Plane topology · configuration geometry · analytic and spectral methods

Inscribed Square Problem

Collaboration beta

Must every simple closed curve in the plane pass through the four corners of a square? The current research follows configurations with three corners on the curve and the fourth inside. It reports a connected family across all source separations and a coupling that prevents the second configuration from being smaller than the first. Both sizes can still collapse to zero. Conditional fixed-action, detector and regular-subclass methods remain separate routes, and none currently covers every Jordan curve.

C2a Jordan curve, p,q,r,sCdistinct forming a square
Known results and sources
Illustration: A diagram accompanying the open question of four distinct square vertices on a planar Jordan curve.
Illustration: Must every simple closed planar curve contain the four vertices of a square? The full question remains open.

Research problem

Exact mathematical statement

Does every planar Jordan curve contain four distinct vertices of a Euclidean square? Here a Jordan curve is a simple closed curve in the plane. No smoothness, area-zero, genericity, prescribed cyclic source order, or continuous choice of a square is assumed.

C2a Jordan curve,p,q,r,sCdistinct forming a Euclidean square.\forall C\subset\mathbb R^2\text{ a Jordan curve},\quad\exists p,q,r,s\in C\text{ distinct forming a Euclidean square}.

The current source leaves this full statement unresolved. Rectangle results at other shapes and results for regular subclasses retain their narrower scope.

Problem infographic

Problem at a glance

Illustration: Four distinct points A, B, C and D of a simple closed plane curve form a square. Equal-side ticks and right-angle marks show the square constraints. The drawing is one example; the question concerns every Jordan curve. The retained source leaves the general target unresolved.
Illustration: Must every planar Jordan curve contain four distinct vertices of a Euclidean square? No boundary regularity, area-zero, genericity, prescribed source order or selector assumption is added to that question. The drawing supplies one example; the retained source reports no complete proof of the general statement.

Current mathematical picture

Where work on Inscribed Square Problem stands

Open problem

recorded v52 boundary-continuum, inherited fixed-action and detector frontiers; all-Jordan square existence remains open. Retained v8/v20 objects and inactive history remain explicit, with current source corrections and proof-owner dependencies preserved.

Leading routeThree-contact continuum and total collision

The boundary route starts from square-freeness and HUG-WRAP, reaches an exact global three-contact continuum, and then has geometric, degree/return, size-coupling and cap-approximation branches. Its live work is to exclude same-continuum total collision, handle the conditional return alternatives, or obtain global cap compatibility. All-zero return degrees and the distinct scale/chord-parameter regimes remain; no path, unnamed action comparison or complete all-Jordan terminal is supplied.

Route status · Active route
Main reductionElegant contour-shell engine

The source reports a lossless lowering measure and explicit shell currents; B0/B1 must still retain controlled-sector mass and accumulate defects into a valid relation, capping/stress transition, or excluded zero model.

Evidence posture · Source-reported route statement · dependencies incomplete
Priority open bridgeB45-S

Reconstruct each smooth spectral, polygon-simplicity and marked-source import at its exact scope; do not treat project strain formulas as external theorems or QSI implementation.

Task status · Ready to work on
Research-record correctionResearch-record correction

We corrected supporting details in the research record. The mathematical claims and their status did not change.

Reader-facing record corrected; mathematics unchanged

Work mapped so far

Inscribed Square Problem in numbers

5.1kretained lines of mathematical investigation1,233 in the current working snapshot
Argument development
4,095 · 80%
Explored or eliminated routes
140 · 3%
Computational analysis
103 · 2%
Open obligations
402 · 8%
Definitions and setup
370 · 7%
23inventoried working statements10routes investigated33open questions33contribution-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

28 selected steps

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

28 selected steps

Scroll horizontally to explore the route

Working route overview for Inscribed Square ProblemA selected map of recorded claims, active routes, useful failures, open questions, and their explicit relationships. Search, filter, zoom, or pan within this page.Every planar Jordan curve contains a nondegenerate square — Depends on missing premiseEvery planar Jordan curvecontains a nondegeneratesquareElegant contour-shell engine — Depends on missing premiseElegant contour-shell engineParallel boundary, fixed-action and detector routes — Depends on missing premiseParallel boundary,fixed-action and detectorroutesRadial/capping carrier and typed-transfer engine — Depends on missing premiseRadial/capping carrier andtyped-transfer engineSource-localized self-stress/model engine — Depends on missing premiseSource-localizedself-stress/model engineA terminal on one complete regular charged leaf — Depends on missing premiseA terminal on one completeregular charged leafActual positive response remains an additional premise — Depends on missing premiseActual positive responseremains an additionalpremiseAN-22--AN-29 quantitative corridor and target-current packet — Depends on missing premiseAN-22--AN-29 quantitativecorridor and target-currentpacketClose every remaining Jordan-curve alternative — Depends on missing premiseClose every remainingJordan-curve alternativeCoupling removes decreasing size, not total collapse — Depends on missing premiseCoupling removes decreasingsize, not total collapseFinite variation results retain selected polygon and spectral risk — Depends on missing premiseFinite variation resultsretain selected polygon andspectral…Fixed action without a chosen square selector — Depends on missing premiseFixed action without achosen square selectorThree-contact continuum and total collision — activeThree-contact continuum andtotal collisionActual QSI and detector variation — activeActual QSI and detectorvariationRestricted primitive and positive-response routes — activeRestricted primitive andpositive-response routesComplete charged-family alternatives — activeComplete charged-familyalternativesRSE-2 / NR-437 — stoppedRSE-2 / NR-437UAP-1 / B45-G/R45-G / AGC-1 / AGC-2 — stoppedUAP-1 / B45-G/R45-G / AGC-1/ AGC-2AFC-1 / MOM-1 — stoppedAFC-1 / MOM-1Representation-level, regularity, and calibrated-moment shortcuts — stoppedRepresentation-level,regularity, andcalibrated-moment…B51-C/R51-C — OpenB51-C/R51-CB51-R/R51-R — OpenB51-R/R51-RB51-T/R51-T — OpenB51-T/R51-TB45-P/R45-P — OpenB45-P/R45-PB47-E/R47-E — OpenB47-E/R47-EB49-C/R49-C — OpenB49-C/R49-CB49-M/R49-M — OpenB49-M/R49-MB45-G/R45-G — OpenB45-G/R45-G
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.

