In this article, we describe the trace formulae of composition of several (up to four) adjoint actions of elements of the Lie algebra of a vertex operator algebra by using the Casimir elements. As an application, we give constraints on the central charge and the dimension of the Lie algebra for vertex operator algebras of class $\mathcal S$⁴. In addition, we classify vertex operator algebras of class $\mathcal S$⁴ with minimal conformal weight one under some assumptions.

The Green function of the Laplacian with the homogeneous Dirichlet boundary condition on bounded domains is considered. The variation of the Green function with respect to domain perturbations is called the Hadamard variation. In this paper, we present a unified approach to deriving the Hadamard variation. In our approach, the classical first Hadamard variation is obtained in a natural way under a less restrictive regularity assumption on the boundary smoothness. Furthermore, the second Hadamard variational formula with respective to general domain perturbations is obtained, which is an extension of the classical result of Garabedian–Schiffer in which only normal perturbation is considered.

Given a torsion pair t = $(\mathcal{T},\mathcal{F})$ in a module category R-Mod we give necessary and sufficient conditions for the associated Happel–Reiten–Smalø t-structure in $\mathcal{D}$(R) to have a heart $\mathcal{H}$_t which is a module category. We also study when such a pair is given by a 2-term complex of projective modules in the way described by Hoshino–Kato–Miyachi ([HKM]). Among other consequences, we completely identify the hereditary torsion pairs t for which $\mathcal{H}$_t is a module category in the following cases: i) when t is the left constituent of a TTF triple, showing that t need not be HKM; ii) when t is faithful; iii) when t is arbitrary and the ring R is either commutative, semi-hereditary, local, perfect or Artinian. We also give a systematic way of constructing non-tilting torsion pairs for which the heart is a module category generated by a stalk complex at zero.

We give a proof of the Ohsawa–Takegoshi extension theorem with sharp estimates. The proof is based on ideas of Błocki to use variations of domains to simplify his proof of the Suita conjecture, and also uses positivity properties of direct image bundles.

We consider the Yamabe equation on a complete non-compact Riemannian manifold and study the condition of stability of solutions. If (M^m, g) is a closed manifold of constant positive scalar curvature, which we normalize to be m(m − 1), we consider the Riemannian product with the n-dimensional Euclidean space: (M^m × ℝⁿ, g + g_E). And we study, as in [2], the solution of the Yamabe equation which depends only on the Euclidean factor. We show that there exists a constant λ (m,n) such that this solution is stable if and only if λ₁ ≥ λ (m,n), where λ₁ is the first positive eigenvalue of −Δ_g. We compute λ (m,n) numerically for small values of m,n showing in these cases that the Euclidean minimizer is stable in the case M = S^m with the metric of constant curvature. This implies that the same is true for any closed manifold with a Yamabe metric.

We discuss the Fourier–Borel transform for the dual of spaces of monogenic functions. This transform may be seen as a restriction of the classical Fourier–Borel transform for holomorphic functionals, and it transforms spaces of monogenic functionals into quotients of spaces of entire holomorphic functions of exponential type. We prove that, for the Lie ball, these quotient spaces are isomorphic to spaces of monogenic functions of exponential type.

We close a gap in the theory of integration for weakly geometric rough paths in the infinite-dimensional setting. We show that the integral of a weakly geometric rough path against a sufficiently regular one form is, once again, a weakly geometric rough path.

We consider the Hadamard variational formula for the Green function of the Stokes equations with the Dirichlet boundary condition under the smooth perturbation without assuming the volume preserving property. We establish the formula for the first and the second variation for the second order perturbation.

In this paper, we proved decay properties of solutions to the Stokes equations with surface tension and gravity in the half space R₊^N = {(x′, x_N) | x′ ∈ R^N−1, x_N > 0} (N ≥ 2). In order to prove the decay properties, we first show that the zero points λ_± of Lopatinskii determinant for some resolvent problem associated with the Stokes equations have the asymptotics: λ_± = ± ic_g^1/2|ξ′|^1/2 − 2|ξ′|² + O(|ξ′|^5/2) as |ξ′| → 0, where c_g > 0 is the gravitational acceleration and ξ′ ∈ R^N−1 is the tangential variable in the Fourier space. We next shift the integral path in the representation formula of the Stokes semi-group to the complex left half-plane by Cauchy's integral theorem, and then it is decomposed into closed curves enclosing λ_± and the remainder part. We finally see, by the residue theorem, that the low frequency part of the solution to the Stokes equations behaves like the convolution of the (N − 1)-dimensional heat kernel and ℱ_ξ′⁻¹[e^{± ic_g1/2|ξ′|1/2t}](x′) formally, where ℱ_ξ′⁻¹ is the inverse Fourier transform with respect to ξ′. However, main task in our approach is to show that the remainder part in the above decomposition decay faster than the residue part.

