Prefix-primitivity-preserving homomorphisms

This paper aims to investigate homomorphisms which preserve p-primitive languages. A characterization of p-primitivity-preserving homomorphisms can be detected within finite steps. Also the set of square-freeness-preserving homomorphisms is shown to be a proper subfamily of the set of p-primitivity-preserving homomorphisms. For homomorphisms over an alphabet X with |X|=2, it is also shown that the set of p-primitivity-preserving homomorphisms is a proper subfamily of the set of primitivity-preserving homomorphisms. But it is conjectured to also hold for homomorphisms over an alphabet with more than two letters.     

Riesz* homomorphisms on pre-Riesz spaces consisting of continuous functions

In the theory of operators on a Riesz space (vector lattice), an important result states that the Riesz homomorphisms (lattice homomorphisms) on C(X) are exactly the weighted composition operators. We extend this result to Riesz* homomorphisms on order dense subspaces of C(X). On those subspace we consider and compare various classes of operators that extend the notion of a Riesz homomorphism. Furthermore, using the weighted composition structure of Riesz* homomorphisms we obtain several results concerning bijective Riesz* homomorphisms. In particular, we characterize the automorphism group for order dense subspaces of C(X). Lastly, we develop a similar theory for Riesz* homomorphisms on subspace of \(C_0(X)\), for a locally compact Hausdorff space X, and apply it to smooth manifolds and Sobolev spaces.     

G-dimension over local homomorphisms with respect to a semi-dualizing complex

We study the G-dimension over local ring homomorphisms with respect to a semi-dualizing complex. Some results that track the behavior of Gorenstein properties over local ring homomorphisms under composition and decomposition are given. As an application, we characterize a dualizing complex for R in terms of the finiteness of the G-dimension over local ring homomorphisms with respect to a semi-dualizing complex.     

Conic formulations of graph homomorphisms

Given graphs X and Y, we define two conic feasibility programs which we show have a solution over the completely positive cone if and only if there exists a homomorphism from X to Y. By varying the cone, we obtain similar characterizations of quantum/entanglement-assisted homomorphisms and three previously studied relaxations of these relations. Motivated by this, we investigate the properties of these “conic homomorphisms” for general (suitable) cones. We also consider two generalized versions of the Lovász theta function, and how they interact with these conic homomorphisms. We prove analogs of several results on classical graph homomorphisms as well as some monotonicity theorems. We also show that one of the generalized theta functions is multiplicative on lexicographic and disjunctive graph products.     

Uniformly finite-to-one and onto extensions of homomorphisms between strongly connected graphs

For a homomorphism between directed graphs G₁ and G₂, its extension is the mapping of the set of all paths in G₁ into the set of all paths in G₂ obtained by naturally extending it. We investigate the properties of uniformly finite-to-one and onto extensions of homomorphisms of directed graphs, essentially the properties of uniformly finite-to-one and onto extensions of homomorphisms between strongly connected directed graphs. We also describe applications of our results on homomorphisms of directed graphs to the theory of a class of symbolic flows called subshifts of finite type.     

Über komplexe Banachverbandsalgebren

It is the aim of this paper to show that complex Banach lattice algebras have a richer spectral theory than complex Banach algebras without lattice structure. Indeed, it turns out that complex Banach lattice algebras having the property that the absolute values of their complex homomorphisms are again multiplicative are interesting with respect to the Gelfand theory. For example the set of complex homomorphisms is “cyclic.” Furthermore among other things it is shown that for central homomorphisms of AL-algebras, a special class of complex Banach lattice algebras, similar results are valid as J. L. Taylor has proved them for convolution measure algebras.     

Stone style duality for distributive nearlattices

The aim of this paper is to study the variety of distributive nearlattices with greatest element. We will define the class of N-spaces as sober-like topological spaces with a basis of open, compact, and dually compact subsets satisfying an additional condition. We will show that the category of distributive nearlattices with greatest element whose morphisms are semi-homomorphisms is dually equivalent to the category of N-spaces with certain relations, called N-relations. In particular, we give a duality for the category of distributive nearlattices with homomorphisms. Finally, we apply these results to characterize topologically the one-to-one and onto homomorphisms, the subalgebras, and the lattice of the congruences of a distributive nearlattice.     

Canonical extensions of the Johnson homomorphisms to the Torelli groupoid

We prove that every trivalent marked bordered fatgraph comes equipped with a canonical generalized Magnus expansion in the sense of Kawazumi. This Magnus expansion is used to give canonical extensions of the higher Johnson homomorphisms τm, for m?1, to the Torelli groupoid, and we provide a recursive combinatorial formula for tensor representatives of these extensions. In particular, we give an explicit 1-cocycle in the dual fatgraph complex which extends τ₂ and thus answer affirmatively a question of Morita and Penner. To illustrate our techniques for calculating higher Johnson homomorphisms in general, we give explicit examples calculating τm, for m?3.     