Active routeThree-contact continuum and total collision

The boundary route starts from square-freeness and HUG-WRAP, reaches an exact global three-contact continuum, and then has geometric, degree/return, size-coupling and cap-approximation branches. Its live work is to exclude same-continuum total collision, handle the conditional return alternatives, or obtain global cap compatibility. All-zero return degrees and the distinct scale/chord-parameter regimes remain; no path, unnamed action comparison or complete all-Jordan terminal is supplied.

Route status · Active route
Active routeActual QSI and detector variation

The unmarked detector route requires actual QSI-1 implementation, including coherent natural maps and lifted/localized values, before its first natural image threshold and angular comparison can be used at the displayed finite-constructible scope. Marked QSL-1C/AI-RISK remains a separate unresolved source interface. Positive profile value or endpoint increase does not force positive square-angle slope, and abstract flat models do not settle actual geometric realization or preservation of first detection through switches.

Route status · Active route
Active routeRestricted primitive and positive-response routes

The primitive route uses the displayed common-support ambient budget or finite hull-area variation with selected simple polygons, retaining AI-CPL and AI-RISK; UAP-1 retires the unrestricted universal-budget construction while restricted or square-free-conditional constructions remain. The distinct smooth-response route uses its GL-SM-based formulas only with actual positive bounded-probe or controlled endpoint variation. Critical primitive regularity, unsigned hull accumulation, weak averages or a positive spectral value do not supply those missing inputs or full-target exhaustion.

Route status · Active route
Active routeComplete charged-family alternatives

The charged-family route retains both cofinal exact-critical states and one regular full-tail spine at the source's fixed-action scope. The regular branch keeps physical-cap variation or concentration, both stopping alternatives, complete frontier or coherent corridor, and bounded/unbounded energy and cap-product cases. Its circumcircle terminal needs actual full-tail absolute variation or physical cap uniform integrability on one coherent family. First-hit graph estimates, projected inverse concentration, kinematic examples or tangent concurrence do not supply all missing premises or COV-1.

Route status · Active route
Active routeRetained v20 route: Two-center analytic corridor

The retained v20 source reports this route and its unresolved interfaces. Its mathematical statement remains historical recorded evidence; the v52 update does not infer completion from omission. Source-reported live engine with explicit unresolved interfaces; it is not a completed route to the conjecture.

Route status · Active route
Active routeRetained v20 route: R-E continuous-lift bypass

The retained v20 source reports this route and its unresolved interfaces. Its mathematical statement remains historical recorded evidence; the v52 update does not infer completion from omission. Source-reported live engine with explicit unresolved interfaces; it is not a completed route to the conjecture.

Route status · Active route
Active routeRetained v20 route: Elegant contour-shell route

The retained v20 source reports this route and its unresolved interfaces. Its mathematical statement remains historical recorded evidence; the v52 update does not infer completion from omission. Source-reported live engine with explicit unresolved interfaces; it is not a completed route to the conjecture.

Route status · Active route
Active routeRetained v20 route: Radial alternating end transfer

The retained v20 source reports this route and its unresolved interfaces. Its mathematical statement remains historical recorded evidence; the v52 update does not infer completion from omission. Source-reported live engine with explicit unresolved interfaces; it is not a completed route to the conjecture.

Route status · Active route
Active routeRetained v20 route: Two-center self-stress/model route

The retained v20 source reports this route and its unresolved interfaces. Its mathematical statement remains historical recorded evidence; the v52 update does not infer completion from omission. Source-reported live engine with explicit unresolved interfaces; it is not a completed route to the conjecture.

Route status · Active route

Explored alternatives

Other routes

1 recorded
Useful but insufficientHistorical marked-endpoint and vineyard route

The earlier marked-endpoint and vineyard arguments do not close the current source interfaces. Marked QSL-1C / AI-RISK-1 remains a separate qualification, while the alternative unmarked QSI-1 route is still implementation pending. The earlier claim that marked endpoints were not the controlling obstruction does not discharge either interface.

Route status · Useful but insufficient

Route statements and reductions

Statements the next route can inspect and build on

Route statementAN-22--AN-29 quantitative corridor and target-current packet

The source labels AN-22--AN-24 and AN-26--AN-29 as proved at their stated scopes and AN-25 as a proved reduction, yielding little-Besov/VMO regularity, deep packet corridors, a network-or-spiral reduction, and compact target-current/multipole data without global closure.

