arXiv research

The paper shows how to unknot certain nonorientable surfaces in 4-dimensional spaces.

Let $M$ be a compact 3-manifold with a triangulation $τ$. We give an inequality relating the Euler characteristic of a surface $F$ normally embedded in $M$ with the number of normal quadrilaterals in $F$. This gives a relation between a topological invariant of the surface and a quantity derived from its combinatorial …

The study bounds the excess of disjoint nonorientable surfaces in a 4-manifold.

Researchers refine the non-orientable $4$-genus of torus knots using Batson's surfaces.

The group of bordism classes of unoriented surfaces in 4-space is determined. The bordism classes are characterized by normal Euler numbers,double linking numbers, and triple linking numbers.

We prove that the difference between the numbers of positive swallowtails and negative swallowtails of the Blaschke normal map for a given convex surface in affine space is equal to the Euler number of the subset where the affine shape operator has negative determinant.

New methods find minimal crossing numbers for surfaces in $S^4$.

Counted essential surfaces in a knot's exterior, finding a unique pattern.

A formula that relates triple points, branch points, and their distances from infinity is presented. We recover trivial normal Euler classes for oriented surfaces, and formulas on signed triple points.

Shows Euler-like vector fields come from specific embeddings.

We found a unique 4D plane that can't be simplified.

In this paper, we study the (normalized) Ricci flow on surfaces with conical singularities. Long time existence is proved for cone angle smaller than $2π$. In this case, convergence results are obtained if the Euler number is nonpositive.

A natural oriented (2k+2)-chain in CP^{2k+1} with boundary twice RP^{2k+1}, its complex shade, is constructed. Via intersection numbers with the shade, a new invariant, the shade number of k-dimensional subvarieties with normal vector fields along their real part, is introduced. For an even-dimensional real variety, th…

The paper derives new Gauss-Bonnet formulas for frontal bundles over surfaces with boundary.

Following Matveev, a k-normal surface in a triangulated 3-manifold is a generalization of both normal and (octagonal) almost normal surfaces. Using spines, complexity, and Turaev-Viro invariants of 3-manifolds, we prove the following results: 1) a minimal triangulation of a closed irreducible or a bounded hyperbolic 3-…

Paper proposes efficient method to calculate Fisher-Bingham distribution normalizing constant.

Trisections are obtained by regluing surface-knots in 4-manifolds.

Counting essential surfaces in 3-manifolds yields concise formulae and detailed asymptotics.

We find formal and holomorphic normal forms for a class of meromorphic connections (the so-called $(TE)$-structures) over the irreducible $2$-dimensional globally nilpotent $F$-manifold germ $\mathcal N_{2}$. We find normal forms for Euler fields on $\mathcal N_{2}$ and we characterize the Euler fields on $\mathcal N_{…

Germs of tubular neighborhood embeddings for submanifolds N of manifolds M are in one-one correspondence with germs of Euler-like vector fields near N. In many contexts, this reduces the proof of `normal forms results' for geometric structures to the construction of an Euler-like vector field compatible with the given …

Bridge trisections and knotted surfaces connected via tri-plane diagrams.

Extends Euler class result to symplectic group.

We study the interplay among Wall's $D(2)$ problem, normal generation conjecture (the Wiegold Conjecture) of perfect groups and Swan's problem on partial Euler characteristic and deficiency of groups. In particular, for a 3-dimensional complex $X$ of cohomological dimension 2 with a finite fundamental group, assuming t…

The paper defines and studies new types of submanifolds in a unit sphere.

The paper derives a local formula for the Euler number of circle bundles.

Given a triangulation of a closed, oriented, irreducible, atoroidal 3-manifold every oriented, incompressible surface may be isotoped into normal position relative to the triangulation. Such a normal oriented surface is then encoded by non-negative integer weights, 14 for each 3-simplex, that describe how many copies o…

A rational linear combination of Chern numbers is an oriented diffeomorphism invariant of smooth complex projective varieties if and only if it is a linear combination of the Euler and Pontryagin numbers. In dimension at least three only multiples of the top Chern number, which is the Euler characteristic, are invarian…

Study the topological information of map germs using Euler obstruction.

In this paper, we apply classical energy principles to Euler elasticae, i.e., closed C^2 curves in the plane supplied with the Euler functional U (the integral of the square of the curvature along the curve). We study the critical points of U, find the shapes of the curves corresponding to these critical points and sho…

We define a "circle Euler characteristic" of a circle action on a compact manifold or finite complex X. It lies in the first Hochschild homology group of ZG where G is the fundamental group of X. It is analogous in many ways to the ordinary Euler characteristic. One application is an intuitively satisfying formula for …

Formula for Euler characteristic of moduli spaces of Abelian differentials.

Algorithm computes Thurston norm for hyperbolic 3-manifolds.

We prove that the mean Euler characteristic of a Gorenstein toric contact manifold, i.e. a good toric contact manifold with zero first Chern class, is equal to half the normalized volume of the corresponding toric diagram and give some applications. A particularly interesting one, obtained using a result of Batyrev and…

Using the equivalence between the renormalized Euler characteristic of Ozsvath and Szabo, and the Turaev torsion normalized by the Casson-Walker invariant, we make calculations for $S^3_{p/q}(K)$. An alternative proof of a theorem by Ozsváth and Szabó on $L$-space surgery obstructions is provided.

This paper studies symplectic structures on elliptic surfaces with positive Euler number.

The first purpose of this note is to comment on a recent article of Bursztyn, Lima and Meinrenken, in which it is proved that if M is a smooth submanifold of a manifold V, then there is a bijection between germs of tubular neighborhoods of M and germs of "Euler-like" vector fields on V. We shall explain how to approach…

In this paper, we use a result of Dahmani to show that the Euler class of some power subgroup (the subgroup normally generated by a fixed power of Dehn twist about a non-separating curve) is trivial inside the mapping class group of once punctured surface.

New algorithms compute crosscap numbers of knots and 3-manifolds.

Efficient triangulations help in understanding 3-manifold boundaries.

Optical interpretation of Euler's angle problem for caustics of light rays.

The Euler number of special symplectic hyperbolic manifolds is positive.

The paper investigates the relationship between curvature operator and Euler number on manifolds.

We study a normalized version of the second order renormalization group flow on closed Riemannian surfaces. We discuss some general properties of this flow and establish several basic formulas. In particular, we focus on surfaces with zero and positive Euler characteristic.

The study identifies unique fluid flow patterns.

Everyone knows that the Euler characteristic of a combinatorial manifold is given by the alternating sum of its numbers of simplices. It is shown that there are other linear combinations of the numbers of simplices which are combinatorial invariants, but that all such invariants are multiples of the Euler characteristi…

SGD converges to critical points of normalized margin in late-stage training for homogeneous neural networks.

We generalize Llarull's scalar curvature comparison to Riemannian manifolds admitting metric connections with parallel and alternating torsion and having a nonnegative curvature operator on 2-vectors. As a byproduct, we show that Euler number and signature of such manifolds are determined by their global holonomy repre…

Researchers found two types of graphs for 6D torus manifolds with Euler number 6.