Modularity of PGL2(𝔽p)-representations over totally real fields

We study an analog of Serre’s modularity conjecture for projective representations ρ¯:Gal(K¯/K)→PGL2(k), where K is a totally real number field. We prove cases of this conjecture when k=F5.

Local criteria for the unit equation and the asymptotic Fermat’s Last Theorem

Let F be a totally real number field of odd degree. We prove several purely local criteria for the asymptotic Fermat’s Last Theorem to hold over F and also, for the nonexistence of solutions to the unit equation over F. For example, if two totally ramifies and three splits completely in F, then the asymptotic Fermat’s Last Theorem holds over F.

A note on values of the Dedekind zeta-function at odd positive integers

For an algebraic number field [Formula: see text], let [Formula: see text] be the associated Dedekind zeta-function. It is conjectured that [Formula: see text] is transcendental for any positive integer [Formula: see text]. The only known case of this conjecture was proved independently by Siegel and Klingen, namely that, when [Formula: see text] is a totally real number field, [Formula: see text] is an algebraic multiple of [Formula: see text] and hence, is transcendental. If [Formula: see text] is not totally real, the question of whether [Formula: see text] is irrational or not remains open. In this paper, we prove that for a fixed integer [Formula: see text], at most one of [Formula: see text] is rational, as [Formula: see text] varies over all imaginary quadratic fields. We also discuss a generalization of this theorem to CM-extensions of number fields.

The Automorphism Group of Green Algebra of 9-Dimensional Taft Hopf Algebra

Let H3 be the 9-dimensional Taft Hopf algebra, let [Formula: see text] be the corresponding Green ring of H3, and let [Formula: see text] be the automorphism group of Green algebra [Formula: see text] over the real number field ℝ. We prove that the quotient group [Formula: see text] is isomorphic to the direct product of the dihedral group of order 12 and the cyclic group of order 2, where T1 is the isomorphism class which contains the identity map and is isomorphic to a group [Formula: see text] with multiplication given by [Formula: see text].

Lower bounds for Maass forms on semisimple groups

Let $G$ be an anisotropic semisimple group over a totally real number field $F$. Suppose that $G$ is compact at all but one infinite place $v_{0}$. In addition, suppose that $G_{v_{0}}$ is $\mathbb{R}$-almost simple, not split, and has a Cartan involution defined over $F$. If $Y$ is a congruence arithmetic manifold of non-positive curvature associated with $G$, we prove that there exists a sequence of Laplace eigenfunctions on $Y$ whose sup norms grow like a power of the eigenvalue.

The Centrosymmetric Matrices of Constrained Inverse Eigenproblem and Optimal Approximation Problem

In this paper, a kind of constrained inverse eigenproblem and optimal approximation problem for centrosymmetric matrices are considered. Necessary and sufficient conditions of the solvability for the constrained inverse eigenproblem of centrosymmetric matrices in real number field are derived. A general representation of the solution is presented for a solvable case. The explicit expression of the optimal approximation problem is provided. Finally, a numerical example is given to illustrate the effectiveness of the method.

The p-adic Coates–Sinnott Conjecture over maximal orders

We prove the [Formula: see text]-adic version of the Coates–Sinnott Conjecture for all primes [Formula: see text], without assuming the vanishing of [Formula: see text]-invariants, for finite abelian extensions [Formula: see text] of a totally real number field [Formula: see text], where either the integral group ring [Formula: see text] of the Galois group [Formula: see text] is a maximal order in [Formula: see text] or [Formula: see text] is a CM-field of degree [Formula: see text] with [Formula: see text] odd and [Formula: see text], where the group ring [Formula: see text] is not a maximal order. The only assumption we have to make concerns the prime [Formula: see text], where for non-abelian fields we have to assume the Main Conjecture in Iwasawa theory and the equality of algebraic and analytic [Formula: see text]-invariants.

The Eigenvalue Complexity of Sequences in the Real Domain

The eigenvalue is one of the important cryptographic complexity measures for sequences. However, the eigenvalue can only evaluate sequences with finite symbols—it is not applicable for real number sequences. Recently, chaos-based cryptography has received widespread attention for its perfect dynamical characteristics. However, dynamical complexity does not completely equate to cryptographic complexity. The security of the chaos-based cryptographic algorithm is not fully guaranteed unless it can be proven or measured by cryptographic standards. Therefore, in this paper, we extended the eigenvalue complexity measure from the finite field to the real number field to make it applicable for the complexity measurement of real number sequences. The probability distribution, expectation, and variance of the eigenvalue of real number sequences are discussed both theoretically and experimentally. With the extension of eigenvalue, we can evaluate the cryptographic complexity of real number sequences, which have a great advantage for cryptographic usage, especially for chaos-based cryptography.

Quadratic Twists of Abelian Varieties With Real Multiplication

Let $F$ be a totally real number field and $A/F$ an abelian variety with real multiplication (RM) by the ring of integers $\mathcal {O}$ of a totally real field. Assuming $A$ admits an $\mathcal {O}$-linear 3-isogeny over $F$, we prove that a positive proportion of the quadratic twists $A_d$ have rank 0. If moreover $A$ is principally polarized and $III(A_d)$ is finite, then a positive proportion of $A_d$ have $\mathcal {O}$-rank $1$. Our proofs make use of the geometry-of-numbers methods from our previous work with Bhargava, Klagsbrun, and Lemke Oliver and develop them further in the case of RM. We quantify these results for $A/\mathbb {Q}$ of prime level, using Mazur’s study of the Eisenstein ideal. For example, suppose $p \equiv 10$ or $19 \pmod {27}$, and let $A$ be the unique optimal quotient of $J_0(p)$ with a rational point $P$ of order 3. We prove that at least $25\%$ of twists $A_d$ have rank 0 and the average $\mathcal {O}$-rank of $A_d(F)$ is at most 7/6. Using the presence of two different 3-isogenies in this case, we also prove that roughly $1/8$ of twists of the quotient $A/\langle P\rangle$ have nontrivial 3-torsion in their Tate–Shafarevich groups.