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We show that there are a finite number of possible pictures for a surface in a tetrahedron with local index $n$. Combined with previous results, this establishes that any topologically minimal surface can be transformed into one with a…

几何拓扑 · 数学 2013-03-28 David Bachman

A unimodular complex surface is a complex 2-manifold X endowed with a holomorphic volume form. A strictly pseudoconvex real hypersurface M in X inherits not only a CR-structure but a canonical coframing as well. In this article, this…

微分几何 · 数学 2007-05-23 Robert L. Bryant

We construct a surface with log terminal singularities and ample canonical class that has $K_X^2=1/48 983$ and a log canonical pair $(X,B)$ with a nonempty reduced divisor $B$ and ample $K_X+B$ that has $(K_X+B)^2 = 1/462$. Both examples…

代数几何 · 数学 2017-02-01 Valery Alexeev , Wenfei Liu

We prove a general embedding theorem for Cohen--Macaulay curves (possibly nonreduced), and deduce a cheap proof of the standard results on pluricanonical embeddings of surfaces, assuming vanishing H^1(2K_X)=0.

alg-geom · 数学 2008-02-03 F. Catanese , M. Franciosi , K. Hulek , M. Reid

The existence of essential closed surfaces surfaces is proven for finite coverings of 3-manifolds that are triangulated by finitely many topological ideal tetrahedra and admit a regular, negatively curved, ideal structure.

几何拓扑 · 数学 2021-09-03 Charalampos Charitos

Let X be a closed surface of genus two embedded in the 3-sphere. Then X inherits a metric and an orientation, which give an almost complex structure, which automatically integrates to a genuine complex structure, making X a Riemann surface.…

复变函数 · 数学 2016-07-22 Neil Strickland

We prove several boundedness statements for geometrically integral normal del Pezzo surfaces $X$ over arbitrary fields. We give an explicit sharp bound on the irregularity if $X$ is canonical or regular. In particular, we show that wild…

代数几何 · 数学 2025-04-23 Fabio Bernasconi , Gebhard Martin

We construct the first examples of rationally convex surfaces in the complex plane with hyperbolic complex tangencies. In fact, we give two very different types of rationally convex surfaces: those that admit analytic fillings by…

辛几何 · 数学 2025-02-06 Georgios Dimitroglou Rizell , Mark G. Lawrence

In this paper I investigate minimal surfaces of general type with p_g=5, q=0 for which the 1-canonical map is a birational morphism onto a surface in P^4 (so called canonical surfaces in P^4) via a structure theorem for the Hilbert…

代数几何 · 数学 2007-05-23 Christian Böhning

We construct a complete, embedded minimal surface in euclidean 3-space which has unbounded Gaussian curvature. It has infinite genus, infinitely many catenoidal type ends and one limit end.

微分几何 · 数学 2010-06-18 Martin Traizet

In this article we determine, for an infinite family of maps on the plane, the topology of the surface on which the minimal regular covering occurs. This infinite family includes all Archimedean maps.

几何拓扑 · 数学 2012-10-05 Thierry Coulbois , Daniel Pellicer , Miguel Raggi , Camilo Ramírez , Ferrán Valdez

We describe procedures for generating all 2-cell embedded simple graphs with up to a fixed number of vertices on a given surface. We also modify these procedures to generate closed 2-cell embeddings and polyhedral embeddings. We give…

组合数学 · 数学 2015-09-23 Thom Sulanke

We investigate geometric invariants of cuspidal edges on focal surfaces of regular surface. In particular, we shall clarify the sign of the singular curvature at a cuspidal edge on a focal surface using singularities of parallel surface of…

微分几何 · 数学 2026-05-19 Keisuke Teramoto

We give new contributions to the existence problem of canonical surfaces of high degree. We construct several families (indeed, connected components of the moduli space) of surfaces $S$ of general type with $p_g=5,6$ whose canonical map has…

代数几何 · 数学 2017-04-05 Fabrizio Catanese

In the present paper, we study surfaces in the four-dimensional Euclidean space $\mathbb{R}^4$. We define special principal parameters, which we call canonical, on each surface without minimal points, and prove that the surface admits (at…

微分几何 · 数学 2025-12-18 Ognian Kassabov , Velichka Milousheva

In this paper we classify certain special ruled surfaces in $\R^3$ under the general theorem of characterization of constant angle surfaces. We study the tangent developable and conical surfaces from the point of view the constant angle…

微分几何 · 数学 2009-04-10 Ana-Irina Nistor

The surfaces considered are real, rational and have a unique smooth real $(-2)$-curve. Their canonical class $K$ is strictly negative on any other irreducible curve in the surface and $K^2>0$. For surfaces satisfying these assumptions, we…

代数几何 · 数学 2018-05-17 Ilia Itenberg , Viatcheslav Kharlamov , Eugenii Shustin

A spatial surface is a compact surface embedded in the 3-sphere. In this paper, we provide several typical examples of spatial surfaces and construct a coloring invariant to distinguish them. The coloring is defined by using a multiple…

几何拓扑 · 数学 2023-10-24 Atsushi Ishii , Shosaku Matsuzaki , Tomo Murao

In this note we provide a two-dimensional family of smooth minimal threefolds of general type with canonical map of degree 96, improving the previous known bound of 72.

代数几何 · 数学 2019-11-12 Davide Frapporti , Christian Gleissner

In this paper, we show that if $X$ is a smooth variety of general type of dimension $m \geq 2$, for which its canonical map induces a double cover onto $Y$, where $Y$ is a projective bundle over $\mathbf P^1$, or onto a projective space or…

代数几何 · 数学 2015-11-24 Francisco Javier Gallego , Miguel Gonzalez , Bangere P. Purnaprajna