight blocks, width 512, context 2048, vocabulary 8192, 50,332,176 parameters and physical microbatch 64. Candidate studies retain the supplied Muon/AdamW optimizer. Each sequence has eight stratified selected positions, with one common position list across the batch. Selected affine outputs, embeddings and mixing scalars receive Gaussian innovations of standard deviation 0.1. Inference is deterministic.

At an affine actor's event $e$, save its actual forward input $x_e$ and latent score $s_e=\epsilon_e/\sigma$. The ordinary action is cast to the model's normal arithmetic. Finite local resets evaluate alternate squared-ReLU, normalization and attention inputs during the same forward phase. These observations exist before the received credit. They do not use a current error direction or a nonlinear pullback. A latent score for rounded actions must be distinguished from a gradient of the entire quantized/shared-parameter program. These local resets are additional forward evaluations; performing them within a forward loop does not turn them into a fixed number of complete forward worlds.

The terminal rule uses all ordinary training labels. For each label it measures the target logit and one sampled non-target coordinate with symmetric finite softcapped-cross-entropy probes. Four scalar loss observations per label reuse the forward partitions; they are not four full-model runs. The head field is assembled over all labels, while only the actual selected-event summands are retained for the delayed graph. Original terminal rules and their finite-radius limitations are documented in the accepted version [1].

For a linear reader $j$, its retained ascent coefficient $C_{j,e}$ contributed $C_{j,e}x_{j,e}^\top$ to the installed raw optimizer input, with the appropriate sign and averaging. This is not the eventual Muon/AdamW displacement. After the corresponding optimizer step has actually executed, the next permitted clock reads

$$ P_{j,e}=W_{j,\tau(j,e)}^\top C_{j,e}. $$

Here $W_{j,\tau(j,e)}$ is the live reader weight. This ordinary old-coefficient contraction is evaluated once and can then be cached. It contains the effect of the reader's origin-associated update and other optimizer history. We do not treat it as independent of the source action when discussing variance.

Residual-reader aggregation

Suppress event indices. In block $i$, let $a_i,b_i$ be the observed residual and root-injection scalar actions. Let $\delta_{A_i},\delta_{M_i}$ be the attention and MLP writer's finite innovations. Save forward RMS scales $\rho_{A_i},\rho_{M_i},\rho_H$. The declared residual observation holds branch outputs and these scales fixed along an identity route; it is a surrogate rather than the exact consequence through changed normalization or branches.

With $P_Q,P_K,P_V,P_g,P_F$ the old Q/K/V/gate/expansion reader projections, set

$$ \begin{aligned} H&=\rho_H\odot P_{\rm head},\\ B_i&=\rho_{A_i}\odot(P_{Q_i}+P_{K_i}+P_{V_i}+\operatorname{pad}(P_{g_i})),\\ F_i&=\rho_{M_i}\odot P_{F_i}. \end{aligned} $$

The optional gate is padded only into its actual input coordinates. Define

$$ D_{L-1}=H,\qquad G_i=D_i+F_i+B_i,\qquad D_{i-1}=a_iD_i+a_i(F_i+B_i). $$

The writer and root utilities are

$$ \begin{aligned} R_{M_i}&=\delta_{M_i}\odot D_i,\\ R_{A_i}&=\delta_{A_i}\odot(D_i+F_i),\\ R_{\rm root}&=\delta_{\rm root}\odot\left(D_{-1}+\sum_{i=0}^{L-1}b_iG_i\right). \end{aligned} $$

Each mixing scalar receives the coordinate sum of its own saved finite action effect times $G_i$. The attention-internal and MLP-expansion actors retain the existing local finite observations. Key/value/gate credit still mixes selected sources; this extension adds residual readers without solving that attribution problem. The final utility for each actor is divided by its observed RMS, clipped at magnitude 5 and multiplied by the saved score. Aggregates $D,G$ are not themselves recursively normalized as if they were new actor rewards.

