The Thue–Morse word is one of the most-studied objects in combinatorics on words, because its self-similarity keeps turning into clean patterns. Here is a recent one.
The Campbell–Currie–Rampersad conjecture studied here concerns the reduced abelian complexity R(n) of the Thue–Morse word. For every factor of length n, first run-compress it, replacing each maximal run of equal letters by a single letter; then record its Parikh vector, the pair counting how many 0s and 1s remain. R(n) is the number of distinct such vectors. This statistic blends local run structure with the celebrated self-similarity of Thue–Morse, making a clean recurrence especially striking.
The Thue–Morse word contains scaled-down copies of its own structure. That self-similarity leaves a precise echo in this count: at odd length 2n+1, the complexity is exactly the value at length n+1. It is as if the counting problem folds in half while retaining the same answer. We proved this fold.
For every n, we prove R(2n+1) = R(n+1). As an immediate consequence, R(2^k+1) = 3 for every k ≥ 0. The theorem establishes the odd-length recurrence; even-length behavior and the non-automaticity question remain outside this result.
The result was verified by Lean at the kernel level, with no sorry, including a proof that the Lean statement faithfully corresponds to the original proposition. Result page: https://t.co/Pb5JWF1wSX
#Lean4 #AI4Math #FormalMath #Combinatorics #OEIS
We have brought our formalization work to date into an interactive publishing site: a mathematical Atlas. Lean remains the single source of truth carried through our upstream and downstream engineering, while the site turns that verified body of work into something people can browse and trace. We want to see how clusters of logic take shape and where concepts meet inside formalized mathematics. We also want to understand which edges exert more influence than others.
The Atlas currently offers several ways into the same body of work. Its category-organized DAG lets you click into any concept and trace its upstream and downstream connections to the relevant concept wiki and visual map of related ideas. The Dependencies view looks across fields for constants and parameters that keep recurring, with the aim of finding the most stable, least shifting anchors. We find this especially interesting because minimization and metalanguage keep returning to a similar search: the core within the core, the most fundamental structures that move the least. The Open Problems view draws bridges between the questions we are tackling and the concepts that have already been formalized, making it possible to see where current work attaches to the Atlas and what foundations it draws on.
Looking ahead, we want to explore whether this DAG can be optimized in a way that resembles the optimization of protein structures or an energy landscape, so that the structure latent in mathematical logic can reveal itself and evolve through the process. Each release is one step in that evolution. The Evolution page will make the path visible, including the paths AI chooses as it explores how the Atlas might develop.
The Research page gathers our latest results, drawn from an open-problem and conjecture library that we curate ourselves. We will keep connecting open questions to this library and working through them. Over time, we hope this will lay stronger foundations for the next stage of formal AI for mathematics. We are also glad to share that we have already solved some of these conjectures. The next few posts will go deeper into what we found.
Atlas: https://t.co/DedN5c7isU
Some sequences are defined by a rule you keep applying forever, one step at a time, and the open question is whether all that stepwise work has a simple description. Here is a case where it does.
Bosma et al. Conjecture 17, from JIS 28 (2025), 25.3.8, concerns a two-parameter family of greedy 3-sumfree sequences. Starting from seeds determined by (g,d), the construction repeatedly admits the smallest integer that cannot be written as the sum of three distinct terms already admitted. This is an infinite process governed by a local test at every step, yet the conjecture predicts a global periodic description of all its members. Establishing that bridge makes membership decidable directly from a formula.
Think of building a numbered roster one entry at a time. At each step, you add the smallest available number that cannot join three distinct numbers already on the roster to make the forbidden equation “their sum equals this new number.” A direct construction seems to require checking the roster forever. The conjecture says the completed roster actually falls into periodic windows, so a single formula tells you who appears. We proved that the step-by-step rule and the formula produce exactly the same roster.
