The source reports κ(q)=1 for every nonzero W23 pair label and a lifted-equivalence argument for compatible retractions. Nonretractive carrier enlargement with controlled pair-image connectivity remains viable; one explicit M3 construction is reported as a boundary example, not a general gadget.
Route status · Narrowed routeUniversal algebra · finite lattice theory · finite group intervals
Finite Lattice Representation Problem
Collaboration betaEvery finite lattice would be representable if one meet-irreducible deletion gadget could always be built. A competing route would disprove the statement by ruling out the seven-element W23 lattice in every finite group interval. The packet narrows both routes without finishing either.

Research problem
Exact mathematical statement
Determine whether every finite lattice L is isomorphic to the congruence lattice of some finite algebra A:
A positive resolution must give a finite representation for every finite lattice and exclude extra congruences. A negative resolution must exhibit one finite lattice and exclude every finite algebra, not only bounded carriers or selected construction families. The governing source explicitly reports that neither endpoint is completed.
Problem infographic
Problem at a glance

Current mathematical picture
Where work on Finite Lattice Representation Problem stands
Selected route highlights from the mathematical source. This is not yet a complete mathematical inventory.
The source reports that a uniform finite representation construction for deleting any proper meet-irreducible is equivalent to the universal affirmative target.
Evidence posture · Source-reported route statement · dependencies incompleteWork mapped so far
Finite Lattice Representation Problem in numbers
- Argument development
- 887 · 72%
- Explored or eliminated routes
- 74 · 6%
- Computational analysis
- 62 · 5%
- Open obligations
- 67 · 5%
- Definitions and setup
- 145 · 12%
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
Construct the general nonbottom meet-irreducible deletion gadget or an equivalent finite exact pair-generation construction with a terminating obligation order.
Suggested move: Test one explicit nonbottom deletion by a nonretractive attachment, enumerate every new pair type, and prove a finite rank decreases rather than recording only a solver outcome.
What would count as progress
- Supply a complete argument with every imported premise identified.
- Survive an independent attempt to falsify the proposed step.
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.
Explored alternatives
Other routes
The source reports κ(q)=1 for every nonzero W23 pair label and a lifted-equivalence argument for compatible retractions. Nonretractive carrier enlargement with controlled pair-image connectivity remains viable; one explicit M3 construction is reported as a boundary example, not a general gadget.
Route status · Narrowed routeThe reported interval classification is coatomistic away from the exceptional top, while the exceptional-top Bell-number count cannot match W23's seven elements and three coatoms. Modified or folded signalizers with multiple asymmetric extension sheets, non-pure-diagonal inputs, and arbitrary finite group intervals remain outside that exclusion.
Route status · Narrowed routeMore ways to contribute
Open questions
Additional prepared tasks for exploring this research frontier.
Construct a finite carrier-changing deletion witness that promotes exactly the required joins, checks every new pair, and proves termination for arbitrary finite input data.
Suggested move: Resolve the exact source-reported obligation without treating it as an established negative result.Sourced mathematical context
The known mathematical landscape
The universal question whether every finite lattice is the congruence lattice of a finite algebra remains open in the cited first-party research program. The literature isolates one unresolved lattice among those of size at most seven and gives an equivalent finite-group interval formulation. The current Agda work checks partial theory and selected certificates but explicitly does not claim a solution.
[2][3]What the literature has established
Selected external milestones in reverse chronological order, with their evidence posture.
Authoritative summaryA first-party project update reports a machine-checked Agda corpus for the problem, partial methods, and selected representation certificates while explicitly stating that the tree has not resolved the…[3] PreprintDeMeo showed that every lattice with at most seven elements except one has a known finite-algebra representation and studied restrictions on the remaining case; this isolates a smallest unresolved example…[2] Peer reviewedPálfy and Pudlák proved that the universal finite-algebra representation question is equivalent to asking whether every finite lattice is an interval in the subgroup lattice of a finite group.[1]
Mathematical neighborhood
Related results and reusable starting points
The universal finite-algebra representation question is equivalent to universal representation of finite lattices as intervals in subgroup lattices of finite groups.
[1][2]The remaining seven-element lattice is a concrete smallest unresolved test case, but resolving that one lattice alone must be interpreted through the cited reduction framework before drawing a conclusion about the universal problem.
[2][3]Formal and computational footholds
Existing statements, libraries, computations, and datasets that can shorten the next serious attempt.
- formal library support · partial resource linkedagda-algebras FLRP modules
The first-party project page links type-checked Agda statements of the problem and two thesis methods plus selected representation-certificate modules. It explicitly reports that the corpus does not resolve the universal problem.
[3]
Formalization opportunities
Lean work can make these reusable foundations precise without being presented as a proof of the core problem.
- Formalization targetThe cited formal corpus does not contain a checked universal construction for every finite lattice or a checked finite counterexample excluding every finite algebra.
- Formalization targetThe current work's exact W23 labeling and diagram were not aligned automatically with every external L7 label.
