Union
$$A \cup B =$$
{ avoiding, enclosure, getting, hearth, mound, roof, ruling, socially useful }
Symmetric Difference
$$A \ominus B =$$
{ avoiding, enclosure, getting, hearth, mound, roof, ruling, socially useful }
Difference
$$A - B =$$
{ enclosure, hearth, mound, roof }
Difference
$$B - A =$$
{ avoiding, getting, ruling, socially useful }
Cartesian Product
$$A \times B =$$
{ (enclosure, avoiding),
(enclosure, getting),
(enclosure, ruling),
(enclosure, socially useful),
(hearth, avoiding),
(hearth, getting),
(hearth, ruling),
(hearth, socially useful),
(mound, avoiding),
(mound, getting),
(mound, ruling),
(mound, socially useful),
(roof, avoiding),
(roof, getting),
(roof, ruling),
(roof, socially useful) }
Four temperaments