The seminal concept of characteristic polygon of an embedded algebroid surface, developed by Hironaka expanding on an idea of Newton, seems well suited for combinatorially (perhaps even effectively) tracking of a resolution process. However, the way this object evolves through the resolution of singularities is not really well understood, as some references had pointed out. The aim of this paper is

Given a positive function $u \in W^{1,n}$, we define its John–Nirenberg radius at point $x$ to be the supreme of the radius such that $\int_{B_t (x)} {\lvert \nabla \operatorname{log} u \rvert}^n \lt \epsilon^n_0$ when $n \gt 2$, and $\int_{B_t (x)} {\lvert \nabla u \rvert}^2 \lt \epsilon^2_0$ when $n = 2$. We will show that for a collapsing sequence of metrics in a fixed conformal class under some

Every compact symmetric space $M$ admits a dual noncompact symmetric space $\breve{M}$. When $M$ is a generalized Grassmannian, we can view $\breve{M}$ as an open submanifold of it, consisting of space-like subspaces [4]. Motivated from this, we study the embeddings from noncompact symmetric spaces to their compact duals, including space-like embedding for generalized Grassmannians, Borel embedding

This paper is devoted to study multiplicity and regularity of complex analytic sets. We present an equivalence for complex analytical sets, named blow-spherical equivalence and we obtain several applications with this new approach. For example, we reduce to homogeneous complex algebraic sets a version of Zariski’s multiplicity conjecture in the case of blow-spherical homeomorphism, we give some partial

The Ricci form is a moment map for the action of the group of exact volume preserving diffeomorphisms on the space of almost complex structures. This observation yields a new approach to the Weil–Petersson symplectic form on the Teichmüller space of isotopy classes of complex structures with real first Chern class zero and nonempty Kähler cone.

A smooth GKM stack is a smooth Deligne-Mumford stack equipped with an action of an algebraic torus $T$, with only finitely many zero-dimensional and one-dimensional orbits. (i) We define the stacky GKM graph of a smooth GKM stack, under the mild assumption that any one-dimensional $T$-orbit closure contains at least one $T$ fixed point. The stacky GKM graph is a decorated graph which contains enough

We prove that an $n$-dimensional $(n \geq 4)$ gradient shrinking Ricci soliton with fourth-order divergence free Riemannian curvature tensor (i.e. $\mathit{\operatorname{div}}^4 Rm = 0)$ is rigid. In particular, such a soliton in dimension $4$ is either Einstein, or a finite quotient of $\mathbb{R}^4$, $\mathbb{R}^2 \times \mathbb{S}^2$, or $\mathbb{R} \times \mathbb{S}^3$. Under the condition of

Let $p$ be an odd prime and $F_\infty$ a $p$-adic Lie extension of a number field $F$. Let $A$ be an abelian variety over $F$ which has ordinary reduction at every primes above $p$. Under various assumptions, we establish asymptotic upper bounds for the growth of Mordell–Weil rank of the abelian variety of $A$ in the said $p$-adic Lie extension. Our upper bound can be expressed in terms of invariants

A conformally invariant generalization of the Willmore energy for compact immersed submanifolds of even dimension in a Riemannian manifold is derived and studied. The energy arises as the coefficient of the log term in the renormalized area expansion of a minimal submanifold in a Poincaré–Einstein space with prescribed boundary at infinity. Its first variation is identified as the obstruction to smoothness

In this article, we will construct a plurisubharmonic function whose jumping coefficients have a cluster point. We also give a class of plurisubharmonic functions which cannot be “strongly equisingular” to any plurisubharmonic function with generalized analytic singularities and present global equisingular approximations of quasi-plurisubharmonic functions with stable analytic pluripolar sets on compact

We describe the range of the Radon transform on the space $M$ of irreducible conics in $\mathbb{CP}^2$ in terms of natural differential operators associated to the $SO(3)$-structure on $M = SL(3,\mathbb{R})/SO(3)$ and its complexification. Following [27] we show that for any function $F$ in this range, the zero locus of $F$ is a four-manifold admitting an anti-self-dual conformal structure which contains

Let $\mathscr{F}$ be a singular codimension one holomorphic foliation on a compact complex manifold $X$ of dimension at least three such that its singular set has codimension at least two. In this paper, we determine Lehmann–Suwa residues of $\mathscr{F}$ as multiples of complex numbers by integration currents along irreducible complex subvarieties of $X$. We then prove a formula that determines the

We discuss a natural extension of the Kähler reduction of Fujiki and Donaldson, which realises the scalar curvature of Kähler metrics as a moment map, to a hyperkähler reduction. Our approach is based on an explicit construction of hyperkähler metrics due to Biquard and Gauduchon. This extension is reminiscent of how one derives Hitchin’s equations for harmonic bundles, and yields real and complex

In every point of a Kähler manifold there exist special holomorphic coordinates well adapted to the underlying geometry. Comparing these Kähler normal coordinates with the Riemannian normal coordinates defined via the exponential map we prove that their difference is a universal power series in the curvature tensor and its iterated covariant derivatives and devise an algorithm to calculate this power

