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Let $X,Y$ be metric spaces, $x^*\in X$

We define two multifunctions $F_1:X\rightrightarrows Y$,$F_2:X\rightrightarrows Y$.

We recall the upper-semi-continuity in Berge's sense :

A multifunction $F:X\rightrightarrows Y$ is said to be u.s.c-B in $x^*$ if $$\forall \mathcal O\subset Y: F(x^*)\subset \mathcal O, \exists \delta>0, \forall x\in X : x\in B(x^*,\delta) \implies F(x^*)\subset \mathcal O$$

Now we observe the following theorem:

Theorem :

If $F_1$ is closed in $x^*$, and $F_2$ is u.s.c-B and the set $F_2(x^*)$ is compact, then the application $F_1\cap F_2$ is u.s.c-B.

The demonstration of this theorem is clear and it relies on the finite coverage of open sets of the compact set $F_2(x^*)$.

My question is the following :

Under the weakened hypothesis :

  • $F_1$ is closed in $x^*$

  • $F_2(x^*)$ is bounded, not closed, and is u.s.c-B in $x^*$.

How can we show that $F_1\cap F_2$ is not u.s.c-B in $x^*$ ? I tried the direct approach but couldn't show the desired result.

I am looking for a clue on how initiate my proof OR an example which illustrates such case.

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