Teams in cooperating grammar systems

Abstract

We consider grammar systems in which several components are active at the same moment (a team of components is working). The power of such mechanisms is investigated and it is found that in many cases the team feature increases the generative capacity of grammar systems. In the so-called t-mode of derivation (a team works as much as it can) it is found that the team size does not induce an infinite hierarchy of languages. However, the family obtained in this case is a full abstract family of languages properly including ETOL.     

Tuning of a multivariable discrete time PI controller for unknown systems

Tuning of a multivariable discrete time PI controller, which uses interactions of the plant is discussed. Interactions are detected by observing the plant response to step inputs. The plant is assumed to be unknown, linear, time invariant and stable. The tuning method presented is an extension of the corresponding continuous time method (Davison 1976, Penttinen and Koivo 1980)