Linear bound on Betti numbers of negatively curved orbifolds.
problem Bounding Betti numbers of negatively curved orbifolds.
method Quantitative bound on the homology of spherical quotients.
result Linear growth of Betti numbers with volume, arbitrary field coefficients.
We show that asymptotically the first Betti number, or the arithmetic genus, of a Shimura curve satisfies the Gauss--Bonnet equality. We also show that the first Betti number of a congruence hyperbolic 3--orbifold asymptotically vanishes relatively to hyperbolic volume.
The paper uses Betti curves to confirm hyperbolic geometry in brain, climate, and financial networks.
problem Confirming the curvature of real-world networks using topology.
method Using Betti curves and integral Betti signatures derived from Persistent Homology to distinguish different geometric matrices.
result Integral Betti signatures effectively distinguish Euclidean, spherical, and hyperbolic geometric matrices.
In [DJL07] it was shown that if A is an affine hyperplane arrangement in C^n, then at most one of the L^2-Betti numbers of its complement is non--zero. We will prove an analogous statement for complements of any algebraic curve in C^2. Furthermore we also recast and extend results of [LM06] in terms of L^2-Betti number…
We prove that the second Betti number of a compact Riemannian manifold vanishes under certain Ricci curved restriction.
Study bounds index of minimal hypersurfaces in curved spaces.
problem Bounding the index of minimal hypersurfaces.
method Proved linear index bound using first Betti number and curvature.
result Index is bounded below by a linear function of first Betti number.
Moduli spaces of real bundles over a real curve arise naturally as Lagrangian submanifolds of the moduli space of semi-stable bundles over a complex curve. In this paper, we adapt the methods of Atiyah-Bott's "Yang-Mills over a Riemann Surface" to compute Z/2-Betti numbers of these spaces, proving formulas recently obt…
Study topological invariants of complexes for Riemannian manifolds.
problem Understanding topological properties of Riemannian manifolds.
method Analyzing Betti numbers and Euler characteristic of Vietoris-Rips and Čech complexes.
result Betti curve converges to manifold's Betti number within a scale parameter interval.
The paper proves a gap theorem for almost non-negatively curved manifolds.
problem Proving a gap theorem for almost non-negatively curved manifolds.
method Two novel technical tools: controlling the spreading of minimal geodesics and Ricci flow smoothing.
result Closed manifolds with bounded geometry are diffeomorphic to torus bundles.
We study the convergence of volume-normalized Betti numbers in Benjamini-Schramm convergent sequences of non-positively curved manifolds with finite volume. In particular, we show that if X is an irreducible symmetric space of noncompact type, X=H3, and (Mn) is any Benjamini-Schramm convergent sequ…
Improved lower bound for geodesics on manifolds.
problem Finding a lower bound for the number of minimal geodesics on Riemannian manifolds.
method Refined Bangert's method using the stable norm unit ball on the first homology.
result Quadratic lower bound for the number of minimal geodesics.
The study counts closed elliptic curves and Reeb orbits on Vaisman and Sasakian manifolds.
problem Counting closed orbits and elliptic curves on Vaisman and Sasakian manifolds.
method Analyzes the structure of Vaisman and Sasakian manifolds, uses quasi-regular and S1-quotients, and counts closed orbits and curves. result The number of closed elliptic curves and Reeb orbits is either infinite or equal to the sum of all Betti numbers of a Kähler orbifold.
Method counts zeros of Betti map for elliptic surface sections.
problem Counting zeros of Betti map for elliptic surface sections.
method Differential-geometric approach using Kähler metrics.
result Explicit linear estimates of Betti map multiplicities.
We prove generic fibre of Painlevé moduli spaces are Weinstein handlebodies.
problem Understanding the generic fibre of Painlevé moduli spaces.
method Attach Weinstein handles to Stokes Legendrian.
result Generic fibre of Painlevé moduli spaces are Weinstein handlebodies.
The paper studies cyclic covers of rational surfaces and their Hodge structures.
problem Understanding the Hodge structures of cyclic covers of rational surfaces.
method Generalization of Esnault-Viehweg method to analyze monodromy actions.
result The monodromy action splits into direct sums for specific cyclic covers.
Zeta functions extended to nonorientable surfaces, order of vanishing computed.
problem Computing dynamical zeta functions for nonorientable surfaces.
method Simple argument extending microlocal proofs to nonorientable case.
result Order of vanishing of zeta function is the first Betti number.
