- #1
Bolz
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Homework Statement
If a is both the infimum of A[itex]\subseteq \mathbb{R}[/itex] and of B[itex]\subseteq \mathbb{R}[/itex] then a is also the infimum of A[itex]\cap[/itex]B
Is this statement true or false? If true, prove it. If false, give a counterexample.
Homework Equations
The Attempt at a Solution
I think it's true because let's say A={1,2,3,4} and B={1,2,3} then A[itex]\cap[/itex]B = {1,2,3}.
Then inf {A}= 1 and inf {B} = 1.
And inf {A[itex]\cap[/itex]B} = 1.
However, I think it's false because, and correct me if I'm wrong, the infimum doesn't necessarily have to belong to the subsets A nor B to be an infimum. The infimum can also be a value outside of those sets. Which would imply that the infimum of A and B doesn't have to be equal to the infimum of A[itex]\cap[/itex]B.