Our main result states that a finite semiring of order > 2 with zero which is not a ring is congruence-simple if and only if it is isomorphic to a ‘dense’ subsemiring of the endomorphism semiring of a finite idempotent commutative monoid. We also investigate those subsemirings further, addressing e.g. the question of isomorphy.

Let R be a ring, σ an injective endomorphism of R and δ a σderivation of R. We prove that if R is semiprime left Goldie then the same holds for the Ore extension R[x;σ, δ] and both rings have the same left uniform dimension.

Let K be a number field and A/K be a polarized abelian variety with absolutely trivial endomorphism ring. We show that if the Néron model of A/K has at least one fiber with potential toric dimension one, then for almost all rational primes `, the Galois group of the splitting field of the `-torsion of A is GSp2g(Z/`).

Let E be an elliptic curve, K1 its Kummer curve E/{±1}, E its square product, and K2 the split Kummer surface E /{±1}. The addition law on E gives a large endomorphism ring, which induce endomorphisms of K2. With a view to the practical applications to scalar multiplication on K1, we study the explicit arithmetic of K2.

Let $k$ be a global field, let $A$ Dedekind domain with $\text{Quot}(A) = k$, and $K$ finitely generated field. Using unified approach for both elliptic curves Drinfeld modules $M$ defined over having trivial endomorphism ring, $k= \mathbb{Q}$, $A \mathbb{Z}$ in the former case function its ring of functions regular away from fixed prime latter case, any nonzero ideal $\mathfrak{a} \lhd A$ we p...

and we know that this ring is isomorphic to Z or an order O in an imaginary quadratic field K; in fact, the ring on the right is equal to Z or O (viewed as a subring of C).1 To simplify the discussion, we shall treat the isomorphism in (1) as an equality and view elements of End(EL) as elements of Z or O. How might we construct an elliptic curve with endomorphism ring O? An obvious way is to us...

We prove that the centralizer Cφ ⊆ HomR(M,M) of a nilpotent endomorphism φ of a finitely generated semisimple left R-module RM (over an arbitrary ring R) is the homomorphic image of the opposite of a certain Z(R)-subalgebra of the full m×m matrix algebra Mm×m(R[t]), where m is the dimension (composition length) of ker(φ). If R is a finite dimensional division ring over its central subfield Z(R)...

It should be noted that the definition (introduced in [l]) of a normal endomorphism of a loop G is radically different from the usual definition for groups. Nevertheless (as shown in [2]) the two definitions are equivalent when G is a group. In particular, the present theorem generalizes one of Heerema [3]. We may add that in [2], by assuming that the loop G was Moufang, we were able to be much...

We show that the endomorphism ring of any nonzero finitely generated projective module over Leavitt path algebra LK(E) an arbitrary graph E with coefficients in a field K is isomorphic to Steinberg algebra. This yields particular every corner its turn gives K-algebra local units which Morita equivalent row-countable Moreover, we prove by projection C⁎-algebra countable ample groupoid.