## 7.46: Example for injective, label-preserving graph morphisms

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

### 7.46: Example for injective, label-preserving graph morphisms

Hi,
does someone know a graph morphism $$r=(\operatorname{\mathit{v-f}}, \operatorname{\mathit{e-f}})$$ for the De-Jure-Rule "x creates $$\alpha$$ for new object y"?
I don't get how we could create the y subject when we only have $$\operatorname{\mathit{v-f}}: V_L \rightarrow V_R$$, i.e. we can't tell the function to create anything, which didn't exist before!!

felicis

Boddlnagg
Mausschubser
Beiträge: 54
Registriert: 10. Dez 2012 12:07

### Re: 7.46: Example for injective, label-preserving graph morphisms

This is how I understand it:

The graph morphism $$r$$ can't express any newly created objects, that's true. But the rewrite rule $$rr=(L,R,r)$$ also contains $$L$$ (which consists of x in that case) and $$R$$ (which contains x and y). The graph morphism part of the rule only specifies how existing nodes should be changed. Newly created nodes are specified by whatever is in $$R$$ and not in $$L$$. The m* on Slide 48 (Module 7) would express this, since it captures the relationship between $$R$$ and $$PG'$$, although the details weren't specified in the lecture.