# AnimB limitations

When you try to animate a non-trivial model, it might happen that you get an internal error. It might also happen that some events are gray, which means that the animator is unable to evaluate their guards. Below we list some guidelines of how to prevent such problems. This page will be continuously updated.

## Finding the Source of the Problem

AnimB sends error messages to the "Console" (Window -> Show View -> Other -> General -> Console). This error messages might help you to find out the places of your model that you have to change.

## How To Write Your Event-B Models

AnimB cannot properly deal with every Event-B model. If you want to animate your model, you have to write it in a certain way. We give some guidelines, which you have to apply to **any** machine and **any** context.

- AnimB (currently) does not read invariants, theorems, the variant, or axioms. So changing any of them will not solve problems with the animator.
- Avoid all sorts of relational operators (<math>\pfun, \tfun, \pinj, \tinj, \psur, \tsur, \tbij,

\rel, \trel, \srel, \strel</math>).

- AnimB is not good in inferring the types of quantified variables. For each quantified variable you have to state the type of the variable. Write:

- <math>\forall x\qdot x \in PERSON \limp x \in \dom(mother)</math>
- <math>\exists x\qdot x \in PERSON \land x \in \ran(mother)</math>

Do not write:

- <math>\forall x\qdot x \in \dom(mother)</math>
- <math>\exists x\qdot x \in \ran(mother)</math>

- AnimB cannot deal with integer parameters and quantified integer variables, unless AnimB finds out that they range over a finite number of integers.