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
1 of 8 1 - reduction
2 of 8 2 - lemma
1 of 8 1 - computational claim
1 of 8 1 - equivalence
1 of 8 1 - negative result
1 of 8 1 - special case
1 of 8 1
Current research mapThe conjecture, retained reductions, explored limitations, and open questions represented in this overview.24 displayed rows · 2 routes included
- retained route statementDoes every finite lattice occur as the congruence lattice of a finite algebra?
- retained route statementCurrent reductionintermediate
- retained route statementClosing targetintermediate
- retained route statementMeet-irreducible deletion endpointintermediate
- retained route statementW23 excluded through eight pointsintermediate
- retained route statementW23 algebra-to-group reductionintermediate
- retained route statementPure-diagonal signalizer exclusionintermediate
- retained route statementBottom deletion by quotientintermediate
- Recorded relationshipThe source reports this as a route toward the conjecture; missing or unaudited premises remain and the reduction does not itself prove the target.supports · reported by source
- Recorded relationshipThis source-reported claim supports the retained route only within its stated, unaudited scope.supports · reported by source
- Recorded relationshipThis source-reported claim supports the retained route only within its stated, unaudited scope.supports · reported by source
- Recorded relationshipThis source-reported claim supports the retained route only within its stated, unaudited scope.supports · reported by source
- Recorded relationshipThis source-reported claim supports the retained route only within its stated, unaudited scope.supports · reported by source
- Recorded relationshipThis source-reported claim supports the retained route only within its stated, unaudited scope.supports · reported by source
- DerivationThe source reports that completing the closing target would advance the reduction to the main conjecture; this remains an informal route, not a verified derivation.proposed
- Useful failureRank-two Boolean-cut separation and compatible retractive repairreported failure
- Useful failurePure-diagonal signalizer familyreported failure
- Research targetConstruct the general nonbottom meet-irreducible deletion gadget or an equivalent finite exact pair-generation construction with a terminating obligation order.open
- Research targetExclude every remaining proper-projection configuration in all three W23 socle cases, including both simple and nonsimple socles where current results do not apply.open
- Research targetTurn the finite W23 certificates into an embedding-independent obstruction or else find a complete positive carrier certificate beyond the current bound.open
- Research targetGeneral finite deletion gadgetopen
- ComputationThe current work describes two search implementations and a separate checker for every exact W23 embedding on four through eight points, with 122 stored representatives in degrees six through eight.Source-reported finite conclusion: every algebra representing W23 has at least nine points; no degree-nine-or-higher or unbounded nonrepresentation claim is made. · reported unreproduced
- Narrowed routeRank-two Boolean-cut separation and compatible retractive repairThe source reports κ(q)=1 for every nonzero W23 pair label and a lifted-equivalence argument for compatible retractions. Nonretractive carrier enlargement with controlled pair-image connectivity remains viable; one explicit M3 construction is reported as a boundary example, not a general gadget.
- Narrowed routePure-diagonal signalizer familyThe reported interval classification is coatomistic away from the exceptional top, while the exceptional-top Bell-number count cannot match W23's seven elements and three coatoms. Modified or folded signalizers with multiple asymmetric extension sheets, non-pure-diagonal inputs, and arbitrary finite group intervals remain outside that exclusion.
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
2 approaches have 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.
- Supply a complete argument with every imported premise identified.
- Survive an independent attempt to falsify the proposed step.
Continue the mathematics
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Finite Lattice Representation Problem · ready to start
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Every finite lattice would be representable if one meet-irreducible deletion gadget could always be built. A competing route would disprove the statement by ruling out the seven-element W23 lattice in every finite group interval. The current work narrows both routes without finishing either.
- 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.
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Sources and references3 cited works · next context review by Nov 30, 2026
The mathematical context was checked on Aug 30, 2026. Status can be refreshed sooner after a material result or claim.
- 1Congruence lattices of finite algebras and intervals in subgroup lattices of finite groupspeer reviewed result · Péter Pál Pálfy, Pavel Pudlák · Algebra Universalis · 1980 · DOI 10.1007/BF02483080 · MR MR0593011 · accessed Aug 30, 2026
- 2Congruence lattices of finite algebrassurvey or monograph · William J. DeMeo · University of Hawai'i at Mānoa doctoral thesis; arXiv · 2012 · ARXIV 1204.4305 · accessed Aug 30, 2026
- 3Universal algebra and lattice theoryauthoritative webpage · William J. DeMeo · William J. DeMeo · accessed Aug 30, 2026
Important qualifications
- The current-status source is a researcher's maintained first-party project page rather than a peer-reviewed status survey; its claims are paired with the foundational paper and 2012 thesis and are not treated as proof of a resolution.
- The exceptional seven-element lattice is called L7 on the current project page and has also appeared under other local labels; this record does not assert that every label denotes the current work's exact W23 object without a separate diagram-level alignment.
- The linked Agda corpus formalizes the problem and partial methods and checks selected representation certificates; the source explicitly says it has produced no new mathematics resolving the problem.
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