For 2 ≤ d and d+1 ≤ g, we prove the exact membership criterion: z is a term ⟺ z ∈ {1, g, 2g+d−1, 2g+d} or z lies in the conjecture's periodic window modulo 5g+2d. We also prove that this closed form agrees with the literal greedy rule at every step. For (g,d) = (3,2), the sequence begins 1, 3, 5, 6, 7, 8, 22, 23, 24, 25, 41, 42, 43, 44, 60; for (g,d) = (5,3), it begins 1, 5, 8, 9, 10, 11, 12, 13, 37, …. The theorem applies when 2 ≤ d and d+1 ≤ g; the separate seed family involving g+1 lies outside its scope.
The result was verified by Lean at the kernel level, with no sorry, including a proof that the Lean statement faithfully corresponds to the original proposition. Result page: https://t.co/CdZNC8HKqf
#Lean4 #AI4Math #FormalMath #Combinatorics #OEIS
We have brought our formalization work to date into an interactive publishing site: a mathematical Atlas. Lean remains the single source of truth carried through our upstream and downstream engineering, while the site turns that verified body of work into something people can browse and trace. We want to see how clusters of logic take shape and where concepts meet inside formalized mathematics. We also want to understand which edges exert more influence than others.
The Atlas currently offers several ways into the same body of work. Its category-organized DAG lets you click into any concept and trace its upstream and downstream connections to the relevant concept wiki and visual map of related ideas. The Dependencies view looks across fields for constants and parameters that keep recurring, with the aim of finding the most stable, least shifting anchors. We find this especially interesting because minimization and metalanguage keep returning to a similar search: the core within the core, the most fundamental structures that move the least. The Open Problems view draws bridges between the questions we are tackling and the concepts that have already been formalized, making it possible to see where current work attaches to the Atlas and what foundations it draws on.
Looking ahead, we want to explore whether this DAG can be optimized in a way that resembles the optimization of protein structures or an energy landscape, so that the structure latent in mathematical logic can reveal itself and evolve through the process. Each release is one step in that evolution. The Evolution page will make the path visible, including the paths AI chooses as it explores how the Atlas might develop.
The Research page gathers our latest results, drawn from an open-problem and conjecture library that we curate ourselves. We will keep connecting open questions to this library and working through them. Over time, we hope this will lay stronger foundations for the next stage of formal AI for mathematics. We are also glad to share that we have already solved some of these conjectures. The next few posts will go deeper into what we found.
Atlas: https://t.co/DedN5c7isU
A lot of open problems in combinatorics are about simple-looking sequences that quietly hide real structure. Here is one we recently settled.
Chamberland–Dilcher Conjecture 2.1 concerns the sequence d(n,l) = ⌊√(2ln)⌋ − ⌊√((2l−1)n)⌋. Each term compares two interlaced square-root staircases after their fractional parts have been discarded. As l varies, d(n,l) sometimes becomes 0 for several consecutive positions. Those zero blocks encode exact coincidences between the staircases, and the conjecture predicts a surprisingly orderly way to locate and separate them.
Imagine climbing a staircase whose level at each point is set by a floored square root. The level usually rises as you move, then occasionally sticks and creates a short flat stretch; those flat stretches are the consecutive zeros. The conjecture says every eligible label points to one such platform, and platforms carrying different labels never overlap. We proved that picture for odd n.
Precisely, for every odd n and every eligible label λ in the conjecture, the corresponding positions form a consecutive block of zeros in the d sequence, and the zero blocks attached to distinct labels are pairwise disjoint. For n = 21, the relevant values are [2, 2, 1, 0, 1, 0, 1, 1, 1, 1]. For n = 33, they are [3, 2, 2, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 1, 1]. The theorem covers odd n.
The result was verified by Lean at the kernel level, with no sorry, including a proof that the Lean statement faithfully corresponds to the original proposition. Result page: https://t.co/RI47CKDXxf
#Lean4 #AI4Math #FormalMath #Combinatorics #OEIS
We have brought our formalization work to date into an interactive publishing site: a mathematical Atlas. Lean remains the single source of truth carried through our upstream and downstream engineering, while the site turns that verified body of work into something people can browse and trace. We want to see how clusters of logic take shape and where concepts meet inside formalized mathematics. We also want to understand which edges exert more influence than others.
