Graphing in Desmos, I see many people limiting an equation by inequalities.
Like x =y (2 is smaller than x is smaller than 10) ( symbol in place of "is smaller than ")
But is this mathematically correct? Or are they doing un-mathematical thing using the app's liberty. I think this shouldn't be correct because if it were correct, why is there so much hype about the batman equation where complex numbers are used to limit equations?