Source-reported route statement · dependencies incomplete
Route statementRadial/capping carrier and typed-transfer engine

The source retains an odd relative radial class and a conditional carrier-end cocycle, but B2a and RC-21 still require a proper elegant carrier, a base-times-target three-current, cap/slicing identities, anchor transport, and all boundary faces.

Source-reported route statement · dependencies incomplete
Route statementSource-localized self-stress/model engine

The source reports exact finite-dimensional stress data and model exclusions while retaining source packet-chain localization and propagation under source, frame, phase, and scale control as unresolved.

Source-reported route statement · dependencies incomplete
Route statementElegant contour-shell engine

The source reports a lossless lowering measure and explicit shell currents; B0/B1 must still retain controlled-sector mass and accumulate defects into a valid relation, capping/stress transition, or excluded zero model.

Source-reported route statement · dependencies incomplete
Route statementParallel boundary, fixed-action and detector routes

The source separates a boundary-continuum tree, an inherited fixed-action tree and an unmarked detector tree. The boundary tree has an unresolved total-collision or return terminal; the fixed-action tree retains the exact-critical and regular full-tail alternatives; the detector tree needs QSI-1 and an additional positive local-slope input. No exhaustion theorem covers every remaining Jordan curve.

Source-reported route statement · dependencies incomplete
Route statementClose every remaining Jordan-curve alternative

A route to the full target must provide an actual sufficient endpoint under its displayed premises and cover every remaining Jordan curve. Closing a boundary collision subcase, a single charged leaf, a geometric model, or a conditional detector branch is not the missing exhaustion theorem.

Source-reported route statement · dependencies incomplete
Route statementSeparate unmarked QSI and marked source risk

The source keeps two distinct upstream interfaces: an independent reconstruction of marked QSL-1C at AI-RISK-1 scope, and implementation of unmarked QSI-1 in the actual twisted periodic category with lifted endpoint, family-Hom, localization and coherent-gauge conditions. The older unqualified statement that the marked-endpoint problem is not controlling must not erase either live interface.

Source-reported route statement · dependencies incomplete
Route statementFixed action without a chosen square selector

At the source's accepted-root scope, every sufficiently deep state has a pointwise fixed-action consequence. This does not choose a continuous square, a detector, or an all-scale carrier. RSP-1 preserves cofinal exact-critical charged states as an alternative to a regular charged full-tail spine; neither can be discarded in favor of a convenient branch.

Source-reported route statement · dependencies incomplete
Route statementRetain source faces, both endpoint channels and physical scale

The inherited supplied-family arguments retain hits, no-hits, filler channels, source and action rims, both endpoint channels and every selected face. Normalized convergence does not supply physical cap control, source BV, uniform mass, a full positive-wall family map or a terminal for unbounded normalized lens mass.

Source-reported route statement · dependencies incomplete
Route statementA terminal on one complete regular charged leaf

CIV-1 gives charge collapse only from the stated weighted center/radius variation or physical cap uniform integrability on one full-tail regular spine. Projected inverse concentration, pointwise bounded energy, state-switching examples and tangent models do not supply that premise.

Source-reported route statement · dependencies incomplete
Route statementOne connected all-scale three-contact continuum

Under the source's square-free Jordan assumption and HUG-WRAP interface, BPG-1 supplies one connected closed configuration set with three actual boundary corners, the missing corner in the interior, the full angle range and retained compact positive-size crossings. It supplies no path, manifold structure, BV or action spine, continuous square selector, or unique endpoint. Rerooting need not preserve the chosen band; balanced compact subsets need not connect the signs.

Source-reported route statement · dependencies incomplete
Route statementSource order, return degree and positive caps

The source derives strict inradius/radius/hull-area obstructions and a return-degree formula on compact continua. Reverse source order forces a nonzero return degree; positive order can have all degrees zero. Cap hull area and angular advance do not control tangent action or an approximation rate. Return at chord parameter tending to one is terminal only if side length stays nonzero; parameter tending to zero permits narrow return.

Source-reported route statement · dependencies incomplete
Route statementCoupling removes decreasing size, not total collapse

For every sufficiently small prescribed eta, BMC-1 uses a compact connected size-floor set through a fixed core to couple a side-eta configuration with another side lambda at least eta whose missing corner lies on the first chord. B4P-1 produces four actual separated boundary points, not the four corners of one square. Both scales can tend to zero; no compatible choice across eta, nonzero final size, or terminal in every ratio/chord-parameter regime is supplied.

Source-reported route statement · dependencies incomplete
Route statementThe universal ambient budget is withdrawn

AGC-1/2 give sufficient bounds at their stated isotopy, length and incremental-budget scope. UAP-1 defeats the unrestricted universal bounded ambient budget using a square-containing zero-area Jordan example whose smooth approximants have unbounded primitive oscillation. Square-free-conditional and explicitly restricted constructions remain open. C0, Hofer, L2 or finite-q Lorentz strain cannot replace the endpoint cost.

Source-reported route statement · dependencies incomplete
Route statementFinite variation results retain selected polygon and spectral risk

Finite hull-area or stated mixed variation yields source-reported sufficient results only through the selected simple-polygon and spectral-import hypotheses. The sharp half-Hölder primitive threshold is not a sharp square-existence threshold. Infinite local unsigned hull variation does not supply signed charge, smooth models, primitive failure or actual crossings.