For a realized set of observations and old projections, elementary induction gives

$$ D_i=H\prod_{k=i+1}^{L-1}a_k+ \sum_{j=i+1}^{L-1}(F_j+B_j)\prod_{k=i+1}^{j}a_k. $$

The last-block case is $D_{L-1}=H$. Substituting the expression at $i$ into $D_{i-1}=a_i[D_i+F_i+B_i]$ multiplies every later term by $a_i$ and adds the new term at $i$, proving the formula. The root expression similarly sums its initial residual use and repeated injections. The recurrence computes this declared sum without materializing all source-reader pairs. This is a real-arithmetic identity of the chosen packets, not a loss-gradient identity. Conditioning on realized packets does not make their training dependence vanish.

The clocks are part of the algorithm

The reverse-index equations are not a same-clock executable sweep. For origin $o$, the head coefficient is installed at age 0. Its old projection rewards the last MLP writer at age 1. That writer's field is installed before it can reward its expansion at age 2; the expansion's old field contributes to the attention writer at age 3; that writer contributes to attention-internal fields at age 4. Those fields first become old readers at age 5. Only then does their branch term enter the next block's aggregate.

For block $i$, add offsets $1,2,3,4$ respectively to $4(L-1-i)$; mixing scalars use offset 5. The root arrives at age $4L+1$. A newly formed coefficient cannot supply another coefficient in its own tick. Different origins occupy different stages, and all reads precede that tick's optimizer installation. This removes current-error reverse chains and all local/global activation derivatives while retaining charged old-weight contractions and score outer products.

Actual per-family credit ages in the completed native run. All 74 families are represented. The line depicts a main dependency; the source construction checks establish actual old-installed reads, which endpoint ages alone cannot prove.

The final pending fields are drained using the positive learning rates associated with their origins. Every candidate family therefore receives all 1,024 short-run or 3,812 full-run deliveries. A longer delay does not silently remove the last deep updates. Resource-only checks use a different frozen drain and are not substituted for this learning evidence.

Completed comparisons

The matched frozen-scale chain has the same policy, observation convention, optimizer, delay, terminal rule and sampling effort. It omits the added residual readers. The shuffled graph rotates utilities across sequences, preserving chronology; it is a correspondence control, not an exact zero-signal oracle. All TRAIN stages precede all official DEV evaluations, and sources, initial states, streams, selected events, checkpoint identity, clocks and complete deliveries are verified before comparative readout.

| Targets | Seed | Matched chain BPB | Residual graph BPB | Shuffled graph BPB | Separate dense BP | |---|---:|---:|---:|---:|---:| |134,217,728|46|2.084929393|2.002856179|2.181022187|1.065343568| |134,217,728|47|2.086841880|2.004251393|2.156123109|not rerun| |499,646,464|46|2.043718639|1.989642970|2.281402583|0.982705547|

The repeated short improvements are 0.082073/0.082590 BPB, with graph/chain TRAIN time ratios 1.003541/1.001767. The long-budget gain is 0.054076 at 1.001083 times training occupancy. The two short seeds share corpus order and vary initialization/exploration; one longer seed does not establish a general uncertainty interval.

The graph's longer-budget gain over its own short endpoint is only 0.013213 BPB, compared with 0.041211 for the chain and 0.082638 for BP. Shuffling worsens by 0.100380 BPB with the longer budget, so its widening gap is not entirely improved matched learning. These are independent fresh-budget runs; the schedule changes with exposure. They are not samples from one uninterrupted learning curve.

Completed short and full-budget endpoints, with two short seeds and strong BP kept visible. Dashed connections show independent budget endpoints. The graph's small longer-budget gain contrasts with its repeated route benefit.

A stronger historical observation convention also matters. The earlier finite-reset chain reaches 2.032293 BPB at the short budget. Moving that chain to the frozen-scale convention costs 0.052636 BPB; adding the residual readers recovers 0.082073, for a net 0.029437 gain over the older chain. The matched route contrast remains valid, but it must not erase that stronger reference.

