Hi,

what is the proper way of dealing with negative infinity in STACK? Maxima is providing the symbol `minf`

for limits and if I use `ta: limit(-x^3,x,inf)`

to calculate a correct answer the student will be told to type this answer as `minf`

. The expression `-inf`

(despite of looking exactly the same in the validation) won't be accepted (with answer test AlgEquiv).

On the other hand when dealing with intervals `-inf`

is occuring as well. E.g. `natural_domain(sqrt(-x))`

evaluates to `realset(x,oc(-inf,0))`

.

Is there a robust way to just use one or the other? I think it can be really confusing for students, especially if two different syntaxes would occure in the same question.

Stephan.