$\{\langle 1, 2 \rangle, \langle 2, 1 \rangle, \langle 1, 3 \rangle\}$

$\{\langle 1, 3 \rangle, \langle 2, 2 \rangle, \langle 2, 3 \rangle, \langle 3, 1 \rangle\}$

$\emptyset$

$\{\langle 1, 1 \rangle, \langle 1, 2 \rangle, \langle 2, 2 \rangle, \langle 2, 3 \rangle, \langle 3, 3 \rangle\}$