Hasse Divides
1. The problem asks us to draw the Hasse diagram for the partially ordered set $(\{1, 2, 3, 4, 6, 8, 12\}, \mid)$ where the order relation is divisibility: $a \leq b$ if and only if $a$ divides $b$.
2. We start by listing elements and the divisibility relations:
- $1$ divides every element.
- $2$ divides $4, 6, 8, 12$.
- $3$ divides $6, 12$.
- $4$ divides $8, 12$.
- $6$ divides $12$.
- $8$ divides none greater than itself.
- $12$ is the greatest element.
3. To draw the Hasse diagram, we include elements as nodes. Draw an edge (line) from $a$ to $b$ if $a$ divides $b$ and there is no $c$ such that $a$ divides $c$ and $c$ divides $b$ (cover relation). This excludes transitive edges.
4. The cover relations are:
- $1 \to 2, 3$ (1 divides 2 and 3, nothing in between)
- $2 \to 4, 6, 8$ (2 divides 4, 6, and 8 directly)
- $3 \to 6$
- $4 \to 8, 12$
- $6 \to 12$
5. Arrange nodes vertically so that arrows point upward. $1$ at bottom, $2$ and $3$ above it, then $4,6,8$ above those, and $12$ at the top.
6. The Hasse diagram reflects this partial order without arrows since edges go upward by convention.
Final answer: The Hasse diagram nodes and edges are as described with the relations above visualized accordingly.