The Atlas currently offers several ways into the same body of work. Its category-organized DAG lets you click into any concept and trace its upstream and downstream connections to the relevant concept wiki and visual map of related ideas. The Dependencies view looks across fields for constants and parameters that keep recurring, with the aim of finding the most stable, least shifting anchors. We find this especially interesting because minimization and metalanguage keep returning to a similar search: the core within the core, the most fundamental structures that move the least. The Open Problems view draws bridges between the questions we are tackling and the concepts that have already been formalized, making it possible to see where current work attaches to the Atlas and what foundations it draws on.
Looking ahead, we want to explore whether this DAG can be optimized in a way that resembles the optimization of protein structures or an energy landscape, so that the structure latent in mathematical logic can reveal itself and evolve through the process. Each release is one step in that evolution. The Evolution page will make the path visible, including the paths AI chooses as it explores how the Atlas might develop.
The Research page gathers our latest results, drawn from an open-problem and conjecture library that we curate ourselves. We will keep connecting open questions to this library and working through them. Over time, we hope this will lay stronger foundations for the next stage of formal AI for mathematics. We are also glad to share that we have already solved some of these conjectures. The next few posts will go deeper into what we found.
Atlas: https://t.co/DedN5c7isU
There's a lot happening in AI for math right now, and it's genuinely exciting to see more people doing remarkable work in the field. We'd like to share a few of our own recent results. The first concerns Pochhammer Conjecture 6.5. Its operator Lₐ is built in the falling-factorial, or Pochhammer, basis, the discrete analogue of the usual monomial basis. The parameter c₂(a) is the left endpoint of the range in which the polynomial's complex zeros are forced onto the real axis while their real parts stay in [−1,0]. The conjecture proposed the strict bound c₂(a) < 2a, so it was asking for a uniform geometric constraint on where those zeros can go.
Think of a as an adjustable dial and 2a as a line that c₂(a) was expected to stay strictly below at every setting. We located the exact transition: the guarantee holds only after the dial passes 1/24. At 1/24 the quantity touches the line exactly, and at every setting a ≤ 1/24 it reaches or crosses the claimed bound.
For quadratic polynomials, the closed-form analysis gives the sharp equivalence c₂(a) < 2a ⟺ a > 1/24. At a = 1/24, c₂(a) = 1/12 = 2·(1/24); for a ≤ 1/24, c₂(a) ≥ 2a. Thus the proposed strict upper bound fails for small a, with 1/24 as the exact threshold. This result settles the quadratic case and leaves higher degrees open.
The result was verified by Lean at the kernel level, with no sorry, including a proof that the Lean statement faithfully corresponds to the original proposition. Result page: https://t.co/dRvdoGC4WY
We have brought our formalization work to date into an interactive publishing site: a mathematical Atlas. Lean remains the single source of truth carried through our upstream and downstream engineering, while the site turns that verified body of work into something people can browse and trace. We want to see how clusters of logic take shape and where concepts meet inside formalized mathematics. We also want to understand which edges exert more influence than others.
The Atlas currently offers several ways into the same body of work. Its category-organized DAG lets you click into any concept and trace its upstream and downstream connections to the relevant concept wiki and visual map of related ideas. The Dependencies view looks across fields for constants and parameters that keep recurring, with the aim of finding the most stable, least shifting anchors. We find this especially interesting because minimization and metalanguage keep returning to a similar search: the core within the core, the most fundamental structures that move the least. The Open Problems view draws bridges between the questions we are tackling and the concepts that have already been formalized, making it possible to see where current work attaches to the Atlas and what foundations it draws on.
Looking ahead, we want to explore whether this DAG can be optimized in a way that resembles the optimization of protein structures or an energy landscape, so that the structure latent in mathematical logic can reveal itself and evolve through the process. Each release is one step in that evolution. The Evolution page will make the path visible, including the paths AI chooses as it explores how the Atlas might develop.
The Research page gathers our latest results, drawn from an open-problem and conjecture library that we curate ourselves. We will keep connecting open questions to this library and working through them. Over time, we hope this will lay stronger foundations for the next stage of formal AI for mathematics. We are also glad to share that we have already solved some of these conjectures. The next few posts will go deeper into what we found.
