In this paper, we study the Euler-Lagrange system associated with the extremal sequences of the discrete Hardy-Littlewood-Sobolev inequality with the Sobolev-type critical conditions. This system comes into play in estimating bounds of the Coulomb energy and is related to the study of conformal geometry. In discrete case, we show that if the solutions of the system are summable, they must be monotonically decreasing at infinity. Moreover, the decay rates of the solutions are obtained. By estimating the infinite series, we prove that the Serrin-type condition is critical for the existence of super-solutions of the system. In addition, we also obtain analogous properties of the Euler-Lagrange system of the extremal sequences of the discrete reversed Hardy-Littlewood-Sobolev inequality.

We define a notion of adelic Euler systems for $\mathbb{G}_m$ over arbitrary number fields and prove that all such systems over $\mathbb{Q}$ are cyclotomic in nature. We deduce that all Euler systems for $\mathbb{G}_m$ over $\mathbb{Q}$ are cyclotomic, as has been conjectured by Coleman, if and only if they validate an analogue of Leopoldt's Conjecture.

In this paper, we consider the evolution of spacelike graphic hypersurfaces defined over a convex piece of hyperbolic plane $\mathscr{H}^{n}(1)$, of center at origin and radius 1, in the $(n+1)$-dimensional Lorentz-Minkowski space $\mathbb{R}^{n+1}_{1}$ along an anisotropic inverse mean curvature flow with the vanishing Neumann boundary condition, and prove that this flow exists for all the time. Moreover, we can show that, after suitable rescaling, the evolving spacelike graphic hypersurfaces converge smoothly to a piece of hyperbolic plane of center at origin and prescribed radius, which actually corresponds to a constant function defined over the piece of $\mathscr{H}^{n}(1)$, as time tends to infinity. Clearly, this conclusion is an extension of our previous work [2].

In this paper, we propose a method to study plane curves deformations in the Minkowski plane taking into consideration their geometry as well as their singularities. This method is an extension of the method proposed by Salarinoghabi and Tari to curves in the Euclidean plane. We deal in detail with all local phenomena that occur generically in 2-parameters families of curves. In each case, we obtain the geometry of the deformed curve, that is, information about inflections, vertices and lightlike points. We also obtain the behavior of the evolute/caustic of a curve at especial points and the bifurcations that can occur when the curve is deformed.

We classify the configurations of lines and conics in smooth Kummer quartics, assuming that all 16 Kummer divisors map to conics. We show that the number of conics on such a quartic is at most 800.

We study (von Neumann) regular $^*$-subalgebras of $B(H)$, which we call R$^*$-algebras. The class of R$^*$-algebras coincides with that of “E$^*$-algebras that are pre-C$^*$-algebras” in the sense of Z. Szűcs and B. Takács. We give examples, properties and questions of R$^*$-algebras. We observe that the class of unital commutative R$^*$-algebras has a canonical one-to-one correspondence with the class of Boolean algebras. This motivates the study of R$^*$-algebras as that of noncommutative Boolean algebras. We explain that seemingly unrelated topics of functional analysis, like AF C$^*$-algebras and incomplete inner product spaces, naturally arise in the investigation of R$^*$-algebras. We obtain a number of results on R$^*$-algebras by applying various famous theorems in the literature.