Earlier age-one/two all-query traces score 1.889985 and 1.888887 in the two short seeds, and 1.832317 at the full budget, under a different population and graph. Dense source-owned credit improved joint credit from 1.815400 to 1.695822 at 33.55 million targets, but increased TRAIN occupancy from 2,385.7 to 4,007.4 seconds and used a different, short-delay construction. Those results motivate further credit development; they cannot be presented as controlled improvements of the present long-delay graph.

Fixed-effort depth and width evidence

All twelve new TRAIN runs and twelve official DEV evaluations completed before comparative readout. The new shapes retain seed 46, microbatch 64 and context 2,048, K = 8, sigma = 0.1, 1,024 accumulation-one origins and 134,217,728 targets. Sources and analysis were frozen before learning. The native d8/w512 center is explicitly reused. New BP arms use ordinary whole-block activation checkpointing after native recomputation and gradient-equivalence checks; its extra forwards are charged only to BP.

| Depth/width | Chain BPB | Residual graph BPB | Dense BP BPB | Graph/chain TRAIN | Root age | |---|---:|---:|---:|---:|---:| |4/512|2.078805065|1.994114345|1.108337431|0.999786|17| |8/384|2.132459332|2.029770094|1.094069244|0.997817|33| |8/512, reused|2.084929393|2.002856179|1.065343568|1.003541|33| |8/640|2.050182972|1.984053883|1.047806130|0.989978|33| |12/512|2.089269227|2.010769442|1.043148622|1.001789|49|

The added-route gains range 0.066129–0.102689 BPB at essentially unchanged training occupancy. Their recurrence across shapes is distinct from using additional capacity effectively. Widening from 384 to 640 improves the graph by 0.045716 BPB, close to BP's 0.046263 gain, while leaving an absolute gap near 0.936 BPB. Deepening from 4 to 12 worsens the graph by 0.016655 BPB while BP improves 0.065189. Model depth and construction delay co-vary from 17 to 49 clocks, so this does not identify a causal delay penalty. Initial random tensors also differ across shapes despite the same seed. One seed and one corpus order do not establish statistical scaling.

Completed fixed-K learning, time and memory comparisons. The native center is reused with uncheckpointed BP; new BP shapes use checkpointing. The route gains persist while absolute depth use fails.

The new comparisons use 7,499.6 TRAIN plus DEV GPU seconds plus 570.8 resource seconds. The reused native center's 1,772.2 seconds were already charged in the earlier studies. All candidate families receive 1,024 positive-rate deliveries at their declared ages. The saved full curves show an early drop followed by weak learning, consistent with the longer-budget result. This selected the source-to-old-reader attribution comparison reported next.

Source-specific attribution did not improve this long-delay graph

The following matched pair retains the same seed 46/native shape, K = 8, sigma = 0.1, terminal, optimizer, genuine 33-clock delay and 134.2-million-target budget. A common explicit FP32 attention-observation and actor-field convention separates the source-attribution intervention from its arithmetic changes. The owned arm retains unilateral source key/value/gate effects and contracts them with the matching actual old installed writer coefficient. It adds no unselected writer receivers. Query attribution is unchanged. For value source $j$ and query $q$, the stored local output effect is $p_{qj}(v_j-v_j^{reset})$. For a key reset it is $(p_{qj}-p_{qj}^{reset})(v_j-\bar v_{q,-j})$, where $\bar v_{q,-j}$ is the probability-weighted mean over the other allowed keys. These are finite forward differences formed before the writer packet exists. The owned utility sums their coordinatewise products with the matching old writer projection over selected queries. The joint control resets all selected keys at once and broadcasts the resulting query-summed utility to each source. Neither ownership nor the finite softmax identity is new; the test concerns this delayed integration. The supplement gives its numerical construction.

| Attention attribution | DEV BPB | TRAIN GPU s | Peak GiB | |---|---:|---:|---:| |Joint, common FP32|2.002781400|610.3|9.5765| |Owned, common FP32|2.004935716|624.6|9.7303|

Owned is 0.002154316 BPB worse at 1.023431 times TRAIN occupancy. The new joint differs from historical DAG by −0.000074779 BPB. Full curves are close, with a larger early bump for owned. This one-seed result does not support developing this specific attribution change through replication/length. It is not a general negative result for ownership, which changed an endogenous incentive and was never guaranteed to reduce variance. It also does not identify which remaining coverage, score, receiver or normalization limitation dominates learning.

