Union
$$A \cup B =$$
{ Correlation isn’t causation, Extraordinary claims need extraordinary evidence, Falsifiablity, Occam’s Razor, Replicability, Rule out rival hypotheses, context-free, context-sensitive, recursively enumerable, regular }
Symmetric Difference
$$A \ominus B =$$
{ Correlation isn’t causation, Extraordinary claims need extraordinary evidence, Falsifiablity, Occam’s Razor, Replicability, Rule out rival hypotheses, context-free, context-sensitive, recursively enumerable, regular }
Difference
$$B - A =$$
{ Correlation isn’t causation, Extraordinary claims need extraordinary evidence, Falsifiablity, Occam’s Razor, Replicability, Rule out rival hypotheses }
Cartesian Product
$$A \times B =$$
{ (context-free, Correlation isn’t causation),
(context-free, Extraordinary claims need extraordinary evidence),
(context-free, Falsifiablity),
(context-free, Occam’s Razor),
(context-free, Replicability),
(context-free, Rule out rival hypotheses),
(context-sensitive, Correlation isn’t causation),
(context-sensitive, Extraordinary claims need extraordinary evidence),
(context-sensitive, Falsifiablity),
(context-sensitive, Occam’s Razor),
(context-sensitive, Replicability),
(context-sensitive, Rule out rival hypotheses),
(recursively enumerable, Correlation isn’t causation),
(recursively enumerable, Extraordinary claims need extraordinary evidence),
(recursively enumerable, Falsifiablity),
(recursively enumerable, Occam’s Razor),
(recursively enumerable, Replicability),
(recursively enumerable, Rule out rival hypotheses),
(regular, Correlation isn’t causation),
(regular, Extraordinary claims need extraordinary evidence),
(regular, Falsifiablity),
(regular, Occam’s Razor),
(regular, Replicability),
(regular, Rule out rival hypotheses) }
Chomsky hierarchy