Topological reuse · research in progress

Networks that solve similar problems build similar shapes. One network can read those shapes and reuse its own circuits.

One idea, tested in numbered notebooks: networks that solve structurally similar problems build similar circuit shapes (rings and waves on clock arithmetic), so one network can read those shapes from a short probe and reuse its own circuits through small lenses, learning faster, smaller and from less data.

Arthur Boscoli Rodrigues · findings as of 2026-10-05 · page built 2026-10-05
A living page. A chapter is added when its experiment has run on fresh seeds and its figure is ready; the table at the end is rebuilt from the project's findings every time. The chapter texts are a first draft.

1 · The shape

A ring says “clock”. Its arrangement says which clock.

A small network learned to add on a 31-hour clock. What it built is nine rings, each with the thirty-one numbers around it, each counting its way around at a different rate. The network found this on its own; it was never shown a clock.

The rings can be found without being told where to look: groups of neurons that read the same directions give them away (notebook 3). And they can be put to other use: a lens of 64 to 80 trained numbers turns the frozen rings of addition into subtraction, and taking the lens off restores addition (notebook 5).

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Interactive figure

The Clock Inside the Network

  • A ring says “clock”.
  • Its arrangement says which clock.
  • A lens is a turn or a mirror.
  • How it forms.
Open it in its own tab

Sources in the project: findings/nb01_ring_detection.json, findings/nb03_general_matcher.json, findings/nb05_sharing_lenses.json, figures/data/fig01_rings.json

2 · The payoff

What reuse buys

A lens is a small trained map placed in front of a frozen circuit so that it serves a new task. The frozen circuit already holds the clock; the lens only has to turn it. The figure walks through what that buys, in steps and in examples.

Open this figure on its own

Sources in the project: figures/data/fig03_curves.json, findings/conventions.json

3 · The loop

What the reader sees, what deciding costs, what an adapter weighs

Before it can reuse a circuit, the network has to decide which one. It trains a short probe on the new task and reads the probe's shape: deciding by shape from a 500-step probe of the output end is accurate, cheap and robust to unseen formulas (notebooks 7, 8 and 11).

Run as one loop over a stream of 15 tasks, a single network makes 12 of 13 right calls in every seed and ends at 59–64% of the size of separate networks, with 24–36% of the steps (notebook 8).

Interactive figure

The reader, the stream, the costs, the adapters

  • The Reader’s View
  • Fifteen Tasks, One Network
  • What Deciding Costs
  • What an Adapter Weighs
Open it in its own tab

Sources in the project: findings/nb07_learning_to_read.json, findings/nb08_whole_loop.json, findings/nb09_adapters.json, findings/nb11_deciding.json, figures/data/fig02-05_data.json

The record

Where the evidence stands

Every notebook fixes its rules before its fresh seeds run; a rule passes if it holds in at least 4 of 5 seeds. This table is rebuilt from the project's findings each time the page is built.

