Theorem:
There does not exist a set X such that if set X is a member of set U, then set X is identical to set U.
Proof:
(1) Let us suppose that there exists a set X such that if set X is a member of set U, then set X is identical to set U.
(2) Every member of set U is unique.
(3) According to (2) each member can be represented by a unique code, where in the case of infinite collection of members there is no first or last code, where each unique code is an infinitely long sequence of symbols without first or last symbol, for example:
{
...
...01001... ,
...11101... ,
...10110... ,
...11111... ,
...10101... ,
...
}
(4) The code of set U is defined by using Cantor's Diagonalization (without using any mapping between the members of two given sets), which is different than the other codes that represent its members (in this example the code of set U is ...10000...).
(In order to get a unique Cantor's Diagonalization code (in case that there is no first or last code, and also each code does not have first or last symbol) we arbitrarily choose some symbol of some arbitrary distinct code, and from there (by including the arbitrarily chosen symbol) we construct a complement "0;1" code by "moving" simultaneously from the arbitrarily chosen symbol infinitely many times (up AND left) AND (down AND right) by single steps).
(5) If set U is one of its own members, then its code (for example:...10000...) must appear in the collection of the unique codes, which represent the members of that set.
(6) But according to (4) the code of set U is defined by using Cantor's Diagonalization (without using any mapping between the members of two given sets), and in this case the code of set U is different than the codes of the members of set U (the example ...10000... can't be considered as the code of set U, if it is used as a code of a member of set U, because if ...10000... is considered as a code of a given member of set U, Cantor's Diagonalization code of set U, is different than that code by at least one symbol).
(7) According to (6) assumption (1) is false and we can conclude that there does not exist a set X such that if set X is a member of set U, then set X is identical to set U.
Q.E.D
The claim that, for example, ...10111... and ...11011..., are the same code, is false, because by using an overlap among such codes, we get the following results, which enable to distinguish between them, as follows:
...101... (self overlapping)
...1001... (this is the overlap result among ..10111... and ...11011... codes)
...10101...
...101101...
...1011101...
... etc. ad infinitum ...
The traditional mathematicians here get only the ...101... (self overlapping) case.