Atlas: https://t.co/DedN5c7isU
We have brought our formalization work to date into an interactive publishing site: a mathematical Atlas. Lean remains the single source of truth carried through our upstream and downstream engineering, while the site turns that verified body of work into something people can browse and trace. We want to see how clusters of logic take shape and where concepts meet inside formalized mathematics. We also want to understand which edges exert more influence than others.
The Atlas currently offers several ways into the same body of work. Its category-organized DAG lets you click into any concept and trace its upstream and downstream connections to the relevant concept wiki and visual map of related ideas. The Dependencies view looks across fields for constants and parameters that keep recurring, with the aim of finding the most stable, least shifting anchors. We find this especially interesting because minimization and metalanguage keep returning to a similar search: the core within the core, the most fundamental structures that move the least. The Open Problems view draws bridges between the questions we are tackling and the concepts that have already been formalized, making it possible to see where current work attaches to the Atlas and what foundations it draws on.
Looking ahead, we want to explore whether this DAG can be optimized in a way that resembles the optimization of protein structures or an energy landscape, so that the structure latent in mathematical logic can reveal itself and evolve through the process. Each release is one step in that evolution. The Evolution page will make the path visible, including the paths AI chooses as it explores how the Atlas might develop.
The Research page gathers our latest results, drawn from an open-problem and conjecture library that we curate ourselves. We will keep connecting open questions to this library and working through them. Over time, we hope this will lay stronger foundations for the next stage of formal AI for mathematics. We are also glad to share that we have already solved some of these conjectures. The next few posts will go deeper into what we found.
Atlas: https://t.co/DedN5c7isU
We have watched formalization become one of the most important and indispensable parts of AI for math. Models can now produce vast amounts of mathematics that look remarkably plausible; what ultimately makes any of it trustworthy is handing it to a kernel for verification. We believe that step has moved from a useful finishing touch to the center of the whole endeavor. That belief is why we are building trureturing: an append-only ledger of mathematical truth in which a proposition is admitted only after kernel verification, with zero `sorry`, no `native_decide`, and axiom closure contained in `{propext, Classical.choice, Quot.sound}`. Once a module is frozen, it stays frozen. Later work may import it, but cannot rewrite it. The frozen ledger already includes the golden-integer tower, with the unit group `≃* ℤ × Multiplicative (ZMod 2)`, Fibonacci/Lucas bridges, and prime splitting mod 5, alongside zeta–Gibbs and entropy nodes. Every node is kernel-checked and content-addressed.
This week, that path led us to TauCeti. By its own public description, TauCeti is an AIs-welcome Lean library downstream of Mathlib: AI handles implementation and review, while humans write the roadmap and review rubric. When we started building trureturing, we did not know about TauCeti and had not collaborated with the project. Discovering another project working from the same underlying idea, in its own way, felt like a good sign that AI-written, kernel-verified mathematics is becoming a real way to work. We introduced ourselves this week in their public issue #5107.
If you are also working on AI-written formal mathematics, the water's fine. Come on in.
Repo: https://t.co/B9eEqXB8C5
Our hello to TauCeti: https://t.co/I6zItbfhuo
In trureturing, as we work through our derivations, we keep turning parts of them into mathematics that can be formalized on top of mathlib. Some of that turns out general enough to flow back into mathlib itself, and it makes us happy when it does.
A recent example: two of our lemmas were merged into Mathlib/NumberTheory/Wilson.lean. For a prime p with p % 4 ≠ 3, ((p−1)/2)! is an explicit square root of −1 modulo p — mathlib had the existence theorem and the converse, and now it also carries the concrete witness. The identity underneath holds for every odd p, not only primes:
(p−1)! = (−1)^((p−1)/2) · (((p−1)/2)!)² in ZMod p
which is the usual pairing step in Wilson's theorem.
What we're really after is broader participation and a lasting academic contribution — mathematics that other people can build on and check for themselves. We'd love more people to see what we're doing in trureturing and take part.
https://t.co/B9eEqXB8C5
Another stage of our work has now been published.
