Here is a clearer version of the pairs' game framework.
Let's play with the pairs' game, by using an expression of the form (
x,
y) as follows:
The outer "(" and ")" define Hilbert's hotel environment.
x defines the name of a given room in that environment.
y defines a room in that environment such that it can be without any visitor (notated by ()) OR with exactly one visitor (notated by

, where n is a placeholder for some visitor's name).
In the following pairs' game framework, where there is a function from rooms' names and visitors' names (such that both names are in 1-to-1 and onto from the names to the set of all natural numbers)
(1,(1))
(2,(2))
(3,(3))
(4,(4))
(5,(5))
...
is expressed by
1 → 1
2 → 2
3 → 3
4 → 4
5 → 5
...
which shows that |N| = |N|
---------------------------------------------
In the following pairs' game framework, where there is a function from rooms' names and visitors' names (such that both names are in 1-to-1 and onto from the names to the set of all natural numbers)
(1,(1))
(2,( ))
(3,(2))
(4,(3))
(5,(4))
...
is expressed by
1 → 1
2 →
3 → 2
4 → 3
5 → 4
...
which shows that |N| > |N|
---------------------------------------------
|N| > |N| is deducible only if the definition of function is:
x in X has
at most one y in Y
Such definition enables to define function even if it has an input but not any output (as seen, for example, in 2 → ).
---------------------------------------------
|N| > |N| is not deducible if the definition of function is:
x in X has
exactly one y in Y
Such definition does not enable to define function unless it has input and output (for example, 2 → is not deducible by such definition).