Union
$$A \cup B =$$
{ efficient (creator), failed, final (function), formal (design), material, physical, psychic, successful }
Symmetric Difference
$$A \ominus B =$$
{ efficient (creator), failed, final (function), formal (design), material, physical, psychic, successful }
Difference
$$A - B =$$
{ efficient (creator), final (function), formal (design), material }
Difference
$$B - A =$$
{ failed, physical, psychic, successful }
Cartesian Product
$$A \times B =$$
{ (efficient (creator), failed),
(efficient (creator), physical),
(efficient (creator), psychic),
(efficient (creator), successful),
(final (function), failed),
(final (function), physical),
(final (function), psychic),
(final (function), successful),
(formal (design), failed),
(formal (design), physical),
(formal (design), psychic),
(formal (design), successful),
(material, failed),
(material, physical),
(material, psychic),
(material, successful) }
Four causes