Definition: A set S is a well defined collection of objects, called elements. Here "well defined" means that any given object in the world at large (abstract or concrete) is either an element of S or it isn't. Note: S is a set  x, is a proposition.
well defined
Elements that have to be defined by personal judgement. Such as the set ofgreat songs is not well-defined. But the set of the English alphabet is well-defined.
well-defined sets are sets that can identify easily while not well-defined are those that cannot determined easily :)
Elements that have to be defined by personal judgement. Such as the set ofgreat songs is not well-defined. But the set of the English alphabet is well-defined.
Well-defined working approach
yes
its not well defined because not all the students/people like the teachers,so it is not well defined
Yes, the set of happy people is not well defined.
What makes a well defined question is when you already know what it is going to be
its not well defined because not all the students/people like the teachers,so it is not well defined
Low-grade brain tumors usually have well-defined borders
Mass.