In this article we prove Adams inequality with exact growth condition in the four dimensional hyperbolic space $\mathbb{H}^4,$ \begin{align} \int_{\mathbb{H}^4} \frac{e^{32 \pi^2 u^2} - 1}{(1 + |u|)^2} \ dv_g \leq C ||u||^2_{L^2({\mathbb{H}^4})}. \end{align} for all $u \in C^{\infty}_c(\mathbb{H}^4) $ with $\int_{\mathbb{H}^4} (P_2 u) u \ dv_g \leq 1.$ We will also establish an Adachi-Tanaka type inequality in this settings. Another aspect of this article is the P.L.Lions lemma in the hyperbolic space. We prove P.L.Lions lemma for the Moser functional and for a few cases of the Adams functional on the whole hyperbolic space.

Debabrata Karmakar

In a recent expository article (Notices of the AMS, 58 (2011), no. 1, 20-27), Ezhov, McLaughlin and Schmalz showed how to perform in an effective way Tanaka's prolongation procedure valid generally for filtered structures of constant type when the distribution is equipped with an integrable complex structure, so as to derive the principal curvature invariants and (co)frame(s) associated to strongly pseudoconvex real hypersurfaces M3 in C2, an approach which is alternative and complementary to the `hyperspherical' connection of Elie Cartan, and to the so-called calculi of Fefferman, of Chern-Moser, of Webster. By choosing an initial frame for TM which is explicit in terms of a local graphing function v = f(x, y, u) for M, we provide a Cartan-Tanaka connection all elements of which are completely explicit in terms of f(x, y, u), assuming only C6-smoothness of M. The Gaussian requirement for systematic computational effectiveness then shows - a bit unexpectedly - that the two main curvatures are rational differential expressions in the sixth-order jet of f(x, y, u), the lengths of which are about 1000 pages long on a computer - just for the simplest instance of local embedded CR geometry. Large parts of the memoir aim at formulating general statements that will be useful for further constructions of Cartan-Tanaka connections related to the equivalence problem for (local) embedded CR manifolds whose CR-automorphism group is not semi-simple, cf. e.g. some model lists by Beloshapka.

Mansour Aghasi Joel Merker Masoud Sabzevari

We obtain a generalization of the Picone inequality which, in combination with the classical Picone inequality, appears to be useful for problems with the $(p,q)$-Laplace type operators. With its help, as well as with the help of several other known generalized Picone inequalities, we provide some nontrivial facts on the existence and nonexistence of positive solutions to the zero Dirichlet problem for the equation $-\Delta_p u -\Delta_q u = f_\mu(x,u,\nabla u)$ in a bounded domain $\Omega \subset \mathbb{R}^N$ under certain assumptions on the nonlinearity and with a special attention to the resonance case $f_\mu(x,u,\nabla u) = \lambda_1(p) |u|^{p-2} u + \mu |u|^{q-2} u$, where $\lambda_1(p)$ is the first eigenvalue of the $p$-Laplacian.

Vladimir Bobkov Mieko Tanaka

The backreaction of nonlinear inhomogeneities to the cosmic expansion is analyzed in the framework of general relativity with a cosmological constant. By defining the spatially averaged matter energy density, we find that the cosmological constant induces a new type of backreaction whose equation of state is $p=-4/3 \rho$, where $\rho$ and $p$ are the effective energy density and effective pressure of the backreaction in the averaged Friedmann universe. However, the effective density is negative, and thus it decreases the acceleration caused by the cosmological constant.

Hisako Tanaka Toshifumi Futamase

We present a construction of gauge theory which its structure group is not a Lie group, but a Moufang loop which is essentially non-associative. As an example of non-associative algebra, we take octonions with norm one as a Moufang loop, with which we can produce an octonionic gauge theory. Our octonionic gauge theory is a natural generalization of Maxwell U(1)= S^1 gauge theory and Yang-Mills SU(2)= S^3 gauge theory. We also give the BPST like instanton solution of our octonionic gauge theory in 8 dimension.

Takayoshi Ootsuka Erico Tanaka Eugene Loginov

The purpose of this paper is to propose methods for verifying the positivity of a weak solution $ u $ of an elliptic problem assuming $ H^1_0 $-error estimation $ \left\|u-\hat{u}\right\|_{H_{0}^{1}} \leq \rho $ given some numerical approximation $ \hat{u} $ and an explicit error bound $ \rho $. We provide a sufficient condition for the solution to be positive and analyze the range of application of our method for elliptic problems with polynomial nonlinearities. We present numerical examples where our method is applied to some important problems.

Kazuaki Tanaka

We examine the idea that our universe began as a baby universe and show that this is feasible in a $U(1)_{B-L}$ extension of the Standard Model with the classically conformal principle. The framework is consistent with current cosmological data and predicts a heavy neutral gauge boson, which could be detected at colliders.

Qing-Hong Cao Masanori Tanaka Jun-Chen Wang Ke-Pan Xie Jing-Jun Zhang

In this note we present some uniqueness and comparison results for a class of problem of the form \begin{equation} \label{EE0} \begin{array}{c} - L u = H(x,u,\nabla u)+ h(x), \quad u \in H^1_0(\Omega) \cap L^{\infty}(\Omega), \end{array} \end{equation} where $\Omega \subset \R^N$, $N \geq 2$ is a bounded domain, $L$ is a general elliptic second order linear operator with bounded coefficients and $H$ is allowed to have a critical growth in the gradient. In some cases our assumptions prove to be sharp.

David Arcoya Colette De Coster Louis Jeanjean Kazunaga Tanaka

We study in detail the existence, nonexistence and behavior of global minimizers, ground states and corresponding energy levels of the $(p,q)$-Laplace equation $-\Delta_p u -\Delta_q u = \alpha |u|^{p-2}u + \beta |u|^{q-2}u$ in a bounded domain $\Omega \subset \mathbb{R}^N$ under zero Dirichlet boundary condition, where $p > q > 1$ and $\alpha, \beta \in \mathbb{R}$. A curve on the $(\alpha,\beta)$-plane which allocates a set of the existence of ground states and the multiplicity of positive solutions is constructed. Additionally, we show that eigenfunctions of the $p$- and $q$-Laplacians under zero Dirichlet boundary condition are linearly independent.

Vladimir Bobkov Mieko Tanaka

We investigate the existence and multiplicity of abstract weak solutions of the equation $-\Delta_p u -\Delta_q u=\alpha |u|^{p-2}u + \beta |u|^{q-2}u$ in a bounded domain under zero Dirichlet boundary conditions, assuming $1<q<p$ and $\alpha,\beta \in \mathbb{R}$. We determine three generally different ranges of parameters $\alpha$ and $\beta$ for which the problem possesses a given number of distinct pairs of solutions with a prescribed sign of energy. As auxiliary results, which are also of independent interest, we provide alternative characterizations of variational eigenvalues of the $q$-Laplacian using narrower and larger constraint sets than in the standard minimax definition.

Vladimir Bobkov Mieko Tanaka