Union
$$A \cup B =$$
{ Liskov substitution, charity, dependency inversion, faith, fasting, interface segregation, open-closed, pilgrimage, prayer, single responsibility }
Symmetric Difference
$$A \ominus B =$$
{ Liskov substitution, charity, dependency inversion, faith, fasting, interface segregation, open-closed, pilgrimage, prayer, single responsibility }
Difference
$$A - B =$$
{ Liskov substitution, dependency inversion, interface segregation, open-closed, single responsibility }
Cartesian Product
$$A \times B =$$
{ (Liskov substitution, charity),
(Liskov substitution, faith),
(Liskov substitution, fasting),
(Liskov substitution, pilgrimage),
(Liskov substitution, prayer),
(dependency inversion, charity),
(dependency inversion, faith),
(dependency inversion, fasting),
(dependency inversion, pilgrimage),
(dependency inversion, prayer),
(interface segregation, charity),
(interface segregation, faith),
(interface segregation, fasting),
(interface segregation, pilgrimage),
(interface segregation, prayer),
(open-closed, charity),
(open-closed, faith),
(open-closed, fasting),
(open-closed, pilgrimage),
(open-closed, prayer),
(single responsibility, charity),
(single responsibility, faith),
(single responsibility, fasting),
(single responsibility, pilgrimage),
(single responsibility, prayer) }
SOLID