Source-reported route statement · dependencies incomplete
Route statementActual positive response remains an additional premise

Positive all-secants endpoint variation or positive response to a bounded smooth Hamiltonian can force a square under the displayed imports and source interfaces. Full-gradient, common-gauge and actual-detection hypotheses remain explicit. Abstract flat models do not establish realization by a Jordan curve; weak averaging can destroy nonlinear single-square moment equality; positive spectral response and bounded strain are additional inputs.

Source-reported route statement · dependencies incomplete

More ways to contribute

Open questions

Additional prepared tasks for exploring this research frontier.

33 featured tasks
01
B45-S

Reconstruct each smooth spectral, polygon-simplicity and marked-source import at its exact scope; do not treat project strain formulas as external theorems or QSI implementation.

Suggested move: Reconstruct each smooth spectral, polygon-simplicity and marked-source import at its exact scope; do not treat project strain formulas as external theorems or QSI implementation.
Ready to work on
02
B51-C/R51-C

Exclude simultaneous collapse on the same all-scale continuum in every relative-scale and chord-parameter regime; a normalized square does not complete fourth contact.

Suggested move: Exclude simultaneous collapse on the same all-scale continuum in every relative-scale and chord-parameter regime; a normalized square does not complete fourth contact.
Ready to work on
03
B43-D/R43-D

Retain first detection across switches and prevent collapse without equating grading and action cost.

Suggested move: Retain first detection across switches and prevent collapse without equating grading and action cost.
Ready to work on
04
B51-T/R51-T

Obtain global compatibility or the required approximation rate, rather than excluding one local cap picture.

Suggested move: Obtain global compatibility or the required approximation rate, rather than excluding one local cap picture.
Ready to work on
05
B43-A/R43-A

Force variation for the actual product-geometric detector, beyond the axioms defeated by flat models.

Suggested move: Force variation for the actual product-geometric detector, beyond the axioms defeated by flat models.
Ready to work on
06
B45-H/R45-H

Force positive bounded-probe response or controlled endpoint variation; individual moments and unbounded Hessians are insufficient.

Suggested move: Force positive bounded-probe response or controlled endpoint variation; individual moments and unbounded Hessians are insufficient.
Ready to work on
07
B43-Q/R43-Q

Implement all listed QSI conditions in the actual category, rather than substituting an abstract lemma.

Suggested move: Implement all listed QSI conditions in the actual category, rather than substituting an abstract lemma.
Ready to work on
08
B37-F/R37-F

Construct a positive-wall/pair-space family map with every named source, seam, action-rim, frame and selection face.

Suggested move: Construct a positive-wall/pair-space family map with every named source, seam, action-rim, frame and selection face.
Ready to work on
09
B51-R/R51-R

Use a nonzero return degree without extracting a path; deal with narrow return and the all-zero-degree positive-order case.

Suggested move: Use a nonzero return degree without extracting a path; deal with narrow return and the all-zero-degree positive-order case.
Ready to work on
10
B39-K

Terminate cofinal exact-critical charged states at their actual scope or construct a coherent family; retain the alternative even without outer safety.

Suggested move: Terminate cofinal exact-critical charged states at their actual scope or construct a coherent family; retain the alternative even without outer safety.
Ready to work on
11
B41-V/R41-V

Supply full-tail circumcircle variation or physical cap uniform integrability on one charged spine, or contradict its concentration.

Suggested move: Supply full-tail circumcircle variation or physical cap uniform integrability on one charged spine, or contradict its concentration.
Ready to work on
12
B47-H/R47-H

Use the remaining infinite local hull-variation alternative without converting unsigned accumulation into signed charge or crossings.

Suggested move: Use the remaining infinite local hull-variation alternative without converting unsigned accumulation into signed charge or crossings.
Ready to work on
13
B37-SRC/R37-E

Independently reconstruct the marked QSL-1C statement and risk scope.

Suggested move: Independently reconstruct the marked QSL-1C statement and risk scope.
Ready to work on
14
B45-G/R45-G

Replace the false universal budget task by a square-free-conditional or explicitly restricted construction with the actual stated cost.

Suggested move: Replace the false universal budget task by a square-free-conditional or explicitly restricted construction with the actual stated cost.
Ready to work on
15
B0/B1: retain controlled-sector contour-shell mass and accumulate its defects into a valid relation or excluded model.Suggested move: B0/B1: retain controlled-sector contour-shell mass and accumulate its defects into a valid relation or excluded model.
Ready to work on
16
B2a: select a proper oriented elegant carrier or classify every singular continuation obstruction.Suggested move: B2a: select a proper oriented elegant carrier or classify every singular continuation obstruction.
Ready to work on
17
B4S: convert hidden/cancellation defects or localized target data into a source-sheet, grid, packet-chain, or stressed-slab theorem.Suggested move: B4S: convert hidden/cancellation defects or localized target data into a source-sheet, grid, packet-chain, or stressed-slab theorem.
Ready to work on
18
B4T: classify every compactness failure by a proved transition or escape coordinate.Suggested move: B4T: classify every compactness failure by a proved transition or escape coordinate.
Ready to work on
19
B6: independently formalize every P* input actually used by a terminal route and audit orientations and compactification faces.Suggested move: B6: independently formalize every P* input actually used by a terminal route and audit orientations and compactification faces.
Ready to work on
20
RC-21: construct the finite-slab base-times-target three-current, cap/slicing formula, anchor transport, and every boundary face.Suggested move: RC-21: construct the finite-slab base-times-target three-current, cap/slicing formula, anchor transport, and every boundary face.
Ready to work on
21
B47-E/R47-E

Bridge actual three-contact continua to four crossings or a terminal model; third contact itself is no longer the missing task.

