Definition:Coarser Filter on Set/Strictly Coarser

Definition
Let $X$ be a set.

Let $\mathcal P \left({X}\right)$ be the power set of $X$.

Let $\mathcal F, \mathcal F' \subset \mathcal P \left({X}\right)$ be two filters on $X$.

Let $\mathcal F \subset \mathcal F'$, that is, $\mathcal F \subseteq \mathcal F'$ but $\mathcal F \ne \mathcal F'$.

Then $\mathcal F'$ is strictly finer than $\mathcal F$.

Also known as
If $\mathcal F$ is a strictly coarser filter than $\mathcal F'$, then $\mathcal F'$ can also be referred to as a proper superfilter of $\mathcal F$.

However, this is not encouraged, as there exists the danger of confusing this with the concept of a proper filter.

Also see

 * Definition:Coarser Filter on Set


 * Definition:Finer Filter on Set
 * Definition:Strictly Finer Filter on Set


 * Definition:Comparable Filters on Set