The work we have in peer review has been moving, one paper at a time, toward its final stages. The process has been genuinely interesting, and it has also been painful in ways that are hard to explain from the outside. There is a quiet kind of exhaustion in checking a proof again, waiting through another round of review, finding a gap after believing you were finished, and returning to the same argument with a little less certainty and a little more care.
We have been using ChatGPT for more than a year. We started close to zero and have slowly found a few results that we can stand behind. This paper is one small record of that journey and of how we have been using AI in our own scientific work. Its scope is narrow: one normalization problem, with claims we have checked carefully. For us, it also documents what became possible after spending a long time trying ideas and checking the details, including several restarts.
We think research may become more open to people who have not followed the usual route. Perhaps more people will get a real chance to learn by working on a question they care about. We wonder whether AI tools may lower some barriers to knowledge, including parts of advanced mathematics that have usually required university training. The boundary around the word “specialist” may loosen too. There is also an active discussion about whether foundation models may replace specialized models in more settings. Research may be approaching a major change; we do not yet know how far it will go, but we want to keep watching and working through it.
Our newly published paper is titled “Canonical Zeckendorf Normalization and Sharp Iteration Depth of the Berstel Adder.” It appears in the peer-reviewed journal RAIRO – Theoretical Informatics and Applications, volume 60 (2026).
Zeckendorf representation is a numeral system whose place values are Fibonacci numbers. Every nonnegative integer has a unique representation as a sum of non-adjacent Fibonacci numbers, so its 0-1 digit string has no adjacent 1s. When two such representations are added digit by digit, the intermediate word can contain 2s and adjacent 1s. It then has to be returned to its unique canonical form.
The paper studies that normalization problem through the classical Berstel adder. For genuine digitwise sums of two admissible Zeckendorf inputs of length n, read from the high Fibonacci positions toward the low positions, repeated Berstel recoding reaches the greedy Zeckendorf form in a worst-case depth of exactly ⌈n/2⌉. This bound is sharp, and the maximum is attained using the input’s actual significant length, with no leading-zero padding.
Reading in the opposite direction, from low positions toward high positions, has a fundamentally different behavior. No deterministic one-pass finite-state transducer, reading in that order and producing output sequentially with bounded terminal output, can always return the canonical Zeckendorf form. The paper proves a stronger quantitative obstruction: for any fixed amount of lookahead, even a given low-order output digit can remain undecided. The asymmetry between the two directions is the part that stayed with us after the formal statements were complete.
For us, this paper carries the memory of many ordinary hours. Some were satisfying. Some were spent wondering whether a proof was worth pursuing, or whether an error would appear as soon as someone else looked closely. That uncertainty is still with us after publication. Other people can now examine the work closely and decide whether there is anything here to build on. That is enough for this stage.
We would like to collaborate with people interested in mathematical reasoning, numeration systems, and AI for science. We also have a batch of papers that we hope to submit to arXiv. We are new users and need endorsement for submissions in the cs and math categories. Please look through our GitHub first and decide for yourself whether the work is worth endorsing. We would also be glad to hear from anyone who sees a useful way to work together.
GitHub: https://t.co/Mt7OYdKK0I
DOI: https://t.co/T7RT1kE5Yo
Toward AI for mathematics, and a little more.
As we worked more deeply with AI, one question kept returning: when a machine gives us a result, how do we know it is correct, and how should we judge its importance? Correctness and evaluation came before output.
We followed that question in two directions. One was orchestration: fkst (https://t.co/3ZDv2rS7Ol) coordinates AI agents under a fixed constitution and keeps their work traceable to its sources. The other was mathematics as a proving ground, where Lean lets us check what we think we have found.
The clearest record is in three repositories, including the mistakes and corrections.
automath (71★, ~9,200 commits) is an auditable theory compiler. It starts from one forced constraint: observe a system through a finite binary window and retain only the readouts that remain stable as the window widens. Those stable readouts lead to the golden-mean shift with characteristic equation x² = x + 1. The project develops the consequences in Lean 4 and in manuscripts.
