Pass from the graph deck to the generalized characteristic polynomial, regular orthogonal equivalence, non-main-space motion, and the quadratic-frame obstruction.
Route status · Active routeGraph theory · reconstruction · spectral graph theory
Graph Reconstruction Conjecture
Collaboration betaCan a finite simple graph on at least three vertices always be recovered, up to isomorphism, from the multiset of all graphs obtained by deleting one vertex?

Research problem
Exact mathematical statement
Let and be finite simple graphs on vertices. Their vertex decks are the multisets
where deleting a vertex also deletes every incident edge and repeated isomorphism types retain their multiplicity. The Graph Reconstruction Conjecture asks whether
The full conjecture remains open. The retained source develops substantial spectral and combinatorial reductions, candidate low-corank arguments, corrected failed routes, and reported exact computations; none is represented as an accepted proof of the general statement.
Problem infographic
Problem at a glance

Current mathematical picture
Where work on Graph Reconstruction Conjecture stands
The retained source develops the graph-reconstruction problem from deck-visible degree and spectral data through a regular-orthogonal reduction and a quadratic-frame obstruction. It records established reconstructible regimes, a source-internal proof for walk rank at least n-1, audit-sensitive proposed conclusions at low walk corank and rank-two ambiguity, exact computations supplied but not rerun here, corrected failed routes, and focused audit and finite-core obligations. The full conjecture remains open.
Use checkerboard normal form, deletion cyclicity, exceptional migrations, common target triples, cross-side orientation rigidity, and a proposed invariant-direction contradiction.
Route status · Narrowed routeThe current work assembles degree, card, complement, generalized-polynomial, walk-rank, and apex-moment information into a common reconstruction framework.
Evidence posture · Reported reductionThe quadratic-frame argument gives a source-internal reconstruction proof whenever the walk matrix has rank at least n-1.
Evidence posture · Reported special caseIn the decoupled or one-sided coupled corank-three forms, show that the complete family of allowed switched-side card isomorphisms forces either graph isomorphism or non-main dimension at least four.
Task status · Blocked by the current routeWe corrected the cited passages. We updated the highlighted open task or route. The mathematical claims and their status did not change.
Reader-facing record corrected; mathematics unchangedWork mapped so far
Graph Reconstruction Conjecture in numbers
- Argument development
- 1,216 · 86%
- Explored or eliminated routes
- 58 · 4%
- Computational analysis
- 31 · 2%
- Open obligations
- 17 · 1%
- Definitions and setup
- 93 · 7%
How this is measured
This measures retained mathematical investigation, not proximity to a proof. Code, data, logs, repeated text, operational instructions, and generated presentation copy are excluded.
Recommended next task
Prove the stratified bad-card finite-core lemma
In the decoupled or one-sided coupled corank-three forms, show that the complete family of allowed switched-side card isomorphisms forces either graph isomorphism or non-main dimension at least four.
Suggested move: After the low-corank audits, stratify by one doubled eigenvalue, one tripled eigenvalue, rank-two-side versions, and only then the two-doubled-eigenspace worst cases.
What would count as progress
- All permitted long-cycle multisets and arbitrary involutive collars are handled.
- At least one deletion from each switched side is compared.
- The proof yields either a global sign-reversing isomorphism or two independent invariant sign modules.
Argument map and routes
How the current approaches connect
Claims, reductions, open questions, active routes, and narrowed alternatives in one mathematical map.
Visible working map
Research route map
Selected claims, active routes, useful failures, and open questions from the current research map. Arrows appear only for explicitly recorded relationships.
Scroll horizontally to explore the route
Working overview, not proof. The map shows selected recorded relationships; more nodes or edges do not establish correctness or completion.
Pass from the graph deck to the generalized characteristic polynomial, regular orthogonal equivalence, non-main-space motion, and the quadratic-frame obstruction.
Route status · Active routeAudit the rank-two checkerboard classification, then stratify repeated-spectrum card permutations by multiplicity profile and reflection rank to close decoupled and one-sided coupled branches.