In this paper, we will consider generalised eigenfunctions of the Laplacian on some surfaces of infinite area. We will be interested in lower bounds on the number of nodal domains of such eigenfunctions which are included in a given bounded set. We will first of all consider finite sums of plane waves, and give a criterion on the amplitudes and directions of propagation of these plane waves which guarantees

Let $E$ be an elliptic curve defined over a number field $K$ with supersingular reduction at all primes of $K$ above $p$. If $K_\infty / K$ is a $\mathbb{Z}_p$-extension such that $E(K_\infty) [p^\infty]$ is finite and $H^2 (G_S (K_\infty), E [p^\infty]) = 0$, then we prove that the $\Lambda$-torsion subgroup of the Pontryagin dual of $\operatorname{Sel}_{p^\infty} (E / K_\infty)$ is pseudo-isomorphic

We define and study natural SU(2)-structures, in the sense of Conti–Salamon, on the total space $\mathcal{S}$ of the tangent sphere bundle of any given oriented Riemannian $3$-manifold $M$. We recur to a fundamental exterior differential system of Riemannian geometry. Essentially, two types of structures arise: the contact-hypo and the non-contact and, for each, we study the conditions for being hypo

The Hodge star mean curvature flow on a 3‑dimensional Riemannian or pseudo-Riemannian manifold is one of nonlinear dispersive curve flows in geometric analysis. Such a curve flow is integrable as its local differential invariants of a solution to the curve flow evolve according to a soliton equation. In this paper, we show that these flows on a 3‑sphere and 3‑dimensional hyperbolic space are integrable

Let $M$ be complex projective manifold, and $A$ a positive line bundle on it. Assume that $G = SU(2)$ acts on $M$ in a Hamiltonian manner, with nowhere vanishing moment map, and that this action linearizes to $A$. Then there is an associated unitary representation of $G$ on the associated algebro-geometric Hardy space, and the isotypical components are all finite dimensional. We consider the local

In this paper, we obtain a class of Virasoro modules by taking tensor products of the irreducible Virasoro modules $\Omega (\lambda, \alpha, h)$ defined in [CG1], with irreducible highest weight modules $V (\theta, h)$ or with irreducible Virasoro modules $\operatorname{Ind}_\theta (N)$ defined in [MZ2]. We obtain the necessary and sufficient conditions for such tensor product modules to be irreducible

We define a class of singularity on arbitrary pairs of a normal variety and an effective $\mathbb{R}$‑divisor on it, which we call pseudo‑$\operatorname{lc}$ in this paper. This is a generalization of the usual $\operatorname{lc}$ singularity of pairs and log canonical singularity of normal varieties introduced by de Fernex and Hacon. By giving examples of pseudo‑$\operatorname{lc}$ pairs which are

We show how to compute the Lagrangian Floer homology in the one-point blow up of the proper transform of Lagrangians submanifolds, solely in terms of information of the base manifold. As an example we present an alternative computation of the Lagrangian quantum homology in the one-point blow up of $(\mathbb{C}P^2, \omega_{FS})$ of the proper transform of the Clifford torus.

Let $\mathbb{K}$ be an imaginary quadratic field, $p$ a rational prime which splits in $\mathbb{K}$ into two distinct primes $\mathfrak{p}$ and $\mathfrak{\overline{p}}$, and $\mathbb{K}_\infty$ the unique $\mathbb{Z}_p$-extension of $\mathbb{K}$ unramified outside of $\mathfrak{p}$. For a finite abelian extension $\mathbb{L}$ of $\mathbb{K}$, we define $\mathbb{L}_\infty = \mathbb{LK}_\infty$, and

For $X$ a $d$-dimensional smooth projective variety over a field $k$ of characteristic $0$, using higher algebraic $K$-theory, we study the following two questions asked by Mark Green and Phillip Griffiths in chapter 10 of [9] (page 186-190): (1) For each positive integer $p$ satisfying $1 \leq p \leq d$, can one define the tangent space $TZ^p (X)$ to the cycle group $Z^p (X)$? (2) Obstruction issues

We study the Laplacian coflow and the modified Laplacian coflow of $G_2$-structures on the $7$-dimensional Heisenberg group. For the Laplacian coflow we show that the solution is always ancient, that is it is defined in some interval $(-\infty, T)$, with $0 \lt T \lt +\infty$. However, for the modified Laplacian coflow, we prove that in some cases the solution is defined only on a finite interval while

We prove that automorphism groups of Inoue and primary Kodaira surfaces are Jordan.

Two new classes of summing multilinear operators, factorable $(q, p)$-summing operators and $(r; p, q)$-summing operators are studied. These classes are described in terms of factorization. It is shown that operators in the first (resp., the second) class admit the factorization through the injective tensor product of Banach spaces (resp., through some Banach lattices). Applications in different contexts

The purpose of this article is to investigate the properties of the category of mixed plectic Hodge structures defined by Nekovář and Scholl [NS1]. We give an equivalent description of mixed plectic Hodge structures in terms of the weight and partial Hodge filtrations. We also construct an explicit complex calculating the extension groups in this category.

