Q: Relation between $ \bigcap_{i \in I}A_i $ and $ \bigcap_{i=1}^{n}A_i $ Let I be a nonempty set and a family of sets 
such that every element of the family is a subset of U.
$\mathcal F = \{A_i | i \in I\}$
I understand the meaning of this operation:
$$
\bigcap_{i \in I}A_i
$$
That's the intersection of all the elements of the sets of the family $\mathcal F$.
But I don't truly understand what this other operation means and what's the relation between the above one.
$$
\bigcap_{i=1}^{n}A_i
$$
I understand that this operation is also an intersection but what I am trying to understand is the relation between $\bigcap_{i \in I}A_i$ and $\bigcap_{i=1}^{n}A_i$
$$
\bigcap_{i=1}^{n}A_i
\subseteq\bigcap_{i \in I}A_i
$$
Is the relation above true?

A: The notation $$\bigcap _{i=1}^nA_i$$ 
denotes the same as 
$$ \bigcap_{i\in I}A_i$$
for the special case $I=\{1,2,\ldots, n\}$.
