2 research outputs found
Introducing the Concept of Activation and Blocking of Rules in the General Framework for Regulated Rewriting in Sequential Grammars
We introduce new possibilities to control the application of rules based on
the preceding application of rules which can be de ned for a general model of sequential
grammars and we show some similarities to other control mechanisms as graph-controlled
grammars and matrix grammars with and without applicability checking as well as gram-
mars with random context conditions and ordered grammars. Using both activation and
blocking of rules, in the string and in the multiset case we can show computational com-
pleteness of context-free grammars equipped with the control mechanism of activation
and blocking of rules even when using only two nonterminal symbols
Beyond Generalized Multiplicities: Register Machines over Groups
Register machines are a classic model of computing, often seen as a canonical
example of a device manipulating natural numbers. In this paper, we de ne register
machines operating on general groups instead. This generalization follows the research
direction started in multiple previous works. We study the expressive power of register
machines as a function of the underlying groups, as well as of allowed ingredients (zero
test, partial blindness, forbidden regions). We put forward a fundamental connection
between register machines and vector addition systems. Finally, we show how registers
over free groups can be used to store and manipulate strings