Union
$$A \cup B =$$
{ advertise, analyze, contextualize, express, identify, learn, localize, metaphysics, normative science, phenomenology }
Symmetric Difference
$$A \ominus B =$$
{ advertise, analyze, contextualize, express, identify, learn, localize, metaphysics, normative science, phenomenology }
Difference
$$A - B =$$
{ advertise, analyze, contextualize, express, identify, learn, localize }
Cartesian Product
$$A \times B =$$
{ (advertise, metaphysics),
(advertise, normative science),
(advertise, phenomenology),
(analyze, metaphysics),
(analyze, normative science),
(analyze, phenomenology),
(contextualize, metaphysics),
(contextualize, normative science),
(contextualize, phenomenology),
(express, metaphysics),
(express, normative science),
(express, phenomenology),
(identify, metaphysics),
(identify, normative science),
(identify, phenomenology),
(learn, metaphysics),
(learn, normative science),
(learn, phenomenology),
(localize, metaphysics),
(localize, normative science),
(localize, phenomenology) }
Charles Sanders Peirce