Ok, sorry we have not supported something here in v4.3, Adding in a full parser, will prevent some things. Students should be able to use %union, so please email me a question (or representative selection, with everything you need) and I'll either fix this.
Better ways of dealing with real sets, and unions of intervals is something I want to improve, so please let me have any suggestions.
Better ways of dealing with real sets, and unions of intervals is something I want to improve, so please let me have any suggestions.