The practice of first-order logic is replete with meta-level concepts. Most notably there are meta-variables ranging over formulae, variables, and terms, and properties of syntax s...
We study the expressive power of the logics EF + F-1 , 2 and boolean combinations of 1 over ranked trees. In particular, we provide effective characterizations of those three logic...
This paper studies several applications of the notion of a presentation of a functor by operations and equations. We show that the technically straightforward generalisation of th...
Logic Programming as well as Virtual Reality applications have achieved a lot in the last few years. In this paper we present an architecture, a methodology and two simple example...