Universal algebra · finite lattice theory · finite group intervals

Finite Lattice Representation Problem

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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 packet narrows both routes without finishing either.

finite latticesLfinite algebraAConAL
Known results and sources
Open-research thumbnail with a finite lattice on the left, a finite algebra carrier on the right, and two incomplete routes branching through deletion and W23 group intervals.
The packet narrows both a universal construction route and a W23 obstruction route; neither reaches a full endpoint.

Research problem

Exact mathematical statement

Determine whether every finite lattice L is isomorphic to the congruence lattice of some finite algebra A:

finite latticesL,finite algebraAConAL.\forall\text{ finite lattices }L,\;\exists\text{ finite algebra }\mathbf A \quad\operatorname{Con}\mathbf A\cong L.

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

Four-panel source-bound diagram of the exact finite-lattice target, the meet-irreducible deletion route, the W23 finite-group route, and the two unresolved endpoints.
Exact reductions and bounded exclusions organize the attack, but the universal deletion gadget and complete W23 group exclusion remain open.

Current mathematical picture

Where work on Finite Lattice Representation Problem stands

Open problem

Selected route highlights from the mathematical source. This is not yet a complete mathematical inventory.

Useful failureRank-two Boolean-cut separation and compatible retractive repair

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 route
Main reductionMeet-irreducible deletion endpoint

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 incomplete
Priority open bridgeConstruct the general nonbottom meet-irreducible deletion gadget or an equivalent finite exact pair-generation construction with a terminating obligation order.Task status · Ready to work on

Work mapped so far

Finite Lattice Representation Problem in numbers

1.2kretained lines of mathematical investigation1,235 in the current working snapshot
Argument development
887 · 72%
Explored or eliminated routes
74 · 6%
Computational analysis
62 · 5%
Open obligations
67 · 5%
Definitions and setup
145 · 12%
8selected mapped statements2routes investigated4open questions4contribution-ready tasks
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.

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

14 selected steps

Selected claims, active routes, useful failures, and open questions from the current research map. Arrows appear only for explicitly recorded relationships.

14 selected steps

Scroll horizontally to explore the route

Working route overview for Finite Lattice Representation ProblemA selected map of recorded claims, active routes, useful failures, open questions, and their explicit relationships. Search, filter, zoom, or pan within this page.Does every finite lattice occur as the congruence lattice of a finite algebra? — Depends on missing premiseDoes every finite latticeoccur as the congruencelattice…Current reduction — Depends on missing premiseCurrent reductionMeet-irreducible deletion endpoint — Depends on missing premiseMeet-irreducible deletionendpointW23 algebra-to-group reduction — Depends on missing premiseW23 algebra-to-groupreductionBottom deletion by quotient — Depends on missing premiseBottom deletion by quotientClosing target — Depends on missing premiseClosing targetPure-diagonal signalizer exclusion — Depends on missing premisePure-diagonal signalizerexclusionW23 excluded through eight points — Depends on missing premiseW23 excluded through eightpointsRank-two Boolean-cut separation and compatible retractive repair — stoppedRank-two Boolean-cutseparation and compatibleretractive…Pure-diagonal signalizer family — stoppedPure-diagonal signalizerfamilyConstruct the general nonbottom meet-irreducible deletion gadget or an equivalent finite exact pair-generation construction with a terminating obligation order. — OpenConstruct the generalnonbottom meet-irreducibledeletion…Exclude every remaining proper-projection configuration in all three W23 socle cases, including both simple and nonsimple socles where current results do not apply. — OpenExclude every remainingproper-projectionconfiguration…Turn the finite W23 certificates into an embedding-independent obstruction or else find a complete positive carrier certificate beyond the current bound. — OpenTurn the finite W23certificates into anembedding-independent…General finite deletion gadget — OpenGeneral finite deletiongadget
Working claimActive routeOpen, active, or blocked questionUseful failure

Working overview, not proof. The map shows selected recorded relationships; more nodes or edges do not establish correctness or completion.

Explored alternatives

Other routes

2 recorded
Narrowed routeRank-two Boolean-cut separation and compatible retractive repair

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 route
Narrowed routePure-diagonal signalizer family

The 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 route

More ways to contribute

Open questions

Additional prepared tasks for exploring this research frontier.

4 featured tasks
01
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.
Ready to work on
02
Exclude every remaining proper-projection configuration in all three W23 socle cases, including both simple and nonsimple socles where current results do not apply.Suggested move: Prove one precise projection, normalizer, or local-action interface with all domain and invariance checks, without importing the quarantined product-descent or local-quotient claims.
Ready to work on
03
General finite deletion gadget

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.
Ready to work on
04
Turn the finite W23 certificates into an embedding-independent obstruction or else find a complete positive carrier certificate beyond the current bound.Suggested move: Mine the degree-seven and degree-eight closures for a common primitive-positive extra equivalence, then prove it for arbitrary embeddings or produce a new candidate with complete pair-forest evidence.
Ready to work on

Sourced mathematical context

The known mathematical landscape

Context collected Aug 30, 2026
Current statusOpen problem

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]
External progress

What the literature has established

Selected external milestones in reverse chronological order, with their evidence posture.

  1. 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]
  2. 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]
  3. 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]
3 cited sources2 related results or reductionsReferences

Mathematical neighborhood

Related results and reusable starting points

Current focusFinite Lattice Representation Problem
Equivalent formulationfinite subgroup-interval representation problem

The universal finite-algebra representation question is equivalent to universal representation of finite lattices as intervals in subgroup lattices of finite groups.

[1][2]
Dependency or reductionexceptional seven-element lattice

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.

6 standing statements2 proposed statements4 open questions2 narrowed routes
Statements by mathematical role8 selected mapped statements
  • theorem candidate1 of 81
  • reduction2 of 82
  • lemma1 of 81
  • computational claim1 of 81
  • equivalence1 of 81
  • negative result1 of 81
  • special case1 of 81
Selected mathematical clusters1 mathematical clusters
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

Priority open bridgeConstruct the general nonbottom meet-irreducible deletion gadget or an equivalent finite exact pair-generation construction with a terminating obligation order.

2 approaches have already been tested and narrowed. The task above is the current priority within the larger open route.

Evidence needed nextConcrete conditions for progress

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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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.

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Prepared starting pointConstruct the general nonbottom meet-irreducible deletion gadget or an equivalent finite exact pair-generation construction with a terminating obligation order.

Finite Lattice Representation Problem · ready to start

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Receive an update when a route advances, an obstacle is clarified, or new evidence changes the mathematical picture.

Research contextPrepared context for any AI agent

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
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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.

  1. 1
    Congruence 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
  2. 2
    Congruence 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
  3. 3
    Universal 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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