In this paper, we show that injectivity with respect to the class $mathcal{D}$  of dense monomorphisms of an idempotent and weakly hereditary closure operator of an arbitrary category  well-behaves. Indeed, if $mathcal{M}$ is a subclass of monomorphisms, $mathcal{M}cap mathcal{D}$-injectivity  well-behaves. We also introduce the notion of $(r,t)$-injectivity in the category {bf S-Act}, where $r...

Evaluators, also called \interpreters", play a variety of roles in the study of programming languages. Given this, it's surprising that we don't have a better framework for developing evaluators and specifying their relationship to each other. This paper shows that type classes in HASKELL provide an excellent framework for exploring relationships between evaluators, using abstract interpretatio...

Evaluators, also called \interpreters", play a variety of roles in the study of programming languages. Given this, it's surprising that we don't have a better framework for developing evaluators and specifying their relationship to each other. This paper shows that type classes in HASKELL provide an excellent framework for exploring relationships between evaluators, using abstract interpretatio...

This paper explores an approach for allowing type classes to be optionally declared by programmers, i.e. programmers can overload symbols without declaring their types in type classes. The type of an overloaded symbol is, if not explicitly defined in a type class, automatically determined from the anti-unification of instance types defined for the symbol in the relevant module. This depends on ...

Type classes and overloading are shown to be independent concepts that can both be added to simple higher-order logics in the tradition of Church and Gordon, without demanding more logical expressiveness. In particular, model-theoretic issues are not affected. Our metalogical results may serve as a foundation of systems like Isabelle/Pure that offer the user Haskell-style order-sorted polymorph...

We study the structure of a class of weighted Toeplitz operators and obtain a description of the commutant of each operator in this class. We make some progress towards proving that the only operator in the commutant which is not a scalar multiple of the identity operator and which commutes with a nonzero compact operator is zero. The proof of the main statement relies on a conjecture which is ...

the idea of difference sequences of real (or complex) numbers was introducedby ki zmaz cite{kizmaz}. in this paper, using the difference operator and alacunary sequence, we introduce and examine the class of sequence $bv_{theta}left(  delta,mathcal{f}right)  .$ we study some of its properties likesolidity, symmetricity, etc.

in present paper acertain convolution operator of analytic functions is defined.moreover, subordination- and superordination- preserving propertiesfor a class of analytic operators defined on the space of normalizedanalytic functions in the open unit disk is obtained. we also applythis to obtain sandwich results and generalizations of some knownresults.

in this article, we discuss measure theoretic characterizations for weighted composition operators in some operator classes on $l^{2}(sigma)$ such as, $n$-power normal, $n$-power quasi-normal, $k$-quasi-paranormal and quasi-class$a$. then we show that weighted composition operators can separate these classes.

We estimate the essential norm of a weighted composition operator relatively to the class of Dunford-Pettis operators or the class of weakly compact operators, on the space H∞ of Dirichlet series. As particular cases, we obtain the precise value of the generalized essential norm of a composition operator and of a multiplication operator.