In this lecture, some interesting examples of open and closed sets in topological spaces are discussed which reflects few beautiful pathologies associated with these two English words "open" and "closed".
Timestamps:
0:00 - Introduction
0:40 - Examples of sets which are both open and closed
9:15 - An example of set which is open but not closed
13:15 - An example of set which is closed but not open
16:30 - An example of set which is Neither closed nor open
20:36 - What can you say about arbitrary intersection of open sets ?
28:35 - An example in Euclidean plane which helps to understand and learn ways to write mathematical logics and the intuition in our mind.
42:54 - Conclusion