Perelman's proof confirmed, new method uses 4D topology.
problem Confirming the classical Poincaré conjecture.
method 4D topology, spun torus-knots, ribbonness, disk-chord system, Bing's result.
result Homotopy 3-sphere is diffeomorphic to the 3-sphere.
Minimal hypertori found in 4D sphere, solving Bernstein conjecture.
problem Finding minimal embedded hypertori in 4D sphere.
method Analyzing minimally embedded and immersed hypertori and hyperspheres.
result Infinitely many non-isometric minimally embedded hypertori and hyperspheres found.
Low entropy hypersurfaces in 4D are isotopic to a sphere.
problem Characterizing hypersurfaces with low entropy in 4D.
method Proving isotopy to the standard 3-sphere for hypersurfaces with entropy ≤ cylinder entropy.
result Closed hypersurfaces with low entropy are isotopic to the standard 3-sphere.
Sharp inequality proven for symmetric functions on a 4D sphere.
problem Proving a sharp Beckner's inequality for axially symmetric functions on S4. method Utilized pointwise properties of Gegenbauer polynomials.
result Sharp Beckner's inequality established for axially symmetric functions on S4. The paper offers new methods to determine if certain 3D links can be formed by intersecting spheres in 4D space.
problem Determining if a 3D link can be formed by intersecting spheres in 4D space.
method Using obstructions from multivariable signature, Blanchfield form, and generalised Seifert matrices.
result Provides lower bounds on the doubly slice genus of links.
New spheres can split a 4D link in ways not possible in 3D.
problem Exploring how splitting spheres behave in 4D space.
method Constructing specific 2-component surface-links in S4. result Found non-isotopic splitting spheres in S4∖Lm,n. Develops Llarull type theorems for 3D and 4D bands with spectral scalar curvature bounds.
problem Bounding scalar curvature and metric on 3D and 4D bands simultaneously.
method Warped μ-bubble method result Establishes Llarull type theorems for 3D and 4D bands with spectral scalar curvature bounds.
New 4-manifold examples show necessary conditions for 4D Light Bulb Theorem.
problem Necessary conditions for the 4D Light Bulb Theorem.
method Constructing 4-manifolds with specific dual properties.
result Examples show the necessity of square zero assumption.
Approaches 4D Schoenflies via pseudo-isotopy.
problem Smooth 4D Schoenflies conjecture.
method Pseudo-isotopy theory.
result Offers new approach to 4D Schoenflies.
New minimal hypersurfaces in 4D sphere found.
problem Constructing embedded minimal hypersurfaces in S4. method Equivariant min-max theory and suspended Hopf action.
result Infinitely many topological S1-bundles and Seifert fibered manifolds found. Paper finds new 3D shapes that can be inside a 4D space.
problem Finding new 3D shapes with specific properties.
method Examined arithmetic hyperbolic 3-manifolds and their homology.
result Discovered infinitely many 3D shapes that are rational homology spheres and can bound geometrically.
New method finds non-orientable knotted surfaces in 4D.
problem Reducibility of knotted surfaces in 4D.
method Elementary obstruction to reducibility.
result Construction of stably irreducible non-orientable surfaces.
Algorithm constructs Kirby diagrams for 4D open books.
problem Constructing Kirby diagrams for 4D open books.
method Algorithm using Heegaard diagrams of pages.
result Diffeomorphic open books constructed with different pages and monodromies.
New maps show some surfaces can't be sections of 4D spheres.
problem Finding sections for certain 4D sphere maps.
method Exhibited singular fibrations with high genus fibers.
result Some regular fibers cannot be sections.
New theory classifies knotted spheres in 4D space.
problem Classifying knotted punctured spheres in 4D space.
method Diagrammatic theory of welded graphs, Tube map extension, Milnor invariants.
result Complete link-homotopy classification of knotted punctured spheres.
Synthetic construction of Hopf fibration in 4D space.
problem Visualizing 4D objects in 3D space.
method Double orthogonal projection method to visualize 4D space.
result Direct synthetic construction of 3-sphere fibers from 2-sphere points.
Study Murasugi sum in 4D for knotted surfaces, defining arborescent surfaces.
problem Defining and understanding Murasugi sum in 4D for knotted surfaces.
method Introduced a 4D Murasugi sum to define arborescent knotted surfaces.
result Defined and studied arborescent knotted surfaces using 4D Murasugi sum.
