Interpretations of Successor (Õ)
lWhat are 0Õ, 0ÕÕ,
0ÕÕÕ, É really?
lStrings of symbols, or
lThings that can be
constructed from sets,
a more
primitive concept.
lTwo variations:
l0 is { }, the empty set; XÕ
is the set {X}, or
l0 is { }, the empty set; XÕ
is the set X é
{X}.
lIn the second example: 0 is
{}, 0Õ is {{}},
0ÕÕ is {{}, {{}}}, 0ÕÕÕ is {{}, {{}}, {{}, {{}}}}, É
0ÕÕ is {{}, {{}}}, 0ÕÕÕ is {{}, {{}}, {{}, {{}}}}, É
lAdvantage: 0n Õs is a set with n distinct members.