Limit
$\lim_{ x \to +0 } \frac{1}{x} = \infty$
\lim_{ x \to +0 } \frac{1}{x} = \infty
It is derived from the concept of a limit.
$\displaystyle \lim_{ n \to \infty } f_n(x) = f(x)$
\displaystyle \lim_{ n \to \infty } f_n(x) = f(x)
Adding "\displaystyle" causes the expression to be displayed in a larger format. Subscripts will be positioned below the "lim" symbol.
$\limsup_{ n \to \infty } a_n$
\limsup_{ n \to \infty } a_n
It is derived from the limit superior.
$\varlimsup_{ n \to \infty } a_n$
\varlimsup_{ n \to \infty } a_n
$\liminf_{ n \to \infty } a_n$
\liminf_{ n \to \infty } a_n
It is derived from the limit inferior.
$\varliminf_{ n \to \infty } a_n$
\varliminf_{ n \to \infty } a_n
$\begin{eqnarray} \varlimsup_{ n \to \infty } a_n = \lim_{ n \to \infty } \sup_{ k \geqq n } a_k \end{eqnarray}$
\begin{eqnarray} \varlimsup_{ n \to \infty } a_n = \lim_{ n \to \infty } \sup_{ k \geqq n } a_k \end{eqnarray}
This is an example of the limit superior of a sequence.
$\begin{eqnarray} \varliminf_{ n \to \infty } A_n = \bigcup_{ n = 1 }^{ \infty } \bigcap_{ k = n }^{ \infty } A_k = \bigcup_{ n \in \mathbb{ N } } \bigcap_{ k \geqq n } A_k \end{eqnarray}$
\begin{eqnarray} \varliminf_{ n \to \infty } A_n = \bigcup_{ n = 1 }^{ \infty } \bigcap_{ k = n }^{ \infty } A_k = \bigcup_{ n \in \mathbb{ N } } \bigcap_{ k \geqq n } A_k \end{eqnarray}
Here is an example of the limit inferior of a set.
$\mathcal{O}$
\mathcal{O}
In some cases, the symbol for Landau notation is represented using the letter "O" in calligraphy fonts.