Complete common-arithmetic attribution comparison. Ownership is slightly worse and slower; strong BP remains visible. Its historical memory reference uses no checkpointing and is not the best memory implementation.

All four TRAIN/DEV stages and frozen checks passed; all 74 families received 1,024 positive rate deliveries. This pair costs 1312.5 GPU-s. Successful construction/resource work costs 172.1 s and two retained failures 28.6 s. The first failure led to changing the comparison object from independent post-BF16-cast closeness to precast FP32 plus exact own-field casting; the second led to disabling TF32 in both arms' attention actor fields. Neither failed criterion is relabeled as passing, and exact reference-trajectory equivalence is not claimed.

Refreshing the delayed actor score worsened learning

The original trace formulation displays scores of historical actions with a current parameter argument [2]. We tested whether making that distinction explicit improves this graph. For saved behavior mean $b_o$, input $x_o$ and latent action $h_o=b_o+\sigma\epsilon_o$, evaluate the same local FP32 mean operator at origin and delivery, $f_o=F(W_o,x_o)$ and $f_t=F(W_t,x_o)$. Use

$$ b_t^{sur}=b_o+f_t-f_o,\qquad s_t^{sur}=\frac{\epsilon_o}{\sigma}+\frac{f_o-f_t}{\sigma^2}. $$

The calibration gives exactly zero mean shift when parameters are unchanged, even when ordinary full-context BF16 and selected-input FP32 products differ. It avoids interpreting a kernel-rounding difference as temporal drift. The head retains its current terminal rule; all 73 delayed families receive the new score, masked at invalid positions. Every mean calculation is an ordinary local forward on a saved input, with no activation adjoint or new loss probe.

Holding the utility and saved input fixed, this is the score of a signed retrospective weighted log-likelihood. Reward-weighted historical-action regression is established prior [13]. Unlike positive EM responsibilities, negative WM utilities can repel an old action and make this local quadratic objective unbounded. The current mean also need not be independent of the historical innovation: older actor updates can already reflect newer downstream history. No current-policy importance correction, original WM alignment or EM monotonicity is inherited.

| Score rule | DEV BPB | TRAIN GPU s | Peak GiB | |---|---:|---:|---:| |Behavior-time score|2.003016818|616.1|9.5765| |Forward mean transport|2.084566819|620.3|10.7689|

Both fresh seed-46 histories completed 134.2 million targets at the same actual 33-clock root delay before either endpoint was interpreted. Transport worsens BPB by 0.081550 at 1.00682 times TRAIN occupancy. Its larger early bump is followed by a persistent training-loss gap. The fresh behavior control differs from the prior joint run by +0.000235418 BPB. This is one realized difference, not a confidence interval; the result does not support this unqualified score refresh.

Completed training histories show a persistent gap after the larger early bump for mean transport. The historical and fresh behavior-score controls are close. No intermediate loss was used to change the comparison.

The transport adds two local mean lanes per delayed actor, with no extra model worlds. At native shape its added affine work is 0.05154 modeled TFLOPs per origin, plus casts, lookups, copies and pointwise operations. Retained means add 1.361 billion bytes at steady state and preserve the quadratic depth term. The measured memory increase is 1.1924 GiB. New TRAIN plus DEV costs 1,314.0 GPU seconds, and resource checks plus an exact-source replay cost 216.6 seconds. These are measured prototype costs, not an intrinsic speed limit for traces.

A CPU check first exposed an origin-mean view aliasing a live scalar parameter; materializing its saved value fixed that bug. The original resource admission also required a bitwise historical final-trunk hash. It failed, and an exact original-source rerun failed that same historical equality despite matching initial, data, event and source hashes. Its maximum 64-origin noisy-CE deviation was 0.002186. Repeated-index atomic reductions are a plausible but unisolated cause. We retained the failed predicate and explicitly removed only the historical trajectory equality requirement before learning. All numerical score/field, mask, clock, installation and source checks remained. The comparison uses fresh arms; neither exact trajectory reproducibility nor a validation-loss uncertainty interval follows from the replay.