We derive formulae for some ratios of the Macdonald functions by using their zeros, which are simpler and easier to treat than known formulae. The result gives two applications in probability theory and one in classical analysis. We show a formula for the Lévy measure of the distribution of the first hitting time of a Bessel process and an explicit form for the expected volume of the Wiener sausage for an even dimensional Brownian motion. In addition, we show that the complex zeros of the Macdonald functions are the roots of some algebraic equations with real coefficients.

We introduce a new class of perturbations of the Seiberg–Witten equations. Our perturbations offer flexibility in the way the Seiberg–Witten invariants are constructed and also shed a new light to LeBrun's curvature inequalities.

In this paper we present many new families of identities for multiple harmonic sums using binomial coefficients. Some of these generalize a few recent results of Hessami Pilehrood, Hessami Pilehrood and Tauraso [Trans. Amer. Math. Soc. 366 (2014), pp.3131–3159]. As applications we prove several conjectures involving multiple zeta star values (MZSV): the Two-one formula conjectured by Ohno and Zudilin, and a few conjectures of Imatomi et al. involving 2-3-2-1 type MZSV, where the boldfaced 2 means some finite string of 2's.

The Buchstaber invariant s(K) is defined to be the maximum integer for which there is a subtorus of dimension s(K) acting freely on the moment-angle complex associated with a finite simplicial complex K. Analogously, its real version s_ℝ(K) can also be defined by using the real moment-angle complex instead of the moment-angle complex. The importance of these invariants comes from the fact that s(K) and s_ℝ(K) distinguish two simplicial complexes and are the source of nontrivial and interesting combinatorial tasks. The ultimate goal of this paper is to compute the real Buchstaber invariants of skeleta K = Δ_m−p−1^m−1 of the simplex Δ^m−1 by making a formula. In fact, it can be solved by integer linear programming. We also give a counterexample to the conjecture which is proposed in [6] and we provide an adjusted formula which can be thought of as a preperiodicity of some numbers related to the real Buchstaber invariants.

We consider the orbit type filtration on a manifold with a locally standard torus action and study the corresponding spectral sequence in homology. When all proper faces of the orbit space are acyclic and the free part of the action is trivial, this spectral sequence can be described in full. The ranks of diagonal terms of its second page are equal to h′-numbers of a simplicial poset dual to the orbit space. Betti numbers of a manifold with a locally standard torus action are computed: they depend on the combinatorics and topology of the orbit space but not on the characteristic function.

A toric space whose orbit space is the cone over a Buchsbaum simplicial poset is studied by the same homological method. In this case the ranks of the diagonal terms of the spectral sequence at infinity are the h″-numbers of the simplicial poset. This fact provides a topological evidence for the nonnegativity of h″-numbers of Buchsbaum simplicial posets and links toric topology to some recent developments in enumerative combinatorics.

Many compactly generated pseudo-groups of local transformations on 1-manifolds are realizable as the transverse dynamic of a foliation of codimension 1 on a compact manifold of dimension 3 or 4.

Kulkarni showed that, if g is greater than 3, a periodic map on an oriented surface Σ_g of genus g with order not smaller than 4g is uniquely determined by its order, up to conjugation and power. In this paper, we show that, if g is greater than 30, the same phenomenon happens for periodic maps on the surfaces with orders more than 8g/3, and, for any integer N, there is g > N such that there are periodic maps of Σ_g of order 8g/3 which are not conjugate up to power each other. Moreover, as a byproduct of our argument, we provide a short proof of Wiman's classical theorem: the maximal order of periodic maps of Σ_g is 4g + 2.

We show the existence of a weight filtration on the equivariant homology of real algebraic varieties equipped with a finite group action, by applying group homology to the weight complex of McCrory and Parusiński. If the group is of even order, we can not extract additive invariants directly from the induced spectral sequence.

Nevertheless, we construct finite additive invariants in terms of bounded long exact sequences, recovering Fichou's equivariant virtual Betti numbers in some cases. In the case of the two-elements group, we recover these additive invariants by using globally invariant chains and the equivariant version of Guillén and Navarro Aznar's extension criterion.