We construct infinitely many smooth oriented 4-manifolds containing pairs of homotopic, smoothly embedded 2-spheres that are not topologically isotopic, but that are equivalent by an ambient diffeomorphism inducing the identity on homology. These examples show that Gabai's recent "Generalized" 4D Lightbulb Theorem does…
The study connects surface geometry in 5D to 4D projections and umbilic curvatures.
problem Understanding the geometry of surfaces in 5D space.
method Relating surfaces in 5D to surfaces in 4D via projections and normal sections, analyzing asymptotic directions and umbilic curvatures.
result Relations between asymptotic directions and umbilic curvatures in 5D surfaces and their counterparts in 4D projections.
Refines knot defect measurement in 3D and 4D.
problem Measuring how far knots are from being alternating.
method Extends spanning surface defect to 4-ball, making comparisons and proving formulas.
result Connected sum formula proven.
Paper proves existence of a CMC hypertorus in 4D sphere using numerical methods.
problem Proving the existence of a constant mean curvature (CMC) hypertorus in \(S^4\).
method Employed the round Taylor method with rational arithmetic and the Poincare-Miranda theorem.
result Existence of a constant mean curvature (CMC) hypertorus in \(S^4\).
The paper explores biconservative surfaces in a 4D sphere, finding a unique family of non-isometric surfaces.
problem Characterizing biconservative surfaces with a parallel normalized mean curvature vector field in a 4D sphere.
method Analyzes existence and uniqueness, derives local parametrization.
result A 2-parameter family of non-isometric biconservative surfaces in a 4D sphere.
Study the singularities of Gauss map components of surfaces in 4D.
problem Characterize singularities of Gauss map components of surfaces in R4. method Analyze the geometric properties and stability of singularities.
result Singularities of Gauss map components are generically stable and related to surface geometry and J-holomorphic curves. Study of 3-handle attachments in 4D manifolds using Kirby calculus.
problem Inclusion of 3-handles in Kirby diagrams for 4D manifolds.
method Developed moves to extend Kirby calculus, established homological criterion.
result Identified geometric basis of 3-handle attachments, proved uniqueness theorem.
Hypernom is a virtual reality game. The cells of a regular 4D polytope are radially projected to S^3, the sphere in 4D space, then stereographically projected to 3D space where they are viewed in the headset. The orientation of the headset is given by an element of the group SO(3), which is also a space that is double …
Kervaire's sphere-link is equivalent to a ribbon sphere-link, simplifying complex 2-complexes.
problem Understanding the structure of 2-complexes and their asphericity.
method Using Kervaire's sphere-link and ribbon sphere-link equivalence, analyzing the compact complement of ribbon disk-links.
result Every connected subcomplex of a contractible finite 2-complex is aspherical.
3D space without definite 4D counterpart found.
problem Finding 3-manifolds that don't bound definite 4-manifolds.
method Analysis of characteristic covectors in bimodular lattices.
result A rational homology 3-sphere that bounds no definite 4-manifold.
New method shows nonorientable surfaces in 4D are topologically unknotted.
problem Tackles isotopy classes of nonorientable surfaces in D4. method Calculations implemented in Sage to show ambient isotopy.
result Closed, nonorientable surfaces in S4 are topologically unknotted. Algorithm finds knot diagrams from exterior triangulations.
problem Finding knot diagrams from their exteriors.
method First practical algorithm for finding diagrams from triangulations of exteriors.
result First diagrams for 23 link exteriors with over 2,500 crossings.
Study on null-torsion holomorphic curves in 6-sphere, focusing on their second variation.
problem Characterize the second variation of area for null-torsion holomorphic curves in the round 6-sphere.
method Analyzing the spectrum of the Jacobi operator for compact null-torsion holomorphic curves.
result For g≤6, the multiplicity of the lowest eigenvalue λ1=−2 is exactly 4d. Study on black holes and photon surfaces in 4D spacetimes, proving uniqueness theorems.
problem Uniqueness of black hole and photon surfaces in 4D spacetimes.
method Potential theory approach, self-contained proofs for known and new cases.
result Proves new results for connected photon spheres and photon surfaces in the extremal case, and super-extremal case.
Symmetrizes 4d and 3d BPS quivers for Argyres-Douglas theories.
problem Understanding the relationship between 4d and 3d BPS quivers.
method Analyzes geometric backgrounds and uses skein modules to derive quiver partition functions.
result Proves isomorphism between 4d wall-crossing and unlinking of symmetric quivers.
