Definition:Height of Proper Ideal

Definition
Let $A$ be a commutative ring with unity.

Let $I$ be a proper ideal in $A$.

The height of $I$ is defined as:
 * $\map {\mathrm {ht} } I := \inf \set {\map {\mathrm {ht} } {\mathfrak p} : \mathfrak p \in \Spec A \text{ s.t. } I \subseteq \mathfrak p }$

where:
 * $\map {\mathrm {ht} } {\mathfrak p}$ is the height of $\mathfrak p$
 * $\Spec A$ is the prime spectrum of $A$