@@ -61,3 +61,5 @@ Validation does some simple checks, so that mal-formed intervals such as `oo(1)`
## Assessment of students' answers
The algebraic equivalence answer test will apply `interval_tidy` as needed and compare the results. Currently the feedback in this situation provided by this answer test is minimal.
If the student input is an interval, it is possible to access the upper and lower boundary through the `first` and `last` Maxima functions. For example, a PRT node checking whether the boundaries of an interval are correct (but not necessarily the interval type, like `co` or `oo`) can be done checking the algebraic equivalence of the student answer `[first(ans1), last(ans1)]` and the teacher answer `[first(ta1), last(ta1)]`.