Some Automatic Continuity Theorems for Operator Algebras and Centralizers of Pedersen’s Ideal

We prove automatic continuity theorems for “decomposable” or“local” linear transformations between certain natural subspaces of operator algebras. The transformations involved are not algebra homomorphisms but often are module homomorphisms. We show that all left (respectively quasi-) centralizers of the Pedersen ideal of a C*-algebra A are locally bounded if and only if A has no infinite dimensional elementary direct summand. It has previously been shown by Lazar and Taylor and Phillips that double centralizers of Pedersen’s ideal are always locally bounded.     

Hyperelliptic curves and homomorphisms to ideal class groups of quadratic number fields

For the function field K of hyperelliptic curves over Q we define a subgroup of the ideal class group called the group of Z-primitive ideals. We then show that there are homomorphisms from this subgroup to ideal class groups of certain quadratic number fields.     

Katoʼs residue homomorphisms and reciprocity laws on arithmetic surfaces

We explicitly study Kato?s residue homomorphisms in Milnor K-theory, which are closely related to Contou-Carrère symbols. As applications we establish several reciprocity laws for certain locally defined maps on K-groups that are associated to arithmetic surfaces.     

Local Abelian Torsion-Free Groups

A representation for p-local Abelian torsion-free groups of finite rank is obtained in terms of homomorphisms of p-adic modules of finite rank with fixed basis.     

Separating bounded group homomorphisms on ?-groups of functions

A necessary and sufficient condition is given for separating bounded group homomorphisms on ?-groups of real-valued continuous functions to be weighted composition maps.     

Convergent sequences of dense graphs I: Subgraph frequencies, metric properties and testing

We consider sequences of graphs (Gn) and define various notions of convergence related to these sequences: “left convergence” defined in terms of the densities of homomorphisms from small graphs into Gn; “right convergence” defined in terms of the densities of homomorphisms from Gn into small graphs; and convergence in a suitably defined metric.In Part I of this series, we show that left convergence is equivalent to convergence in metric, both for simple graphs Gn, and for graphs Gn with nodeweights and edgeweights. One of the main steps here is the introduction of a cut-distance comparing graphs, not necessarily of the same size. We also show how these notions of convergence provide natural formulations of Szemerédi partitions, sampling and testing of large graphs.     

The wonderland of reflections

A fundamental fact for the algebraic theory of constraint satisfaction problems (CSPs) over a fixed template is that pp-interpretations between at most countable ω-categorical relational structures have two algebraic counterparts for their polymorphism clones: a semantic one via the standard algebraic operators H, S, P, and a syntactic one via clone homomorphisms (capturing identities). We provide a similar characterization which incorporates all relational constructions relevant for CSPs, that is, homomorphic equivalence and adding singletons to cores in addition to ppinterpretations. For the semantic part we introduce a new construction, called reflection, and for the syntactic part we find an appropriate weakening of clone homomorphisms, called h1 clone homomorphisms (capturing identities of height 1).As a consequence, the complexity of the CSP of an at most countable ω-categorical structure depends only on the identities of height 1 satisfied in its polymorphism clone as well as the natural uniformity thereon. This allows us in turn to formulate a new elegant dichotomy conjecture for the CSPs of reducts of finitely bounded homogeneous structures.Finally, we reveal a close connection between h1 clone homomorphisms and the notion of compatibility with projections used in the study of the lattice of interpretability types of varieties.     

Image partition regularity of matrices whose entries are homomorphisms

A finite matrix A is image partition regular on a semigroup \((S,+)\) with identity 0 provided that whenever S is finitely colored, there must be some \(\vec {x}\) with entries from \(S{\setminus }\{0\}\) such that all entries of \(A\vec {x}\) are in some color class. Our aim in this article is to define homomorphism image partition regular and the first entries condition for matrices with entries from homomorphisms. Also we state a conclusion far stronger than the assertion that matrices with entries from homomorphisms satisfying the first entries condition are homomorphism image partition regular. In particular, we represent and work with geometric progressions by means of matrices with entries from homomorphisms.     

L p Brunn–Minkowski type inequalities for Blaschke–Minkowski homomorphisms

In this article, some Brunn–Minkowski type inequalities for (radial) Blaschke–Minkowski homomorphisms with respect to (radial) L _p Minkowski addition are established.     

Operators in pre-Riesz spaces: moduli and homomorphisms

We focus on two topics that are related to moduli of elements in partially ordered vector spaces. First, we relate operators that preserve moduli to generalized notions of lattice homomorphisms, such as Riesz homomorphisms, Riesz* homomorphisms, and positive disjointness preserving operators. We also consider complete Riesz homomorphisms, which generalize order continuous lattice homomorphisms. Second, we characterize elements with a modulus by means of disjoint elements and apply this result to obtain moduli of functionals and operators in various settings. On spaces of continuous functions, we identify those differences of Riesz* homomorphisms that have a modulus. Many of our results for pre-Riesz spaces of continuous functions lead to results on order unit spaces, where the functional representation is used.

     

Generalized left derivations acting as homomorphisms and anti-homomorphisms on Lie ideal of rings

Let R be a prime ring with characteristic different from 2 and L be a Lie ideal of R. In this paper, we characterize generalized left derivation, which acts as a homomorphisms or an anti-homomorphisms on L.