Complex manifolds can only map to curves, restricting Clemens threefolds and S6.
problem Restricting the mapping properties of complex manifolds and threefolds.
method Analyzing the properties of complex manifolds and their mappings.
result No holomorphic mapping from a specific class of threefolds onto a complex space.
The paper estimates Betti numbers for graphs with specific curvatures, proving bounds and characterizing rigidity.
problem Estimating Betti numbers for graphs with non-negative curvatures.
method Establishing Betti number estimates for graphs with non-negative Ollivier and Bakry-Émery curvatures.
result Upper bounds on the first Betti number for graphs with non-negative curvatures, with characterizations of rigidity.
By extending and generalising previous work by Ros and Savo, we describe a method to show that the Morse index of every closed minimal hypersurface on certain positively curved ambient manifolds is bounded from below by a linear function of its first Betti number. The technique is flexible enough to prove that such a r…
PHINN: A generative model for rare-event time series using persistent homology
problem Generating rare events in time series
method Flow-matching framework with dynamic Betti curves and persistence landscape loss
result Outperforms statistical and diffusion baselines in topological fidelity and tail coverage
Let X be an irreducible smooth geometrically integral projective surface over a field. In this paper we give an effective bound in terms of the Neron--Severi rank ρ(X) of X for the number of irreducible curves C on X with negative self-intersection and geometric genus less than b1(X)/4, where b1(X) is t…
We determine an explicit expression for the Ricci tensor of a K-manifold, that is of a compact Kaehler manifold M with vanishing first Betti number, on which a semisimple group G of biholomorphic isometries acts with an orbit of codimension one. We also prove that the Kaehler form and the Ricci form of M are uniquely d…
Let X be a finite CW-complex, denote its fundamental group by G. Let R be an n-dimensional complex repesentation of G. Any element A of the first cohomology group of X with complex coefficients gives rise to the exponential deformation of the representation R, which can be considered as a curve in the space of represen…
Upper bounds on Betti numbers via curvature constraints.
problem Bounding Betti numbers of Riemannian manifolds.
method Integral bounds on curvature eigenvalues, Bochner technique.
result New curvature condition for vanishing Betti numbers.
We prove that a closed arithmetic hyperbolic 3-manifold with positive first betti number has virtually infinite first betti number.
Study L^2-Betti numbers in prime characteristic for a conjecture about 2-complex towers.
problem Verify a conjecture about 2-complex towers using L^2-Betti numbers.
method Systematically study L^2-Betti numbers in zero and prime characteristic.
result Apply L^2-Betti numbers to verify a conjecture about 2-complex towers.
Research confirms a conjecture about complex manifolds with total Betti number three.
problem Understanding the minimal total Betti number of closed almost complex manifolds.
method Analyzing properties of almost complex manifolds and using topological results.
result The only simply connected closed complex manifold with total Betti number three is the complex projective plane.
Lower Ricci curvature bound prevents first Betti number from dropping more than dimension in collapsing manifolds.
problem Understanding how the first Betti number behaves under manifold collapse with Ricci curvature bounds.
method Analyzing sequences of Riemannian manifolds with lower Ricci curvature bounds.
result The first Betti number cannot drop more than the dimension in collapsing manifolds.
This paper has two main goals. First, we give a complete, explicit, and computable solution to the problem of when two simple closed curves on a surface are equivalent under the Johnson kernel. Second, we show that the Johnson filtration and the Johnson homomorphism can be defined intrinsically on subsurfaces and prove…
Flat open manifolds with full first Betti number have zero curvature.
problem Maximal first Betti number rigidity for open manifolds with nonnegative Ricci curvature.
method Proving rigidity for open manifolds with specific curvature conditions and Betti numbers.
result Open manifolds with maximal first Betti number are flat.
Estimates Betti numbers of loop spaces of compact manifolds.
problem Estimating Betti numbers of loop spaces of compact manifolds.
method Using finite Grauert tubes to provide an effective estimate.
result Implication of polynomial estimate in the limit of tube radius.
Study on lens spaces bounding 4-manifolds with specific Betti numbers.
problem Which lens spaces can bound 4-manifolds with second Betti number one?
method Construction of specific 4-manifolds and analysis of lens space boundaries.
result Infinite families of lens spaces can bound 4-manifolds with second Betti number one, but not all.