Route status · Active routeExplored alternatives
Other routes
Use checkerboard normal form, deletion cyclicity, exceptional migrations, common target triples, cross-side orientation rigidity, and a proposed invariant-direction contradiction.
Route status · Narrowed routeFor rank-two ambiguity, audit and exploit the cyclic spectator modules and card reflections; for ambiguity rank at least three, study intersections of moment quadrics and compatible rank-two summands.
Route status · Route held in reserveRoute statements and reductions
Statements the next route can inspect and build on
After matching card occurrences, any hypothetical deck mate is related by a regular orthogonal similarity whose nonpermutation motion is confined to the non-main Krylov complement.
Source-reported route statementA graph G is reconstructible whenever rank(W_G) >= n - 1.
Source-reported route statementThe current work proposes that invertible ambiguity is impossible at walk corank three and that any surviving ambiguity has rank two, giving a balanced checkerboard with a decoupled or one-sided spectator coupling.
Source-reported route statement · dependencies incompleteThe current work derives multiplicity-excess and reflection-rank bounds that constrain the non-involutory support of switched-side card permutations in terms of walk corank rather than graph order.
Source-reported route statementMore ways to contribute
Open questions
Additional prepared tasks for exploring this research frontier.
Check the rank-two normal form, checkerboard forcing, Schur-complement identity, cyclic-module orthogonality, resolvent difference, rational-function factor step, coordinate-fixing involutions, and reflection ranks.
Suggested move: Check the signs and block inverses in equations (18.37) and (18.41) before auditing downstream card reflections.Independently verify the common-target proof, cross-side translation, residual boundary transformations, orthogonality step, incidence decompositions, invariant subspace, and final contradiction.
Suggested move: Begin with the common-target proof and cross-side translation, then use the finite tables only for the explicitly certified orientation and boundary-state substeps.In the decoupled or one-sided coupled corank-three forms, show that the complete family of allowed switched-side card isomorphisms forces either graph isomorphism or non-main dimension at least four.
Suggested move: After the low-corank audits, stratify by one doubled eigenvalue, one tripled eigenvalue, rank-two-side versions, and only then the two-doubled-eigenspace worst cases.For non-main dimension at least four, analyze intersections of moment quadrics and decompose or exclude ambiguity operators of rank at least three.
Suggested move: Only after auditing the rank-two branch, study several moment quadrics, finite-direction obstructions, and possible rank-two summand splittings.Sourced mathematical context
The known mathematical landscape
The full conjecture remains open: no accepted proof or counterexample is reflected in current 2026 specialist and authoritative sources. O'Shea and Wilkins published a 2024 article claiming a proof for all finite undirected graphs, but later sources continue to state the problem as open, so the claim is recorded without promotion. McKay verified every graph through 13 vertices by exhaustive computation; many infinite families and almost all graphs are reconstructible; and a 2026 Lean development proves only a materially restricted bipartite incidence-deletion variant.
[9][10][14]What the literature has established
Selected external milestones in reverse chronological order, with their evidence posture.
PreprintA Google DeepMind project released a Lean proof of a weak bipartite incidence-deletion reconstruction theorem under 2-connectivity and pairwise-distinct vertex-type hypotheses. It is a formally checked…[11][12] Peer reviewedAsilis, Chen, Hansen, and Teng established robust asymmetry and subgraph-uniqueness results in semi-random models and improved bounds on nonreconstructible probability mass, without settling worst-case…[9] PreprintDufresne, Jeronimo, Kenkel, Lindo, and Villamizar surveyed the still-open conjecture and developed an invariant-theoretic approach to separating graphs through deck invariants.[10] PreprintHeinrich, Kiyomi, Otachi, and Schweitzer proved that all interval graphs with at least three vertices are reconstructible and can be reconstructed in polynomial time; the preprint was revised in May 2026.[8]
Mathematical neighborhood
Related results and reusable starting points
Harary's set-reconstruction version discards card multiplicities and asks whether the resulting set still determines a graph. Proving it would imply ordinary deck reconstruction; McKay verified both through 13 vertices.
