We introduce the notion of Parikh matrix induced by a word, a natural extension to the notion of Parikh matrix and prove a set of properties for this kind of matrices. We also study the relation between these two notions. We show that combining properties from both we obtain a more powerful tool for proving algebraic properties of words.

This paper shows how rewriting logic semantics (RLS) can be used as a computational logic framework for operational semantic definitions of programming languages. Several operational semantics styles are addressed: big-step and small-step structural operational semantics (SOS), modular SOS, reduction semantics with evaluation contexts, continuation-based semantics, and the chemical abstract machine. Each of these language definitional styles can

K is an executable semantic framework in which programming languages, calculi, as well as type systems or formal analysis tools can be defined, making use of configurations, computations and rules. Configurations organize the system/program state in units called cells, which are labeled and can be nested. Computations carry "computational meaning" as special nested list structures sequentializing computational tasks, such as fragments of program;