## 4.23/4.25: Difference R_weird and LABELS

felicis
BASIC-Programmierer
Beiträge: 114
Registriert: 14. Apr 2015 20:25

### 4.23/4.25: Difference R_weird and LABELS

Hi,

I didn't really get the difference between $$\mathscr{R}$$ and the set $$LABELS$$? They are both parameters and thus arbitrarily chosen....

best
felicis

PS: I tried to reproduce the curly R, but the font which was used is Blackadder ITC, a commercial font (acquirable for ~\$40), and therefore not usable by everyone who doesn't have Windows and of course not in this forum or any mathjax/latex-like setting.....

Markus Tasch
BASIC-Programmierer
Beiträge: 124
Registriert: 11. Sep 2015 10:57

### Re: 4.23/4.25: Difference R_weird and LABELS

The usage of two parameters in the definition allows you to restrict the allowed labels $$l \in LABELS$$ by excluding certain instances in your definition of the rules $$\mathcal{R}$$.

While in most cases $$LABELS = \mathcal{R}$$ holds, this gives additional freedom in the design of your system. For instance, you may define a rather generic set of of labels $$LABELS$$ and, depending on the concrete scenario you are in, choose different sets of rules $$\mathcal{R}$$. This allows you to reuse the generic variant of $$LABELS$$ even though in certain scenarios you do not want all of these labels to possible.
Markus Tasch, M.Sc.
Modeling and Analysis of Information Systems
Department of Computer Science, TU Darmstadt