Let p be an odd prime number. We prove the existence of certain infinite families of imaginary quadratic fields in which p splits and for which the Iwasawa λ-invariant of the cyclotomic ℤₚ-extension is equal to 1.

We give precise estimates for the number of classical weight one specializations of a non-CM family of ordinary cuspidal eigenforms. We also provide examples to show how uniqueness fails with respect to membership of weight one forms in families.

We show that the discriminant of the generalized Laguerre polynomial $L_n^{\left(\alpha \right)}\left(x\right)$ is a non-zero square for some integer pair $(n,\alpha )$, with $n\ge 1$, if and only if $(n,\alpha )$ belongs to one of $30$ explicitly given infinite sets of pairs or to an additional finite set of pairs. As a consequence, we obtain new information on when the Galois group of $L_n^{\left(\alpha \right)}\left(x\right)$ over $\mathbb{Q}$ is the alternating group $A_n$. For example, we establish that for all but finitely many positive integers $n\equiv 2(mod4)$, the only $\alpha$ for which the Galois group of $L_n^{\left(\alpha \right)}\left(x\right)$ over $\mathbb{Q}$ is $A_n$ is $\alpha =n$.

Let $p\ge 3$ be a prime, let $n\>m\ge 1$. Let ${\pi }_n$ be the norm of ${\zeta }_{p^n}-1$ under $C_{p-1}$, so that ${\mathbb{Z}}_{\left(p\right)}\left[{\pi }_n\right]|{\mathbb{Z}}_{\left(p\right)}$ is a purely ramified extension of discrete valuation rings of degree $p^{n-1}$. The minimal polynomial of ${\pi }_n$ over $\mathbb{Q}\left({\pi }_m\right)$ is an Eisenstein polynomial; we give lower bounds for its coefficient valuations at ${\pi }_m$. The function field analogue, as introduced by Carlitz and Hayes, is studied as well.

Let $\mathbb{Q}\left(\alpha \right)$ be an algebraic number field given by the minimal polynomial $f$ of $\alpha$. We want to determine all subfields $\mathbb{Q}\left(\beta \right)\subset \mathbb{Q}\left(\alpha \right)$ of given degree. It is convenient to describe each subfield by a pair $(g,h)\in \mathbb{Z}\left[t\right]\times \mathbb{Q}\left[t\right]$ such that $g$ is the minimal polynomial of $\beta =h\left(\alpha \right)$. There is a bijection between the block systems of the Galois group of $f$ and the subfields of $\mathbb{Q}\left(\alpha \right)$. These block systems are computed using cyclic subgroups of the Galois group which we get from the Dedekind criterion. When a block system is known we compute the corresponding...

We consider the problem of determining whether a given prime p is a congruent number. We present an easily computed criterion that allows us to conclude that certain primes for which congruency was previously undecided, are in fact not congruent. As a result, we get additional information on the possible sizes of Tate-Shafarevich groups of the associated elliptic curves. We also present a related criterion for primes p such that $16$ divides the class number of the imaginary quadratic field ℚ(√-p)....