Suggested move: Bridge actual three-contact continua to four crossings or a terminal model; third contact itself is no longer the missing task.
Ready to work on
22
B41-E

Bound unweighted energy on one contiguous CAS band or terminate concentration; sigma-weighted estimates alone do not suffice.

Suggested move: Bound unweighted energy on one contiguous CAS band or terminate concentration; sigma-weighted estimates alone do not suffice.
Ready to work on
23
B45-P/R45-P

Extract an actual applicable geometric model or finite certificate from the curve; none follows from embeddedness alone.

Suggested move: Extract an actual applicable geometric model or finite certificate from the curve; none follows from embeddedness alone.
Ready to work on
24
B49-C/R49-C

Use actual connections, whole matching or closed collar traversal; strand count and a pencil limit do not suffice.

Suggested move: Use actual connections, whole matching or closed collar traversal; strand count and a pencil limit do not suffice.
Ready to work on
25
B37-C/R37-D

Retain aligned and crossed endpoint channels and distinguish tangent-singular from charged pairs.

Suggested move: Retain aligned and crossed endpoint channels and distinguish tangent-singular from charged pairs.
Ready to work on
26
COV-1

Prove that actual sufficient endpoints cover every remaining Jordan curve; completing one conditional subbranch does not close the target.

Suggested move: Prove that actual sufficient endpoints cover every remaining Jordan curve; completing one conditional subbranch does not close the target.
Ready to work on
27
R37-G/B37-G

Prove all-Jordan coverage for any independent Floer/rhombus route and any claimed class/action comparison.

Suggested move: Prove all-Jordan coverage for any independent Floer/rhombus route and any claimed class/action comparison.
Ready to work on
28
B37-A/R37-A

Convert near-singular occupation into oriented geometry with actual lifts, labels and excursions.

Suggested move: Convert near-singular occupation into oriented geometry with actual lifts, labels and excursions.
Ready to work on
29
B37-D/R37-C

Terminate the same persistent charged gap, including unbounded normalized lens mass, without converting normalized limits into physical control.

Suggested move: Terminate the same persistent charged gap, including unbounded normalized lens mass, without converting normalized limits into physical control.
Ready to work on
30
B49-M/R49-M

Retain every source boundary of the actual rough missing-vertex incidence, including an indispensable zero-action connector.

Suggested move: Retain every source boundary of the actual rough missing-vertex incidence, including an indispensable zero-action connector.
Ready to work on
31
B37-E

Obtain coherent tangent, germ and sign information on the same gap despite low-speed backtracking.

Suggested move: Obtain coherent tangent, germ and sign information on the same gap despite low-speed backtracking.
Ready to work on
32
B37-B/R37-B

Recover source, tangent and radial data and selected faces; finite analytic complexity is not uniform mass.

Suggested move: Recover source, tangent and radial data and selected faces; finite analytic complexity is not uniform mass.
Ready to work on
33
B3: convert an isolated later vertex-on-side incidence or endpoint relation into an inscribed boundary square, or into a route already covered by B2b, B4S, or B4T.Suggested move: B3: convert an isolated later vertex-on-side incidence or endpoint relation into an inscribed boundary square, or into a route already covered by B2b, B4S, or B4T.
Ready to work on

Sourced mathematical context

The known mathematical landscape

Context collected Aug 21, 2026
Current statusOpen problem

Recent Floer-theoretic work proves rectangle and square results under substantial regularity or geometric hypotheses; the full arbitrary-Jordan-curve problem remains open.

[1][2]
External progress

What the literature has established

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

  1. PreprintFloer homology and square pegs supplies a representative external result or boundary relevant to the problem; it is not treated here as a proof of the full packet target.[1]
  2. PreprintThe rectifiable rectangular peg problem supplies a representative external result or boundary relevant to the problem; it is not treated here as a proof of the full packet target.[2]
2 cited sources1 related results or reductionsReferences

Mathematical neighborhood

Related results and reusable starting points

Current focusInscribed Square Problem
Related problemInscribed Square Problem

Recent Floer-theoretic work proves rectangle and square results under substantial regularity or geometric hypotheses; the full arbitrary-Jordan-curve problem remains open.

[1][2]

Formalization opportunities

Lean work can make these reusable foundations precise without being presented as a proof of the core problem.

  • Formalization targetA formal statement matching the exact public target and all quantifiers.
  • Formalization targetFormal libraries for the principal mathematical structures used by the strongest route.
  • Formalization targetA checked closing argument for the source-identified open bridge.

Later mathematical changes

What changed after the initial research map

Later recorded revisions that changed the mathematics, without inventing a date or an AI attribution.

Retain the v52 boundary-continuum, inherited and detector frontiers with corrected recurrence/budget scope, distinct open tasks and inactive predecessors; the all-Jordan square target remains open.Retain the v52 boundary-continuum, inherited and detector frontiers with corrected recurrence/budget scope, distinct open tasks and inactive predecessors; the all-Jordan square target remains open.