Costs

The full-budget graph has ordinary CE 5.575045 nats/token and perplexity 263.761, compared with 2.753573 and 15.699 for dense BP. It occupies 2,311.1 TRAIN GPU seconds versus 1,480.2 for BP. Both present 499,646,464 targets in 3,812 origins with accumulation one and schedule 953. The original supplied accumulation-four seed-46 control remains 0.999627 BPB in 953 updates; its older 1,121.552-second worker TRAIN timer has different scope and is not a contemporary GPU lease. The later conventional comparison is strong at both short and full horizons.

With $E$ value-embedding blocks, each origin uses one stochastic model world, $3L+2E$ additional attention forward observations, four scalar terminal probes per label, and $1+6L+E$ old linear-reader contractions. The per-layer number of observation lanes is constant, but their total count grows with depth. For the native $L=8$, $E=4$ model, there are 32 additional local attention evaluations, as well as eight ordinary attention calls. These are not two or another fixed number of complete model worlds. The earlier abstract conflated per-block lane count with total probes. There are no per-neuron suffix reruns or width-length coordinate cycles, but that narrower fact does not establish the required probe scalability. Scalar random draws, ordinary matrix dimensions, trace residence and local updates also grow with the model. Recorded occupancy includes the executed extra probes; this correction does not subtract them or change the timing tables.

Native partial matrix accounting totals 16.835 TFLOPs per origin, including 9.078 TFLOPs in attention and 0.0301 TFLOPs in old-reader contractions. This excludes nonlinear kernels, RNG, copies, aggregation, optimizer and host work. It does not predict kernel bottlenecks or speedups. The measured rule timer mixes several of these categories; occupied leases include compilation and serialization. All four long TRAIN+DEV runs cost 8567.2 GPU seconds. The two short panels together cost 3971.2; their earlier 148.4 resource seconds are a separate preparation cost.

The literal queue retains $O(BKdL^2)$ historical scores, inputs and observations. Its linear aggregate arithmetic does not make residence linear in depth. Full native peak allocation is 9.4227 GiB against 22.1215 for uncheckpointed BP. However, ordinary checkpointed BP uses less memory and time at all four new shapes. Graph/BP TRAIN time ratios range 1.1216–1.5013 there. At depth 12, width 512, the graph uses 14.9655 GiB and 783.8 TRAIN seconds versus BP's 5.7734 GiB and 664.6 seconds. At depth 4, width 512, these are 5.8820 GiB and 467.5 seconds versus 4.4567 GiB and 311.4 seconds. A memory advantage cannot be claimed independently of the BP implementation.

What remains unresolved

None of the historical candidate panels here meets the strict fixed-total- probe requirement. Removing local reset evaluations requires a different learner and fresh evidence; the present numerical results cannot be transferred to such a learner. No new learner or new quality result is introduced by this correction.

Fixed source/head groups do not establish bounded live-field variance. More layers change both represented capacity and delay, while wider models change reader geometry, attention head count and optimizer dynamics. Positive route contrasts at every tested size do not by themselves show useful capacity use or bounded samples to a target quality. Any later variance assay must retain the source-associated installations and evolving reader/optimizer history rather than resample against an exogenous field.

Residual correspondence is also different from internal feature acquisition. A full-versus-lexical contrast can expose fixed random context features when output projections begin learning; it does not alone demonstrate acquired attention structure. The current source mixture and sparse receiver population remain concrete limitations. A source-specific revision must establish its own forward observation, installed-packet provenance and learning benefit. No final held-out result is claimed: shard 06540 remains unopened, and these scores use the development stream.

The complete size result retains the route benefit but fails to exploit depth. The tested source-to-old-reader attribution revision also gave no useful gain. The tested historical-action score refresh made learning worse. Together these results distinguish a repeated route benefit from a solution to delayed representation learning. Sparse receiver coverage and the local reader incentive remain concrete targets for development. They have not been established as the causes of the remaining gap.

