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What is $[1, 5] \cap [4, 5[$? Is it $[4, 5[$ or $[4, 5]$ ?

Correct me if I'm wrong:

$A = [1,5]$ includes $\{1, 1.34, 3.23, 4, 5 \}$, and $B = [4, 5[$ includes $\{4.32, 4.44, 4.99\}$. So if I intersect $A$ and $B$, I get all value between $[4, 5[$.

Am I right? Also if it is a $A \cup B$, would it be $[1, 5]$?

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up vote 4 down vote accepted

Yes you are right. But there are more numbers in $A$ and $B$ than what you listed.

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