Changed the research frontierLater mathematical revision

Private recorded successor preparation; no public priority claim
v20 repairs and narrows the four-engine Inscribed Square frontierThe cumulative v20 source reports quantitative analytic and finite-dimensional advances while preserving the exact open target and naming the unresolved carrier, transfer, localization, transition, and formal interfaces.

Changed the research frontierLater mathematical revision

Cumulative v20 source ingested; not a claim of mathematical occurrence time

The initial argument structure appears separately. Uploads, model runs, and presentation changes do not count as mathematical updates.

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.

Research-record correctionWe corrected supporting details in the research record. The mathematical claims and their status did not change.

Corrected the research recordCorrection note

Correction details
Research-record correctionWe corrected the cited passages. We updated the highlighted open task or route. The mathematical claims and their status did not change.

Corrected the research recordCorrection note

Correction details
Research-record correctionWe corrected the cited passages. We removed a duplicate or outdated task or route step. We updated the highlighted open task or route. The mathematical claims and their status did not change.

Corrected the research recordCorrection note

Correction details
Research-record correctionWe corrected the cited passages. We removed a duplicate or outdated task or route step. We updated the highlighted open task or route. The mathematical claims and their status did not change.

Corrected the research recordCorrection note

Correction details
Research-record correctionWe removed a duplicate or outdated task or route step. The mathematical claims and their status did not change.

Corrected the research recordCorrection note

Claim connections clarified

The initial argument structure appears separately. Uploads, model runs, and presentation changes do not count as mathematical updates.

Detailed research inventory

Claims, milestones, and routes in the current map

This inventory covers all currently cataloged mathematical statements in the research notes.

