Union
$$A \cup B =$$
{ Decision Theory, Logic, Mathematics, Statistics, Systems Theory, Theoretical Computer-Science, confrontation, resolution, setup }
Symmetric Difference
$$A \ominus B =$$
{ Decision Theory, Logic, Mathematics, Statistics, Systems Theory, Theoretical Computer-Science, confrontation, resolution, setup }
Difference
$$B - A =$$
{ Decision Theory, Logic, Mathematics, Statistics, Systems Theory, Theoretical Computer-Science }
Cartesian Product
$$A \times B =$$
{ (confrontation, Decision Theory),
(confrontation, Logic),
(confrontation, Mathematics),
(confrontation, Statistics),
(confrontation, Systems Theory),
(confrontation, Theoretical Computer-Science),
(resolution, Decision Theory),
(resolution, Logic),
(resolution, Mathematics),
(resolution, Statistics),
(resolution, Systems Theory),
(resolution, Theoretical Computer-Science),
(setup, Decision Theory),
(setup, Logic),
(setup, Mathematics),
(setup, Statistics),
(setup, Systems Theory),
(setup, Theoretical Computer-Science) }