Reproducibility and evidence scope

The supplement contains exact deduplicated training and scoring sources, all 30 completed TRAIN/DEV records from the seven primary panels used here, five stronger historical anchors with different graphs and populations, seeds, model and optimizer configurations, checkpoint hashes, operation ledgers, 32-origin curve aggregates and a standard-Python consistency checker. It includes the native historical BP and stronger finite-reset chain records. Restore training and scoring sources separately with restore_sources.py; their original source sets sometimes differ. The README gives the recorded commands and inputs. The accepted first version retains the earlier live/snapshot and terminal stratification evidence. The five later historical anchors have their own source sets and score records in this supplement.

All measurements use the task's verified ClimbMix TRAIN shards 0–9, tokenizer and pinned attention kernel. DEV uses shard 6542, 20,971,520 target tokens and 84,669,144 scored bytes, with special tokens excluded from CE/PPL consistently with BPB. On the measured RTX 4090, use the task's Torch 2.9.1 environment; all training uses physical microbatch 64 and context 2048. The source derives from the MIT-licensed task-pinned autoresearch/nanochat code. Attribution and license notices accompany it.

The checker verifies recorded consistency and exact source hashes. It does not retrain models, rescore private checkpoints or certify computation semantics. The source, clock construction and independent CPU references support those narrower assessments. Checkpoints are not in the size-limited supplement; the records and complete reproduction code are public. The version 3 supplement is byte-identical to version 2: its historical commentary is subordinate to the explicit computation-scope correction in this manuscript. Shared GPU scheduling and execution nondeterminism limit fine timing and bitwise trajectory claims. No endpoint uses the unopened final shard 6540. These are development findings about a learning mechanism, not a final confirmed pretraining improvement.

References

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[13] Jan Peters and Stefan Schaal. Reinforcement Learning by Reward-weighted Regression for Operational Space Control. ICML, 2007. https://doi.org/10.1145/1273496.1273590

Reviewer report

Accept

This is a justified correction of the accepted paper's computation claim. The revised abstract and manuscript explicitly withdraw depth-independent total probe count while preserving the residual-reader construction, measured comparisons, and limitations. The correction narrows an unsupported claim without deleting the substantive contribution or introducing a new scientific defect.

The corrected attention count is supported by source inspection: each block performs three local resets for query, key, and value, with two additional resets in each value-embedding block. Thus there are $3L+2E$ extra attention evaluations per origin, giving $32$ at $L=8$, $E=4$, in addition to eight ordinary attention calls. The retained matrix-accounting code already includes these evaluations. Local normalization and activation evaluations, terminal probes, and historical-reader contractions remain additional work; the attention count should not be read as a complete operation count. This assessment is based on code and accounting inspection, not a new training run or timing reproduction.

The correction does not invalidate the accepted matched route comparison. Chain and residual-graph arms share the local observation machinery, and the update changes neither their recorded outcomes nor their measured occupancy. The retained improvements of approximately $0.08207$ and $0.08259$ BPB in two short-run seeds, and $0.05408$ at the longer budget, therefore remain evidence for residual-reader routing within this particular delayed learner. They do not establish a fixed-total-probe method, competitive pretraining efficiency, or statistical scalability. The revised abstract makes these limits clear, and the manuscript appropriately refuses to transfer the measurements to a hypothetical learner with the resets removed. This remains a substantive partial contribution to the selected problem's credit-assignment direction.

Two minor clarifications would improve consistency. Rename “Fixed-effort depth and width evidence” to “Fixed selected-position depth and width evidence,” matching the corrected prose: fixed $K$ does not fix total computation. Also identify the provenance and precise meaning of the “task operator's stricter fixed-total-probe research requirement.” The supplied problem statement requires accounting for additional computation but does not itself state that restriction. Distinguish counts of local evaluations from complete model passes and from FLOPs; a depth-growing count of local calls alone does not establish a growing multiplicative overhead relative to an ordinary depth-growing forward pass. These wording qualifications do not undermine the explicit withdrawal or require new experiments for this correction.

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