20 standing statements3 proposed statements33 open questions
Statements by mathematical role23 mapped statements
  • equivalence1 of 231
  • lemma16 of 2316
  • negative result1 of 231
  • reduction4 of 234
  • theorem candidate1 of 231
Complete mathematical inventory1 mathematical clusters
v52 recorded research frontierThe current frontier is global exclusion of BMC-1/B4P-1 coupled total collision. Third-contact reconstruction is no longer the missing task; an approximate-map path does not yield an exact three-contact path. Both return-degree cases, source orientations and relative-scale alternatives remain, and inherited routes retain their original hypotheses and source risks. The current work reports conditional arguments, imports, scoped obstructions and limited checks without a complete proof or formal certification.81 displayed rows · 9 routes included
  • retained route statementSquare-free contradiction formulationintermediate
  • retained route statementAN-22--AN-29 quantitative corridor and target-current packetintermediate
  • retained route statementv20 implication firewall and retired shortcutsintermediate
  • retained route statementRadial/capping carrier and typed-transfer engineintermediate
  • retained route statementSource-localized self-stress/model engineintermediate
  • retained route statementElegant contour-shell engineintermediate
  • Useful failureRepresentation-level, regularity, and calibrated-moment shortcutsreported failure
  • Research targetB2a: select a proper oriented elegant carrier or classify every singular continuation obstruction.open
  • Research targetRC-21: construct the finite-slab base-times-target three-current, cap/slicing formula, anchor transport, and every boundary face.open
  • Research targetB3: convert an isolated later vertex-on-side incidence or endpoint relation into an inscribed boundary square, or into a route already covered by B2b, B4S, or B4T.open
  • Research targetB4S: convert hidden/cancellation defects or localized target data into a source-sheet, grid, packet-chain, or stressed-slab theorem.open
  • Research targetB0/B1: retain controlled-sector contour-shell mass and accumulate its defects into a valid relation or excluded model.open
  • Research targetB4T: classify every compactness failure by a proved transition or escape coordinate.open
  • Research targetB6: independently formalize every P* input actually used by a terminal route and audit orientations and compactification faces.open
  • retained route statementEvery planar Jordan curve contains a nondegenerate square
  • retained route statementParallel boundary, fixed-action and detector routesintermediate
  • retained route statementClose every remaining Jordan-curve alternativeintermediate
  • retained route statementSeparate unmarked QSI and marked source riskintermediate
  • retained route statementFixed action without a chosen square selectorintermediate
  • retained route statementStopping deficits and phase costs retain their quantifiersintermediate
  • retained route statementRetain source faces, both endpoint channels and physical scaleintermediate
  • retained route statementA terminal on one complete regular charged leafintermediate
  • retained route statementGeometric subclasses and finite certificate scopeintermediate
  • retained route statementRecurrence needs positive size and actual connectionsintermediate
  • retained route statementOne connected all-scale three-contact continuumintermediate
  • retained route statementSource order, return degree and positive capsintermediate
  • retained route statementCoupling removes decreasing size, not total collapseintermediate
  • retained route statementLocal countermodels do not realize a square-free Jordan carrierintermediate
  • retained route statementThe universal ambient budget is withdrawnintermediate
  • retained route statementFinite variation results retain selected polygon and spectral riskintermediate
  • retained route statementActual positive response remains an additional premiseintermediate
  • Recorded relationshipThe displayed boundary, fixed-action and detector routes support a conditional approach to the all-Jordan endpoint only together with an exhaustion theorem covering every remaining curve. The source explicitly leaves COV-1 and each named terminal open; this edge is a proposed sufficiency relation, not a derivation of the target.supports · reported by source
  • Recorded relationshipRetain the earlier all-deep-family premise only inside the inherited fixed-action branch. The v52 frontier keeps full-tail family and formal comparison hypotheses; that retained premise supplies neither the independent boundary-continuum terminal nor an actual detector implementation.supports · reported by source
  • Recorded relationshipThe earlier odd relative radial class and conditional carrier-end cocycle remain bounded by their retained predecessor-source carrier, cap/slicing, anchor and full-boundary conditions. The current source material separately defines labelled cap/current boundaries, retains every named face, and refuses to identify its new boundary integers with integrated cap currents or action without a named comparison. This edge records that current limitation; it does not claim that the new continuum constructs the historical carrier or RC-21.supports · reported by source
  • Recorded relationshipThe earlier finite-dimensional self-stress data and model exclusions retain their predecessor-source scope. The current source material derives filled-rectangle response and spatial-strain estimates for the displayed smooth spectral setting, with compulsory positive endpoint displacement as an extra hypothesis. These response formulas supply neither the historical source-localized packet-chain propagation nor full-target exhaustion; no equivalence between the two stress notions is asserted.supports · reported by source
  • Recorded relationshipThe earlier lossless lowering measure and contour-shell context retain their predecessor-source controlled-sector and defect-accumulation conditions. The current source material has shifted-radius transport estimates and a stopped first-hit graph, but explicitly withholds a full-tail L1 bound and uniform mass and retains hits, no-hits, fillers and restriction faces. This edge does not identify that graph with the historical shell current or infer a terminal transition from the shared notation.supports · reported by source
  • Recorded relationshipThe earlier recorded firewall remains retained at its predecessor scope. The current no-revisit registry independently requires the correct mark/action comparisons, actual carriers and jump excursions, both continuation alternatives and endpoint channels, and all current faces and physical cap hypotheses. Its finite identities, normalized limits and one-branch terminals do not close COV-1 or reinstate an earlier rejected implication.supports · reported by source
  • Recorded relationshipAt the displayed charged-state scope, the signed-chain action estimate gives turning-cost lower bounds, not a contradiction. The stopping construction starts on one surviving radial square spine with a continuous charged action representative and retains the first critical-or-height alternative. These are conditional continuations of the fixed-action branch; they neither select an arbitrary all-Jordan family nor complete the target.supports · reported by source
  • Recorded relationshipThe inherited transport, cap and frontier interfaces start on the displayed CAS-1 sheet or charged spine and retain that family and every boundary face. The stopped two-sheet frontier over a contiguous action interval retains source/seam/action-rim/selection faces; its flat estimate is not a bound on boundary mass or a claim of singular support. These supplied-family statements depend on the fixed-action/stopping construction and do not provide an all-Jordan terminal.supports · reported by source
  • Recorded relationshipOn one coherent regular charged family, the circumcircle formulas yield the stated terminal only with full-tail physical cap uniform integrability or absolute weighted center/radius variation. Pointwise bounded energy, cofinal compactness, relabeling or normalized cap convergence do not supply that premise. This is a conditional terminal of the retained charged-family route, not a proof for every Jordan curve.supports · reported by source
  • Recorded relationshipOn the source-ordered exact continuum K, the conserved cap indices give the displayed return-degree formula. A nonzero degree permits compact connected-base continuation to an exact return family; reverse order forces such a degree, while positive order may have all degrees zero. A return point is not the missing corner, and the endpoint return is terminal only with positive limiting side. This conditional chain does not identify cap winding with action or construct a path through K.supports · reported by source
  • Recorded relationshipThe second missing-corner coupling and the connected size-floor construction yield BMC-1 for every sufficiently small prescribed side on the same all-scale continuum, independently of a nonzero return degree. B4P-1 then supplies four separated actual boundary points. They need not be the corners of one square, and simultaneous physical collapse remains possible; the source supplies neither a compatible path across scales nor a terminal for every relative-size/chord-parameter regime.supports · reported by source
  • DerivationThe governing source separates partial or conditional routes from exhaustive target closure. The conjecture would require every displayed premise and every remaining branch to be discharged. This is an informal dependency record, not a verified derivation.proposed
  • Research targetB51-C/R51-Copen
  • Research targetB51-R/R51-Ropen
  • Research targetB51-T/R51-Topen
  • Research targetB45-P/R45-Popen
  • Research targetB47-E/R47-Eopen
  • Research targetB49-C/R49-Copen
  • Research targetB49-M/R49-Mopen
  • Research targetB45-G/R45-Gopen
  • Research targetB47-H/R47-Hopen
  • Research targetB45-H/R45-Hopen
  • Research targetB45-Sopen
  • Research targetB43-Q/R43-Qopen
  • Research targetB37-SRC/R37-Eopen
  • Research targetB43-A/R43-Aopen
  • Research targetB43-D/R43-Dopen
  • Research targetR37-G/B37-Gopen
  • Research targetB41-V/R41-Vopen
  • Research targetB39-Kopen
  • Research targetB37-A/R37-Aopen
  • Research targetB37-C/R37-Dopen
  • Research targetB41-Eopen
  • Research targetB37-B/R37-Bopen
  • Research targetB37-D/R37-Copen
  • Research targetB37-Eopen
  • Research targetB37-F/R37-Fopen
  • Research targetCOV-1open
  • Useful failureRSE-2 / NR-437reported failure
  • Useful failureUAP-1 / B45-G/R45-G / AGC-1 / AGC-2reported failure
  • Useful failureAFC-1 / MOM-1reported failure
  • Active routeRetained v20 route: Two-center analytic corridorThe retained v20 source reports this route and its unresolved interfaces. Its mathematical statement remains historical recorded evidence; the v52 update does not infer completion from omission. Source-reported live engine with explicit unresolved interfaces; it is not a completed route to the conjecture.
  • Active routeRetained v20 route: Radial alternating end transferThe retained v20 source reports this route and its unresolved interfaces. Its mathematical statement remains historical recorded evidence; the v52 update does not infer completion from omission. Source-reported live engine with explicit unresolved interfaces; it is not a completed route to the conjecture.
  • Active routeRetained v20 route: Two-center self-stress/model routeThe retained v20 source reports this route and its unresolved interfaces. Its mathematical statement remains historical recorded evidence; the v52 update does not infer completion from omission. Source-reported live engine with explicit unresolved interfaces; it is not a completed route to the conjecture.
  • Active routeRetained v20 route: Elegant contour-shell routeThe retained v20 source reports this route and its unresolved interfaces. Its mathematical statement remains historical recorded evidence; the v52 update does not infer completion from omission. Source-reported live engine with explicit unresolved interfaces; it is not a completed route to the conjecture.
  • Active routeRetained v20 route: R-E continuous-lift bypassThe retained v20 source reports this route and its unresolved interfaces. Its mathematical statement remains historical recorded evidence; the v52 update does not infer completion from omission. Source-reported live engine with explicit unresolved interfaces; it is not a completed route to the conjecture.
  • Active routeThree-contact continuum and total collisionThe boundary route starts from square-freeness and HUG-WRAP, reaches an exact global three-contact continuum, and then has geometric, degree/return, size-coupling and cap-approximation branches. Its live work is to exclude same-continuum total collision, handle the conditional return alternatives, or obtain global cap compatibility. All-zero return degrees and the distinct scale/chord-parameter regimes remain; no path, unnamed action comparison or complete all-Jordan terminal is supplied.
  • Active routeActual QSI and detector variationThe unmarked detector route requires actual QSI-1 implementation, including coherent natural maps and lifted/localized values, before its first natural image threshold and angular comparison can be used at the displayed finite-constructible scope. Marked QSL-1C/AI-RISK remains a separate unresolved source interface. Positive profile value or endpoint increase does not force positive square-angle slope, and abstract flat models do not settle actual geometric realization or preservation of first detection through switches.
  • Active routeRestricted primitive and positive-response routesThe primitive route uses the displayed common-support ambient budget or finite hull-area variation with selected simple polygons, retaining AI-CPL and AI-RISK; UAP-1 retires the unrestricted universal-budget construction while restricted or square-free-conditional constructions remain. The distinct smooth-response route uses its GL-SM-based formulas only with actual positive bounded-probe or controlled endpoint variation. Critical primitive regularity, unsigned hull accumulation, weak averages or a positive spectral value do not supply those missing inputs or full-target exhaustion.
  • Active routeComplete charged-family alternativesThe charged-family route retains both cofinal exact-critical states and one regular full-tail spine at the source's fixed-action scope. The regular branch keeps physical-cap variation or concentration, both stopping alternatives, complete frontier or coherent corridor, and bounded/unbounded energy and cap-product cases. Its circumcircle terminal needs actual full-tail absolute variation or physical cap uniform integrability on one coherent family. First-hit graph estimates, projected inverse concentration, kinematic examples or tangent concurrence do not supply all missing premises or COV-1.
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 bridgeReconstruct each smooth spectral, polygon-simplicity and marked-source import at its exact scope; do not treat project strain formulas as external theorems or QSI implementation.