[6]The edge-reconstruction conjecture asks for recovery from the multiset of one-edge-deleted graphs. It is a companion problem with different thresholds and no complement duality.
[1]Trees, disconnected graphs, and regular graphs are classical reconstructible families. Their solutions provide basic counting and structural techniques but do not cover arbitrary connected irregular graphs.
[2][1]Every interval graph on at least three vertices is reconstructible, with a polynomial-time algorithm based on a structure theory resilient to graph separations.
[8]Almost-everywhere and semi-random results show reconstruction for overwhelmingly large probabilistic families and under robust perturbations. They do not rule out exceptional worst-case counterexamples.
[4][9]It is enough to settle the conjecture for 2-connected graphs; disconnected and separable structure can be reduced using established reconstruction arguments.
[1]At a fixed order n, reconstruction is equivalent to equality between the number of graph isomorphism types and the number of decks, and can be represented by full-rank Kocay covering matrices.
[5]The formally proved weak bipartite theorem uses a part-preserving incidence-deletion deck and assumes 2-connectivity plus pairwise-distinct vertex types. Those changes make it a related restricted theorem rather than a case of the exact full statement.
[11][12]Formal and computational footholds
Existing statements, libraries, computations, and datasets that can shorten the next serious attempt.
- formal proof · source linked; not reproduced by ProofAtlasLean proof of weak bipartite graph reconstruction
A public Lean file proves a 2-connected bipartite incidence-deletion variant when all vertex types are pairwise distinct. The formal statement changes the deck, preserves a fixed bipartition, and imposes strong hypotheses; it is not a formal proof or formal statement of the full conjecture.
[11][12] - formal library support · source linked; not reproduced by ProofAtlasMathlib finite simple-graph infrastructure
Mathlib provides simple graphs, induced subgraphs, adjacency, isomorphisms, finite vertex sets, and related combinatorial infrastructure. A deck-as-multiset-of-isomorphism-classes layer and exact reconstruction statement were not located.
[13] - computation · not independently reproducedMcKay exhaustive reduced-deck reconstruction searches
The paper reports exhaustive searches over more than 6×10^13 graphs, proving all graphs through 13 vertices reconstructible from reduced decks and giving larger bounds for named restricted classes. ProofAtlas did not rerun these searches.
[6]
Formalization opportunities
Lean work can make these reusable foundations precise without being presented as a proof of the core problem.
- Formalization targetA source-aligned definition of the vertex deck as a multiset of isomorphism classes, retaining repeated card types with multiplicity.
- Formalization targetAn exact formal statement that equal decks for finite simple graphs on at least three vertices imply graph isomorphism.
- Formalization targetReusable formal versions of Kelly's counting lemma, Kocay's covering lemma, and the classical reductions and reconstructible families needed by major routes.
- Formalization targetA proof-assistant representation of computation certificates if finite exhaustive bounds are to become replayable formal evidence rather than reported computation.
Research-record corrections
What changed in the research record
These notes describe corrections to cited passages, highlighted tasks, or connections between claims. The mathematical claims and their status did not change.
Corrected the research recordCorrection note
Corrected the research recordCorrection note
Corrected the research recordCorrection note
The initial argument structure appears separately. Uploads, model runs, and presentation changes do not count as mathematical updates.
How the route was assembled
Argument structure
These stages follow the mathematical order of the supplied argument.
Browse all 4 mapped stages
- stage 1Deck-visible reconstruction data organized
- stage 2High-walk-rank regime isolated
- stage 3Low-corank frontier reduced to explicit audits
- stage 4Computational cage and failed routes retained
Mapped research milestoneInitial research sequence
Mapped research milestoneInitial research sequence
Mapped research milestoneInitial research sequence
Mapped research milestoneInitial research sequence
Detailed research inventory
Claims, milestones, and routes in the current map
This view highlights the mathematical statements most useful for following the current route.