Twists agrarian and ℓ2-Betti numbers for locally indicable groups.
problem Understanding ℓ2-Betti numbers of locally indicable groups. method Using generalised agrarian invariants and twisted Alexander-Thurston norms.
result Twisted ℓ2-Betti numbers are equal to usual ℓ2-Betti numbers rescaled by the dimension of the twisting representation. The paper calculates Betti numbers for special geometric manifolds with curvature constraints.
problem Estimating Betti numbers for nearly G2 and nearly Kähler manifolds with curvature bounds. method Using Weitzenböck formulas and bounds on sectional curvature to estimate Betti numbers.
result Sufficient conditions for vanishing certain Betti numbers based on sectional curvature bounds.
Found the smallest 4-manifold with a specific Betti number.
problem Finding a 4-manifold with a specific Betti number.
method Provided an explicit example of a cork for a 4-manifold.
result First explicit example of a cork with second Betti number 9.
The paper uses Tannakian reconstruction to understand hyperbolic log-orbi curves.
problem Understanding the structure of hyperbolic log-orbi curves.
method Formulates hyperbolic uniformization as a Tannakian reconstruction theorem and constructs a canonical maximal parahoric PSL2-Higgs object.
result Reconstructs the absolute Galois group of a one-variable complex function field as the inverse limit of etale fundamental groups of orbifold models.
If Γ is any nonuniform lattice in the group PU(2,1), let Γ be the quotient of Γ obtained by filling the cusps of Γ (i.e. killing the center of parabolic subgroups). Assuming that such a lattice Γ has positive first Betti number, we prove that for any sufficiently deep subgroup of finite index…
We propose an intuitive interpretation for nontrivial L2-Betti numbers of compact Riemann surfaces in terms of certain loops in embedded pairs of pants. This description uses twisted homology associated to the Hurewicz map of the surface, and it satisfies a sewing property with respect to a large class of pair-of-pa…
We provide a proof for an inequality between volume and L2-Betti numbers of aspherical manifolds for which Gromov outlined a strategy based on general ideas of Connes. The implementation of that strategy involves measured equivalence relations, Gaboriau's theory of L2-Betti numbers of R-simplicial complexes, and other …
The paper establishes a correspondence between Higgs torsors and connections on curves.
problem Establishing a correspondence between Higgs torsors and connections on curves.
method Introduced a stability condition on filtered Stokes local systems and used it to prove a one-to-one correspondence.
result One-to-one correspondence between stable meromorphic parahoric Higgs torsors and stable meromorphic parahoric connections.
The moduli space Δg,w of tropical w-weighted stable curves of volume 1 is naturally identified with the dual complex of the divisor of singular curves in Hassett's spaces of w-weighted stable curves. If at least two of the weights are 1, we prove that Δ0,w is homotopic to a wedge sum of spheres, possi…
In this paper we state and prove Morse type inequalities for Morse functions as well as for closed differential 1-forms. These inequalities involve delocalized Betti numbers. As an immediate consequence, we prove the vanishing of delocalized Betti numbers of manifolds fibering over the circle.
The study finds large Betti numbers in minimal hypersurfaces with positive Ricci curvature.
problem Minimal hypersurfaces with large Betti numbers in manifolds with positive Ricci curvature.
method Constructing sequences of manifolds with embedded minimal hypersurfaces.
result Minimal hypersurfaces have unbounded first Betti numbers.
Study Bochner formula on metric measure spaces for vanishing Betti numbers.
problem Vanishing Betti numbers on metric measure spaces.
method Introduce weighted curvature conditions.
result Vanishing of all Betti numbers.
Study estimates index of minimal hypersurfaces using Betti numbers.
problem Estimating the index of unstable minimal hypersurfaces.
method Extends previous method using first Betti number.
result Morse index is bounded by first Betti number.
Study computability of real numbers from group properties.
problem Computability of real numbers from group properties.
method Analyzing L2-Betti numbers and L2-torsion of groups. result Real numbers as L2-Betti numbers or L2-torsion are computable. Study rigidifies torus bundles under first Betti number constraints.
problem Understanding the structure of torus fibrations under first Betti number restrictions.
method Established rigidity results and necessary/sufficient conditions for topological splitting.
result Classification of torus bundles under specific Betti number constraints.
Suppose X is any finite complex with vanishing L^2 Betti number. We prove upper bounds on the Betti numbers for regular coverings of X, sublinear in the order of covering. The bounds are sensitive to the Novikov-Shubin invariants of X, and are improved in the presence of a spectral gap.