The current research map records this as an open mathematical step.

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 the missing mathematical implication with all stated source hypotheses and retained boundary cases.
  • Retain exact evidence for an independent source-fidelity and mathematical review; a model, calculation or branch-only result does not complete the full target.

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Research contextPrepared context for any AI agent

Must every simple closed curve in the plane pass through the four corners of a square? The current research follows configurations with three corners on the curve and the fourth inside. It reports a connected family across all source separations and a coupling that prevents the second configuration from being smaller than the first. Both sizes can still collapse to zero. Conditional fixed-action, detector and regular-subclass methods remain separate routes, and none currently covers every Jordan curve.

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Sources and references2 cited works · next context review by Nov 21, 2026

The mathematical context was checked on Aug 21, 2026. Status can be refreshed sooner after a material result or claim.

  1. 1
    Floer homology and square pegspreprint · Joshua Evan Greene, Andrew Lobb · arXiv · 2024 · accessed Aug 21, 2026
  2. 2
    The rectifiable rectangular peg problempreprint · Tomohiro Asano, Yuichi Ike · arXiv · 2024 · accessed Aug 21, 2026

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  • This was a bounded status and identity check, not an exhaustive bibliography, priority review, or legal review.
  • Private packet claims were not treated as external authority; submitted links and attachments were not executed or actively rendered.
  • No absence claim is inferred from the bounded search, and recent preprints remain subject to ordinary scholarly review.

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