**5.1 Example**

Immigration rules for citizen as a knowledge base in the FOPL

```
1.∀x ∀y (stateEU(y) & citizen(x,y) ! enter(x))
```
2.∀x ∀y (¬**stateEU**(y) & **citizen**(x,y) & **has**\_**visa**(x) ! **enter**(x))

**citizen**(anne, aus), **citizen**(achim,tur), **has**-**visa**(achim), **stateEU**(aus), ¬**stateEU**(tur).
