Union
$$A \cup B =$$
{ Liskov substitution, dependency inversion, forming, interface segregation, norming, open-closed, performing, single responsibility, storming }
Symmetric Difference
$$A \ominus B =$$
{ Liskov substitution, dependency inversion, forming, interface segregation, norming, open-closed, performing, single responsibility, storming }
Difference
$$A - B =$$
{ forming, norming, performing, storming }
Difference
$$B - A =$$
{ Liskov substitution, dependency inversion, interface segregation, open-closed, single responsibility }
Cartesian Product
$$A \times B =$$
{ (forming, Liskov substitution),
(forming, dependency inversion),
(forming, interface segregation),
(forming, open-closed),
(forming, single responsibility),
(norming, Liskov substitution),
(norming, dependency inversion),
(norming, interface segregation),
(norming, open-closed),
(norming, single responsibility),
(performing, Liskov substitution),
(performing, dependency inversion),
(performing, interface segregation),
(performing, open-closed),
(performing, single responsibility),
(storming, Liskov substitution),
(storming, dependency inversion),
(storming, interface segregation),
(storming, open-closed),
(storming, single responsibility) }
SOLID