No.NotebookWhat it foundResult
1ring detection weekend testrings exist and are clean with the answer key (10/10, no false alarms); blind whole-layer views failpassed, with the answer key
2grafting oracle testa perfectly placed 128-weight bridge helps B learn (less data, 1.4-1.9x faster); copying the whole table helps morepassed
3general matcher testneuron groups find the rings without the answer key (1.11-1.15 vs controls 0.11-0.29); end to end B beats no help 5/5passed
4fewer neurons testa bridge teaches, it does not share: B copies the rings; size savings not consistent at 30,000 stepsmixed
5sharing testa lens of 64-80 trained numbers turns add's frozen rings into subtraction 5/5; lens off restores add; mul unreachablesharing passed; fewer neurons did not hold
6one network many tasksone network decides by ring matching, ends at 64-72% of separate networks, 42-79% of the steps, learns reused tasks from 96 pairspassed (7/7)
7learning to read circuitsread the output end (95-96% vs 73-77%); a learned reader works on unseen families from 500-step probes; the features do the workpassed (8/9; the miss is a setup check)
8whole loop one networkthe whole loop in one network over 15 tasks: 12/13 right calls every seed, 59-64% of the size, 24-36% of the steps, output lens reaches the square-at-the-end decoyspassed (10/10)
9adapters which lensthe ring lens is the smallest adapter that does the turn tasks and needs real rings; table tune retires the full lens; freezing matters at 96 pairspassed (4/4 rules, 10/10 seeds)
10one shared networka one-table shared network cannot learn the mixed stream at any setting; per-task tables fix it; the fair baseline ran as notebook 10binconclusive; cause diagnosed
10bnb10b fair shared networkagainst a shared network with a table per task, the loop learns a new task in 200-250 steps vs 400-550 (5/5) and from 96 pairs scores 71-87% vs 38-51% (bar met 3/5); the shared network never learns four chain-like tasksmixed (steps 5/5; data 3/5, short of the 25-point bar)
11deciding by shapethe reader decides as well as trying at a fixed 500-step cost, wastes a fifth of guessing, handles unseen formulas; |a-b| and floor((a+b)/2) are its blind spotpassed (5/5)
13nb13 chainsstored links compose: all 171 readable chains answer composite tasks such as (a - b)^2 at 94% or better with no training; the right chain is the top scorer among 55 on 80 check pairs every time; chains reach 45 of 45 cube composites where learning reaches 20passed (4/4 rules, 5/5 seeds)
14nb14 addressespieces can be found by what they do: a piece learned again lands at the same address (237 of 237), a chain's address follows from its pieces' (1,397 of 1,399), and a search one piece at a time finds the chain with one run instead of 336 (1,526 of 1,528) or says exactly what is missing (1,300 of 1,300; 420 of 420); but a stored output link does not move to the other circuit (1 of 130) and two rarely stack (117 of 836)passed (5/5 rules, 5/5 seeds)
15nb15 common codewhy stored links did not move or stack, and the remedy: a link on raw scores reads its circuit's own pattern (shuffle the 30 losing scores: 1 of 127 links survives); a link that reads the softmax of the scores learns every step (130 of 130, raw 127), works behind the other circuit and another network (130 of 130 each, raw 1 and 3 of 127), and stacks (1,690 of 1,690 pairs; every sequence of six, raw 0%)passed (5/5 rules, 5/5 seeds)
16nb16 library around a transformerthe library carries over when the frozen circuit is a one-layer transformer: output links 130 of 130, input links found by counting 110 of 110, chains 1,430 of 1,430, pairs 1,690 of 1,690, the search 1,560 of 1,560, and pieces move between a plain block and a transformer both ways; the one piece that reaches inside, a table tune learned through the transformer, does not (29 of 110, against 110 of 110 through a plain block)passed (5/5 rules, 5/5 seeds)
17nb17 inside the transformerthe inside of a one-layer transformer is built like a block's: the ring detector finds rings in all 10 trained circuits and none untrained, they are the predicted waves, and a lens that only turns or mirrors those waves (24-32 trained numbers) reuses the frozen circuit: with 96 pairs it averages 95% where the same lens on random planes gets 8% and a free table tune 38%; it never fits a task outside its reach; all 30 links within reach reach 90%passed (rules 1-5 in 5/5, 4/5, 5/5, 5/5, 5/5 seeds; reach 30 of 30 links)

passedmixedinconclusive or open

What stands

  • Shape carries reuse: the ring lens works only on real rings (nb 5, 9).
  • Reuse goes through lenses on frozen circuits; freezing is what makes 96-pair learning possible (nb 5, 9).
  • Deciding by shape from a 500-step probe of the output end is accurate, cheap and robust to unseen formulas (nb 7, 8, 11).
  • One network runs the loop with the three savings: space, steps, data (nb 6, 8).
  • Against a fair shared network, a frozen circuit with a table tune still learns a new task in fewer steps (5/5 seeds) and is ahead with 96 pairs in every seed, by 23-42 points, short of the 25-point bar in two (nb 10b).
  • Links are separable pieces: an input link and an output link learned on different tasks compose around a frozen circuit into tasks neither was trained on, and the right chain is found by trying the library on 80 pairs, without names (nb 13).
  • Pieces can be found by what they do: an address computed from behaviour puts a piece learned again, and its twin of another kind, at the same place; the address of a chain follows from its pieces' addresses; and a search that looks for one piece at a time finds the chain with one run instead of 336, or says exactly what the library is missing (nb 14).
  • Pieces move and stack when they talk through a common code: a link that reads the softmax of a circuit's scores, instead of the raw scores, works behind any circuit and any network and stacks six deep without training; a link on raw scores reads its own circuit's pattern and does neither (nb 15).
  • The library does not care what kind of network the circuit is: with a one-layer transformer as the circuit, common-code output links, input links found by counting from the circuit's stored answers, chains, stacks and the search all work, and pieces move between a plain block and a transformer; every such piece stays outside the circuit and names symbols (nb 16).
  • Shape carries reuse inside a transformer too: in one-layer transformers trained on the clock tasks the ring detector finds rings from the weights alone (none before training), they are the waves arithmetic predicts, and a lens bound to them reuses the frozen circuit from a fifth of the data, where random planes do nothing and a free table tune needs all the data (nb 17).