From 948da71a34fb2b761d1b6b15ad74558757d437f3 Mon Sep 17 00:00:00 2001
From: Andreas Steiger <52162439+anst-i@users.noreply.github.com>
Date: Mon, 9 Dec 2024 16:06:32 +0100
Subject: [PATCH] Update Real_Intervals.md

Added a description how to access the lower and upper boundary in a PRT.
---
 doc/en/CAS/Real_Intervals.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/doc/en/CAS/Real_Intervals.md b/doc/en/CAS/Real_Intervals.md
index 61564602b..8c163a98c 100644
--- a/doc/en/CAS/Real_Intervals.md
+++ b/doc/en/CAS/Real_Intervals.md
@@ -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)]`.
-- 
GitLab