Union
$$A \cup B =$$
{ being, earth, essence, grass, heaven, lake, mountain, notion, river, thunder, wood }
Symmetric Difference
$$A \ominus B =$$
{ being, earth, essence, grass, heaven, lake, mountain, notion, river, thunder, wood }
Difference
$$B - A =$$
{ earth, grass, heaven, lake, mountain, river, thunder, wood }
Cartesian Product
$$A \times B =$$
{ (being, earth),
(being, grass),
(being, heaven),
(being, lake),
(being, mountain),
(being, river),
(being, thunder),
(being, wood),
(essence, earth),
(essence, grass),
(essence, heaven),
(essence, lake),
(essence, mountain),
(essence, river),
(essence, thunder),
(essence, wood),
(notion, earth),
(notion, grass),
(notion, heaven),
(notion, lake),
(notion, mountain),
(notion, river),
(notion, thunder),
(notion, wood) }
Georg Wilhelm Friedrich Hegel