Union
$$A \cup B =$$
{ afraid, angry, disgusted, happy, lucid, nightmare, ordinary, premonitory, sad, surprised, telepathic }
Symmetric Difference
$$A \ominus B =$$
{ afraid, angry, disgusted, happy, lucid, nightmare, ordinary, premonitory, sad, surprised, telepathic }
Cartesian Product
$$A \times B =$$
{ (afraid, lucid),
(afraid, nightmare),
(afraid, ordinary),
(afraid, premonitory),
(afraid, telepathic),
(angry, lucid),
(angry, nightmare),
(angry, ordinary),
(angry, premonitory),
(angry, telepathic),
(disgusted, lucid),
(disgusted, nightmare),
(disgusted, ordinary),
(disgusted, premonitory),
(disgusted, telepathic),
(happy, lucid),
(happy, nightmare),
(happy, ordinary),
(happy, premonitory),
(happy, telepathic),
(sad, lucid),
(sad, nightmare),
(sad, ordinary),
(sad, premonitory),
(sad, telepathic),
(surprised, lucid),
(surprised, nightmare),
(surprised, ordinary),
(surprised, premonitory),
(surprised, telepathic) }
Paul Ekman