The repository contains 23,304 theorem and lemma declarations and about 302,000 lines, with zero user-declared axiom, sorry, or admit; a CI audit checks that condition. Of 12,989 labeled manuscript claims, 7,877 (60.6%) are matched to a Lean declaration. I'd rather quote that number than a badge.
Across twelve manuscripts, we have submission records, including portal IDs issued by DCDS-A and the Journal of Number Theory. One revision was resubmitted after a referee report. So far, there have been zero acceptances and two recorded rejections, and none of the manuscripts has an arXiv posting or DOI. The repository includes records of both rejections and of two theorem defects that formalization caught after prose review missed them.
newmath tested the same engine without mathlib. It rebuilt the interfaces it used, from equality through the real numbers, instead of importing them. The repository contains 38,065 theorem declarations across 649,000 lines of our own Lean; 1,837 of those declarations were checked by Lean during one 72-hour stretch.
We then examined what that volume consisted of. Much of it came from mechanically generating variations of existing statements by echoing parameters or expanding arity. Some theorem shapes had already been exhausted. A clean build and a passing axiom check did not by themselves make the corpus useful. Producing 38,000 theorems is how we learned that the bottleneck was never production. It was selection.
That lesson changed the workflow. trureturing is an append-only, hash-chained ledger for theorem freezes. Each freeze binds the theorem's statement IDs, axiom closure, source blob, origin commit, and toolchain bytes. Its 23 lint rules block a merge if a closed theorem depends on an unproved result, a freeze payload fails an exact byte match, or the prose mirror has drifted from the formal statement. During its first three weeks, the repository recorded 441 PRs, of which 410 were merged, and 90 frozen modules containing 1,052 declarations.
The ledger is meant to support a dependency graph showing what Lean has checked and how the concepts connect. If a concept keeps recurring across the graph, we want a way to record our confidence that it points to something more general without presenting that confidence as a theorem.
We are also beginning to apply this approach to biology, including DNA sequence data, where we have seen patterns worth investigating. One hypothesis is that microscopic and macroscopic systems can be studied with the same question: how often does a pattern appear as a projection? That is a belief, not a result, and we will hold it to the same standard as the rest.
The repositories are public because we want people to inspect the work and point out where it fails. https://t.co/qcQqDdVyXF
Hi Dominik — I'm Wenlin, a PhD student working on AI at NUS. Your posts on getting the n=3 Kemeny hardness result with GPT and then formalizing it in Lean are the closest thing I've seen to how we actually work, so I wanted to reach out.
I run a project called Omega Institute with Haobo Ma, the CEO of ChronoAI — really just the two of us, betting early on AI-driven mathematics. In one line: we formalize math in Lean, lay the derivations out as a dependency graph, and mine that graph for relationships nobody had noticed. It runs as an automated pipeline that's now producing a stack of papers heading to journals and arXiv.
Looking at your GitHub — SocialChoiceLean, HardnessReductionsLean, KemenyHardnessLean — you're building exactly the kind of Lean corpus we've spent the last year building infrastructure around. You've written about how fragile it is to shepherd LLMs through these reductions and how hard they are to simplify. That's the specific problem we attack: an adversarial agent that tries to break each proof before it's accepted, plus an append-only "truth ledger" that only admits machine-checked results, so an LLM-generated corpus keeps growing without silently rotting.
So here's a concrete thing I'd love to try together: put your social-choice / hardness Lean corpus behind our verification-and-ledger pipeline, so your reductions become one growing, provenance-tracked, drift-proof library instead of separate repos — and then run our graph-miner over the voting axioms to see whether it surfaces any unnoticed relationships between the impossibility results. Your mathematics, our accumulation engine. I'd treat it as an experiment, not a promise.
And one practical ask: we have a pipeline of papers heading to arXiv and are brand new there, so we need an endorsement to submit under the cs categories — from your record you'd be eligible. I'd rather you look at our GitHub first (https://t.co/qcQqDdVyXF) and only endorse if it seems worth it.
Either way, thank you for working in the open. It's been genuinely useful to watch.