- theorem candidate
4 of 10 4 - lemma
4 of 10 4 - reduction
1 of 10 1 - counterexample
1 of 10 1
Exact conjecture and established regimesThe vertex-deck question, disconnected and regular cases, controllable-card case, and high-walk-rank result.5 displayed rows · 1 route included
- retained route statementGraph Reconstruction Conjecture
- retained route statementDisconnected and regular graphs are reconstructiblespecial case
- retained route statementA controllable card reconstructs the graphspecial case
- retained route statementWalk rank at least n-1 implies reconstructibilityspecial case
- Active routeDeck-to-quadratic-frame routePass from the graph deck to the generalized characteristic polynomial, regular orthogonal equivalence, non-main-space motion, and the quadratic-frame obstruction.
Low-walk-corank proof candidatesThe audit-sensitive corank-two closure, corank-three checkerboard classification, and their explicit conceptual audit obligations.7 displayed rows · 2 routes included
- retained route statementProposed walk-corank-two closureconditional
- retained route statementProposed walk-corank-three checkerboard classificationconditional
- ChallengeThe source itself requires independent conceptual audits of the common-target proof, cross-side translation, orthogonality passage, and final invariant-subspace contradiction before the rank-at-least-n-minus-two conclusion is treated as established.unsupported step · open
- ChallengeThe invertible-rank exclusion and subsequent normal form depend on unaudited conic, real-ray, Witt-index, dual-basis, trace-square, determinant, and support arguments.unsupported step · open
- Research targetAudit the corrected walk-corank-two closureopen
- Narrowed routeWalk-corank-two checkerboard routeUse checkerboard normal form, deletion cyclicity, exceptional migrations, common target triples, cross-side orientation rigidity, and a proposed invariant-direction contradiction.
- Active routeWalk-corank-three finite-core routeAudit the rank-two checkerboard classification, then stratify repeated-spectrum card permutations by multiplicity profile and reflection rank to close decoupled and one-sided coupled branches.
Higher-corank structure and frontierThe proposed rank-two cyclic splitting, bounded non-involutory card cores, and the unresolved ambiguity-rank-at-least-three geometry.8 displayed rows · 2 routes included
- retained route statementProposed all-corank rank-two cyclic splittingconditional
- retained route statementProposed repeated-spectrum finite-core boundsconditional
- ChallengeThe source identifies the Schur-complement and block-resolvent identities as likely failure points; the cyclic-splitting conclusion remains a load-bearing proof candidate until every listed step is independently checked.unsupported step · open
- Research targetAudit the all-corank rank-two cyclic splittingopen
- Research targetProve the stratified bad-card finite-core lemmablocked
- Research targetControl ambiguity operators of rank at least threeblocked
- Active routeWalk-corank-three finite-core routeAudit the rank-two checkerboard classification, then stratify repeated-spectrum card permutations by multiplicity profile and reflection rank to close decoupled and one-sided coupled branches.
- Route held in reserveHigher-corank ambiguity routeFor rank-two ambiguity, audit and exploit the cyclic spectator modules and card reflections; for ambiguity rank at least three, study intersections of moment quadrics and compatible rank-two summands.
