Divisor Relation induces Lattice

Theorem
Let $\left({\Z_{> 0}, \backslash}\right)$ be the ordered set comprising:
 * The set of positive integers $\Z_{> 0}$
 * The divisor relation $\backslash$ defined as:
 * $a \mathop \backslash b := \exists k \in \Z_{> 0}: b = ka$

Then $\left({\Z_{> 0}, \backslash}\right)$ is a lattice.

Proof
It follows from Divides is Partial Ordering on Positive Integers that $\left({\Z_{>0}, \backslash}\right)$ is indeed an ordered set.

Let $a, b \in \Z_{>0}$.

Let $d = \gcd \left\{{a, b}\right\}$ be the greatest common divisor of $a$ and $b$.

By definition, $d$ is the infimum of $\left\{{a, b}\right\}$.

Similarly, let $m = \operatorname{lcm} \left\{{a, b}\right\}$ be the least common multiple of $a$ and $b$.

By definition, $m$ is the supremum of $\left\{{a, b}\right\}$.

Hence, as $\left\{{a, b}\right\}$ has both an infimum and a supremum in $\Z_{>0}$, it follows that $\left({\Z_{> 0}, \backslash}\right)$ is a lattice.