We show that the smooth geometry of a hyperbolic 3-manifold emerges from a classical spin system defined on a 2d discrete lattice, and moreover show that the process of this "dimensional oxidation" is equivalent with the dimensional reduction of a supersymmetric gauge theory from 4d to 3d. More concretely, we propose a…
Minimal area of spun trefoil knot is found in 4D cubical space.
problem Finding the minimum area for a spun trefoil knot in 4D cubical space.
method Defined minimal area of cubical 2-knots, used isotopy to find minimum area for spun trefoil.
result Spun trefoil knot requires a specific minimal area in 4D cubical space.
New 1-parameter family of ovals identified in 4d Ricci flow classification.
problem Classifying κ-solutions in 4d Ricci flow. method Introducing conjectures and constructing new examples.
result Established canonical neighborhood theorem for 4d Ricci flow.
Paper connects hypersurfaces in 4D to surfaces in 3-sphere.
problem Understanding conformally flat hypersurfaces in 4D space forms.
method Characterizes conformal structures and relates to surfaces in 3-sphere.
result Relates 2-metrics in 3-sphere to surfaces giving rise to conformally flat hypersurfaces.
Study of 4D Ricci solitons with symmetry, finding precise geometric asymptotics.
problem Classifying 4D gradient steady Ricci solitons and understanding their geometric properties.
method Analysis of 4D gradient steady Ricci solitons with O(3)-symmetry under a weak curvature decay condition.
result Find precise geometric asymptotics similar to 3D compact κ-solutions.
Study 4D solitons with specific curvature properties, proving curvature bounds and classifying solutions.
problem Investigate 4D gradient solitons with specific curvature properties.
method Analyze 4D gradient steady and shrinking solitons with nonnegative or half nonnegative isotropic curvature.
result Prove 2-nonnegativity of Ricci curvature and bound the curvature tensor for ancient solutions.
Study on 4D PDEs with half-flat conformal structure leading to Monge-Ampere equations.
problem Characterizing second-order PDEs in 4D with specific conformal structures.
method Analysis of Monge-Ampere property and dispersionless Lax pairs.
result All known scalar second-order integrable dispersionless PDEs in 4D are of Monge-Ampere type.
We found a unique 4D plane that can't be simplified.
problem Finding an irreducible embedded projective plane in S4. method Constructing a specific geometric shape in 4D space.
result The constructed projective plane is irreducible.
Study classifies special 4D shapes with certain curvature.
problem Classifying specific types of 4D shapes.
method Classifying compact almost-Kähler four manifolds with nonnegative biorthogonal curvature.
result Classified compact almost-Kähler four manifolds with nonnegative biorthogonal curvature.
The paper studies Willmore surfaces in 4D conformal manifolds and finds the Clifford torus is strictly Willmore-stable.
problem Exploring the Willmore functional for surfaces in 4D conformal manifolds.
method Detailed calculation of first and second variations, derivation of Euler-Lagrange equation in a conformally invariant form.
result The Clifford torus in CP2 is strictly Willmore-stable, supporting a conjecture. 4D theorem for disks, generalizing previous work.
problem Properly embedded disks in 4-manifolds.
method Generalization of Gabai and Kosanovic-Teichner's work, new geometric interpretation of Dax invariant.
result Homotopic disks are smoothly isotopic under certain conditions.
A class of 3d N=2 supersymmetric gauge theories are constructed and shown to encode the simplicial geometries in 4-dimensions. The gauge theories are defined by applying the Dimofte-Gaiotto-Gukov construction in 3d/3d correspondence to certain graph complement 3-manifolds. Given a gauge theory in this class…
We consider compactification of type IIA supergravity on nearly Kaehler manifolds. These represent a simple class of SU(3) structure manifolds which includes S^6 and CP^3. We exhibit for the first time an explicit reduction ansatz in this context, obtaining an N=2 gauged supergravity in 4d with a single vector and hype…
We explore 4d Yang-Mills gauge theories (YM) living as boundary conditions of 5d gapped short/long-range entangled (SRE/LRE) topological states. Specifically, we explore 4d time-reversal symmetric pure YM of an SU(2) gauge group with a second-Chern-class topological term at θ=π (SU(2)θ=π YM), by turning on backg…
New surfaces generalize Dini surfaces in 4D.
problem None explicitly stated; focuses on surface generalization.
method Introducing a new family of surfaces in 4D.
result Generalized Dini surfaces exist in 4D.
New ribbon disks in 4D space, non-isotopic to each other.
problem Non-isotopic ribbon disks in 4D.
method Using corks to construct diffeomorphic ribbon disks.
result Non-isotopic ribbon disks constructed in 4D.