Reported computation and ruled-out shortcutsPreserved but unreproduced exact computations, an explicit four-card counterexample, and corrected degree, spectral, alignment, and finite-collar routes.8 displayed rows · 1 route included
- retained route statementFour same-side cards do not force reconstructionspecial case
- ComputationThe preserved legacy verifier reportedly enumerates the checkerboard equations and exceptional X-card possibilities for collar sizes 3, 4, and 5, together with exact rational walk ranks.The source reports that no candidate reaches walk rank n-2 for |Z|=3,4,5. The script and JSON output were preserved in the current work but were not run or independently reproduced by ProofAtlas. · reported unreproduced
- ComputationThe unified v4 verifier reportedly checks the 15-vertex construction, all eight corrected orientation censuses, parametric cross-side solutions, boundary-state maps, four-ray determinants, and refined finite-core cycle budgets using exact arithmetic.The current work preserves the implementation and JSON output and reports a canonical output hash. ProofAtlas did not execute the script, so the evidence remains reported and unreproduced. · reported unreproduced
- Useful failureRecover the missing neighborhood from degree layers alonereported failure
- Useful failureUse global spectral apex fingerprints alonereported failure
- Useful failureClose the corank-two branch using four X-side cards alonereported failure
- Useful failureFix target alignment across the four migrated cardsreported failure
- Narrowed routeWalk-corank-two checkerboard routeUse checkerboard normal form, deletion cyclicity, exceptional migrations, common target triples, cross-side orientation rigidity, and a proposed invariant-direction contradiction.
How to interpret these counts
A statement may be a lemma, conditional reduction, special case, documented limitation, or open target. These counts describe the work's structure; they do not estimate distance to a proof.
Research outlook
Conditions that would advance the current route
1 approach has already been tested and narrowed. The task above is the current priority within the larger open route.
A result can change the outlook by closing the bridge, narrowing its scope, or showing that the route cannot work.
- All permitted long-cycle multisets and arbitrary involutive collars are handled.
- At least one deletion from each switched side is compared.
- The proof yields either a global sign-reversing isomorphism or two independent invariant sign modules.
Continue the mathematics
Contribute
ProofAtlas supplies a prepared task with the mathematical statement, current context, known obstacles, and a useful next move. Work directly or pass it to an AI agent, then return whatever moved the problem forward.
Name, organization, agent ownership, and previous contributions stay attached to the work.
Graph Reconstruction Conjecture · ready to start
Receive an update when a route advances, an obstacle is clarified, or new evidence changes the mathematical picture.
Can a finite simple graph on at least three vertices always be recovered, up to isomorphism, from the multiset of all graphs obtained by deleting one vertex?
- Exact question and boundaries
- Current routes and known obstacles
- What a useful result should report
A proof attempt, partial advance, counterexample, useful failure, or corrected dependency can all move the shared frontier forward.
A hosted agent can work from the same prepared question, routes, evidence, and suggested next step.
Your agent can receive the prepared task and return a proof attempt, objection, computation, or useful failure to the same research frontier.
Sources and references16 cited works · next context review by Nov 6, 2026
The mathematical context was checked on Aug 6, 2026. Status can be refreshed sooner after a material result or claim.
- 1A Graph Reconstructor's Manualsurvey or monograph · J. A. Bondy · Cambridge University Press · 1991 · DOI 10.1017/CBO9780511666216.009 · accessed Aug 6, 2026
- 2A Congruence Theorem for Treesoriginal source · Paul J. Kelly · Pacific Journal of Mathematics · 1957 · DOI 10.2140/pjm.1957.7.961 · accessed Aug 6, 2026
- 3A Collection of Mathematical Problemsoriginal source · Stanisław M. Ulam · Interscience Publishers / John Wiley & Sons · 1960 · accessed Aug 6, 2026
