Library
▹
Essentials
▹
Numbers
▹
Cardinal numbers
Definition 1.8.2.12.
Let
κ
,
μ
be
cardinal numbers
. We define
κ
+
μ
by:
|
K
|
+
|
J
|
:
=
|
K
⊎
J
|
(
K
is a set,
J
is a set)
References.
https://en.wikipedia.org/wiki/Cardinal_number#Cardinal_addition
https://mathworld.wolfram.com/CardinalAddition.html
https://proofwiki.org/wiki/Definition:Sum_of_Cardinals
https://leanprover-community.github.io/mathlib_docs/set_theory/cardinal.html#cardinal.add_def