Union
$$A \cup B =$$
{ Attitude Skills, Fire Skills, Food Skills, Naturalist Skills, Shelter Skills, Water Skills, fetishism, monotheism, polytheism }
Symmetric Difference
$$A \ominus B =$$
{ Attitude Skills, Fire Skills, Food Skills, Naturalist Skills, Shelter Skills, Water Skills, fetishism, monotheism, polytheism }
Difference
$$B - A =$$
{ Attitude Skills, Fire Skills, Food Skills, Naturalist Skills, Shelter Skills, Water Skills }
Cartesian Product
$$A \times B =$$
{ (fetishism, Attitude Skills),
(fetishism, Fire Skills),
(fetishism, Food Skills),
(fetishism, Naturalist Skills),
(fetishism, Shelter Skills),
(fetishism, Water Skills),
(monotheism, Attitude Skills),
(monotheism, Fire Skills),
(monotheism, Food Skills),
(monotheism, Naturalist Skills),
(monotheism, Shelter Skills),
(monotheism, Water Skills),
(polytheism, Attitude Skills),
(polytheism, Fire Skills),
(polytheism, Food Skills),
(polytheism, Naturalist Skills),
(polytheism, Shelter Skills),
(polytheism, Water Skills) }