We first show that homogeneous submanifolds with abelian normal bundle in a symmetric space of non-compact type occur as principal orbits of complex hyperpolar actions on the symmetric space. Next we show that all complex hyperpolar actions with a reflective orbit are orbit equivalent to Hermann type actions. Furthermore, we classify complex hyperpolar actions with a totally geodesic orbit in the case where the ambient symmetric space is irreducible. Also, we list up the cohomogeneities of Hermann type actions on irreducible symmetric spaces.

We construct an isomorphism between the $\overline{\partial}$-cohomology and the cohomology of the fundamental groups of toroidal groups, and get a standard form of $p$-cocycles, which was given by Vogt [6] in case of $1$-cocycles. Using differential forms via the above isomorphism enables us to obtain new results in higher dimensional cases. An explicit isomorphism between the Čech cohomology and the cohomology of the fundamental groups of complex tori is given in [5] (p.14). Our results give a generalization of this isomorphism to toroidal groups.

We extend several classical invariants of links in the 3-sphere to links in so-called quasi-cylinders. These invariants include the linking number, the Seifert form, the Alexander module, the Alexander-Conway polynomial and the Murasugi-Tristram-Levine signatures.

Let $H$ be a normal subgroup of $G$. Let $W$ be a $G$-invariant indecomposable $\mathit{RH}$-module with vertex $Q$. Let $V$ be an indecomposable direct summand of the induced module $W^{G}$. Let $W'$ and $V'$ be the Green correspondents of $W$ and $V$ in $N_{H}(Q)$ and $N_{G}(Q)$ respectively. Then we prove that $\rank_{R} V/{\rank_{R}} W=\rank_{R} V'/{\rank_{R}} W'$.

The leading coefficient of the Alexander polynomial of a knot is the most informative element derived from this invariant, and the growth of orders of the first homology of cyclic branched covering spaces is also a familiar subject. Accordingly, there are a lot of investigations in each subject. However, there is no study which deals with both subjects in the same context. In this paper, we show that the two subjects are closely related in $p$-adic number theory and dynamical systems.

In this paper we consider an integro-differential system consisting of a parabolic and a hyperbolic equation related to phase transition models. The first equation is integro-differential and of hyperbolic type. It describes the evolution of the temperature and also accounts for memory effects through a memory kernel $k$ via the Gurtin-Pipkin heat flux law. The latter equation, governing the evolution of the order parameter, is semilinear, parabolic and of the fourth order (in space). We prove a local in time existence result and a global uniqueness result for the identification problem consisting in recovering the memory kernel $k$ appearing in the first equation.

The main purpose of this paper is by using the Fourier expansion for character sums and the mean value theorems of Dirichlet $L$-functions to give some hybrid mean value results for a generalization on a problem of D.H. Lehmer and hyper-Kloosterman sums.

We study the existence and the asymptotic stability of a stationary solution to the initial boundary value problem for a one-dimensional hydrodynamic model of semiconductors. This problem is considered, in the previous researches [2] and [11], under the assumption that a doping profile is flat, which makes the stationary solution also flat. However, this assumption is too narrow to cover the doping profile in actual diode devices. Thus, the main purpose of the present paper is to prove the asymptotic stability of the stationary solution without this assumption on the doping profile. Firstly, we prove the existence of the stationary solution. Secondly, the stability is shown by an elementary energy method, where the equation for an energy form plays an essential role.

The notion of the negative slope algorithm was introduced by S. Ferenczi, C. Holton, and L. Zamboni as an induction process of three interval exchange transformations. Then S. Ferenczi and L.F.C. da Rocha gave the explicit form of its absolutely continuous invariant measure and showed that it is ergodic. In this paper we prove that the negative slope algorithm with the absolutely continuous invariant measure is weak Bernoulli. We also show that this measure is derived as a marginal distribution of an invariant measure for a 4-dimensional (natural) extension of the negative slope algorithm. We also calculate its entropy by Rohlin's formula.

Let $L$ be a very ample line bundle on a smooth curve $C$ of genus $g$ with $(3g+3)/2<\deg L\le 2g-5$. Then $L$ is normally generated if $\deg L>\max\{2g+2-4h^1(C,L), 2g-(g-1)/6-2h^1(C,L)\}$. Let $C$ be a triple covering of genus $p$ curve $C'$ with $C\stackrel{\phi}\to C'$ and $D$ a divisor on $C'$ with $4p<\deg D< (g-1)/6-2p$. Then $K_C(-\phi^*D)$ becomes a very ample line bundle which is normally generated. As an application, we characterize some smooth projective surfaces.

Temperley-Lieb algebras have been generalized to web spaces for rank 2 simple Lie algebras. Using these webs, we find a complete description of the Jones-Wenzl idempotents for the quantum $\mathfrak{sl}(3)$ and $\mathfrak{sp}(4)$ by single clasp expansions. We discuss applications of these expansions.

We prove that there exists a positive integer $\nu_{n}$ depending only on $n$ such that for every smooth projective $n$-fold of general type $X$ defined over complex numbers, $|mK_{X}|$ gives a birational rational map from $X$ into a projective space for every $m\geq \nu_{n}$. This theorem gives an affirmative answer to Severi's conjecture.