It was proved by Huisken that a mean curvature flow converges to a self-shrinker in the Euclidean space after scaling when it develops a singularity of type I. In this paper, we study a coupled flow with a mean curvature flow and a Ricci flow, and generalize his result for this Ricci-mean curvature flow. Then, as a parabolic rescaling limit, we get a self-shrinker in a gradient shrinking Ricci soliton

We show how Conway’s multivariable potential function can be constructed using braids and the reduced Gassner representation. The resulting formula is a multivariable generalization of a construction, due to Kassel–Turaev, of the Alexander–Conway polynomial in terms of the Burau representation. Apart from providing an efficient method of computing the potential function, our result also removes the

We characterize unimodular solvable Lie algebras with Vaisman structures in terms of Kähler flat Lie algebras equipped with a suitable derivation. Using this characterization we obtain algebraic restrictions for the existence of Vaisman structures and we establish some relations with other geometric notions, such as Sasakian, co‑Kähler and left-symmetric algebra structures. Applying these results we

Let $M$ be a nilmanifold with a fundamental group which is free $2$-step nilpotent on at least $4$ generators. We will show that for any nonnegative integer n there exists a self-diffeomorphism $h_n$ of $M$ such that hn has exactly $n$ fixed points and any self-map $f$ of $M$ which is homotopic to $h_n$ has at least $n$ fixed points. We will also shed some light on the situation for less generators

We consider the evolution of hypersurfaces on the unit sphere $\mathbb{S}^{n+1}$ by their mean curvature. We prove a differential Harnack inequality for any weakly convex solution to the mean curvature flow. As an application, by applying an Aleksandrov reflection argument, we classify convex, ancient solutions of the mean curvature flow on the sphere.

Let $(M, g)$ be an $n$-dimensional, compact Riemannian manifold. We will show that functions that are orthogonal to the first few Laplacian eigenfunctions have to have a large zero set. Let us assume $f \in C^0 (M)$ is orthogonal $\langle f, \phi_k \rangle = 0$ to all eigenfunctions $\phi_k$ with eigenvalue $\lambda_k \leq \lambda$. If $\lambda$ is large, then the function $f$ has to vanish on a large

We provide a partial classification of semistable Higgs bundles over simply connected Calabi–Yau manifolds. Applications to a conjecture about a special class of semistable Higgs bundles are given. In particular, the conjecture is proved for K3 and Enriques surfaces, and some related classes of surfaces.

We prove a conjecture of Gromov about non-free isometric immersions.

In this paper, using a spinorial approach, we generalize a theorem à la Alexandrov of Wang, Wang and Zhang [WWZ] to closed codimension-two spacelike submanifolds in the Minkowski spacetime for an adapted CMC condition.

Mather proved that the smooth stability of smooth maps between manifolds is a generic condition if and only if the pair of dimensions of the manifolds are ‘nice dimensions’ while topological stability is a generic condition in any pair of dimensions. And, by a result of du Plessis and Wall $C^1$-stability is also a generic condition precisely in the nice dimensions. We address the question of bi‑Lipschitz

We consider a supercritical branching process $(Z_n)$ in an independent and identically distributed random environment $\xi = (\xi_n)$. Let $W$ be the limit of the natural martingale $W_n = Z_n / E_\xi Z_n , n \geq 0$, where $E_\xi$ denotes the conditional expectation given the environment $\xi$. We find a necessary and sufficient condition for the existence of quenched weighted moments of $W$ of the

In [3], X. Chen proposed a continuity path aiming to attack the existence problem of the constant scalar curvature Kähler(cscK) metric. He also proved the openness of the path at $t \in (0, 1)$ by the standard implicit function theorem on solutions of fourth order PDE. However, the openness at $t = 0$ is quite different in nature and it is in fact a deformation result from the solution of a second

In [1], Guido De Philippis and Francesco Maggi proved global quadratic stability inequalities and derived explicit lower bounds for the first eigenvalues of the stability operators for all area-minimizing Lawson cones $M_{kh}$, except for those with\[(k, h), (h, k) \in S = \lbrace (3, 5), (2, 7), (2, 8), (2, 9), (2, 10), (2, 11) \rbrace \; \textrm{.}\]We proved the corresponding inequalities and lower

Given a submanifold $S \subset \mathbb{R}^n$ of codimension at least three, we construct an asymptotically Euclidean Riemannian metric on $\mathbb{R}^n$ with nonnegative scalar curvature for which the outermost apparent horizon is diffeomorphic to the unit normal bundle of $S$.

We study the asymptotic behavior of quantized Ding functionals along Bergman geodesic rays and prove that the slope at infinity can be expressed in terms of Donaldson–Futaki invariants and Chow weights. Based on the slope formula, we introduce a new algebro-geometric stability on Fano manifolds and show that the existence of anti-canonically balanced metrics implies our stability. The relation between