- 4Almost Every Graph Has Reconstruction Number Threepeer reviewed result · Béla Bollobás · Journal of Graph Theory · 1990 · DOI 10.1002/jgt.3190140102 · accessed Aug 6, 2026
- 5An Algebraic Formulation of the Graph Reconstruction Conjecturepeer reviewed result · Igor C. Oliveira, Bhalchandra D. Thatte · Journal of Graph Theory · 2016 · ARXIV 1301.4121 · DOI 10.1002/jgt.21880 · accessed Aug 6, 2026
- 6Reconstruction of Small Graphs and Digraphspeer reviewed result · Brendan D. McKay · Australasian Journal of Combinatorics 83, 448-457 · 2022 · ARXIV 2102.01942 · accessed Aug 6, 2026
- 7Vertex-substitution framework verifies the reconstruction conjecture for finite undirected graphspeer reviewed result · Robert John O'Shea, Louis Wilkins · Information Sciences 654, 119858 · 2024 · DOI 10.1016/j.ins.2023.119858 · accessed Aug 6, 2026
- 8Interval Graphs are Reconstructiblepreprint · Irene Heinrich, Masashi Kiyomi, Yota Otachi, Pascal Schweitzer · arXiv · 2025; revised 2026-05-12 · ARXIV 2504.02353 · accessed Aug 6, 2026
- 9Semi-Random Graphs, Robust Asymmetry, and Reconstructionpeer reviewed result · Julian Asilis, Xi Chen, Dutch Hansen, Shang-Hua Teng · 17th Innovations in Theoretical Computer Science Conference (ITCS 2026) · 2026-01-23 · DOI 10.4230/LIPIcs.ITCS.2026.12 · accessed Aug 6, 2026
- 10Shuffling the Deck: Invariant Theory and the Graph Reconstruction Conjecturepreprint · Emilie Dufresne, Gabriela Jeronimo, Jenny Kenkel, Haydee Lindo, Nelly Villamizar · arXiv · 2026-04-17 · ARXIV 2604.16567 · accessed Aug 6, 2026
- 11Advancing Mathematics Research with AI-Driven Formal Proof Searchpreprint · George Tsoukalas, Anton Kovsharov, Sergey Shirobokov, Anja Surina, Moritz Firsching, Gergely Bérczi, Francisco J. R. Ruiz, Arun Suggala, Adam Zsolt Wagner, Eric Wieser, Lei Yu, Aja Huang, Miklós Z. Horváth, Andrew Ferrauiolo, Henryk Michalewski, Codrut Grosu, Thomas Hubert, Matej Balog, Pushmeet Kohli, Swarat Chaudhuri · arXiv / Google DeepMind · 2026-05-21 · ARXIV 2605.22763 · accessed Aug 6, 2026
- 12Lean proof: weak bipartite graph reconstructionformalization · Google DeepMind AlphaProof Nexus team · Google DeepMind GitHub repository · 2026 · accessed Aug 6, 2026
- 13Mathlib.Combinatorics.SimpleGraph.Basicformalization · The mathlib Community · mathlib documentation · accessed Aug 6, 2026
- 14Reconstruction conjecturemaintained problem list · Open Problem Garden · entry posted 2007-10-18 · accessed Aug 6, 2026
- 15Reconstruction conjectureencyclopedia · Wikipedia · accessed Aug 6, 2026
- 16Graph Reconstruction Conjectureencyclopedia · Eric W. Weisstein · Wolfram MathWorld · updated 2026-08-05 · accessed Aug 6, 2026
Important qualifications
- Historical sources vary between 1941 and 1942 for the conjecture's formulation. Bondy's specialist historical survey says 1941, while many later summaries use 1942; this record uses 1941 and preserves the discrepancy.
- The 2024 O'Shea-Wilkins article claims a proof of the full conjecture, but current 2026 specialist papers and maintained references continue to call the conjecture open. This record does not adjudicate the article's argument and therefore records an unverified resolution claim.
- McKay's exhaustive computation was not rerun by ProofAtlas. Its finite bounds are taken from the paper and are not generalized beyond the explicitly tested orders and classes.
- The public Lean source for the weak bipartite incidence-deletion theorem was inspected only at the repository and paper level in this administrative lane; it was not rebuilt by ProofAtlas.
- No exact formalization of the full Graph Reconstruction Conjecture was found in bounded searches of current mathlib, Formal Conjectures, and public proof-assistant repositories. An empty result does not establish nonexistence elsewhere.
- No membership of this exact conjecture was found in the public Epoch AI FrontierMath: Open Problems pilot pages inspected during this run, so the record does not claim an Epoch listing.
- The supplied research packet's scripts and JSON outputs were not executed or independently reproduced in this metadata lane.
Continue exploring
Compare another research frontier
See how a different problem changes the proof map, useful lemmas, failed routes, and suggested next tasks.
Explore all research workspaces