Question 1: However, the compact ________ are "absolutely closed" in a certain sense.  

Question 2: In a ________, a set is closed if and only if it coincides with its closure.  

Question 3: An alternative characterization of closed sets is available via ________ and nets.  

Question 4: In a firstcountable space (such as a metric space), it is enough to consider only convergent ________, instead of all nets.  

Question 5: In particular, the ________ and the whole space are closed.  

Question 6: The closed interval [a,b] of ________ is closed.  

Question 7: In a ________, such as in real analysis, a closed set can be defined as a set which contains all its limit points.  

Question 8: The unit interval [0,1] is closed in the metric space real numbers, and the set [0,1] ∩ Q of ________ between 0 and 1 (inclusive) is closed in the space of rational numbers, but [0,1] ∩ Q is not closed in the real numbers.  

Question 9: In topology and related branches of ________, a closed set is a set whose complement is an open set.  

Question 10: Sets that can be constructed as the union of ________ closed sets are denoted F_{σ} sets.  

