You're welcome. It was clear you were not going to ever get there. By the way, although I've expressed what I think you were trying to express, it still isn't what you meant. There are hidden assumptions you have yet to expose.
Really? Where did I do that?
Slow down, Tex. You now need to express your three definitions in a relatively complete and cohesive way. Then you need to express your definition for N in a relatively complete and cohesive.
Let's start from your first use of the terms base elements and their successors.
I apologize. It seems I have introduced some confusion I did not intend by using the term "von Neumann ordinal" in a non-standard way.
The Axiom of Infinity establishes the existence of a set with certain properties. The set contains the empty set and what I will call other base elements. The set contains the successors of all of its elements (which would be its base elements, and their successors, and their successors, and ...).
A set which can be considered the minimal set satisfying the axiom's conditions is the set I will call N. It includes only the empty set as a base element. The empty set is the only element of N that is not the successor another element.
So, a set X is a non-finite set if and only if |N| <= |X|, where N is the minimal set established by the Axiom of Infinity.
As can be seen you are using these terms in order to define set N, without first formally define a
base element or
its successors (which means that by this
its there is an inseparable linkage between the two definitions, where X is a set by your own words (you are using it in your definition, after all)).
By reducing N base elements into a single element (the empty set) you established N as the set of von Neumann ordinals, and then you defined injection from N to X, in order to formally define X as a non-finite set (where N is a proper subset of X and the minimal non-finite set established by the axiom of infinity).
You did not formally define base element or
its successors, and so is the case of set X, you did not define its membership function, yet you used it in your definition of X as a non-finite set.
When I struggled to define N as the minimal set, by trying to formally define base element (or base set), you "have changed the rules of the game" and imposed base set {{{}}} on it, as if N is actually X and not the minimal set (the set of von Neumann ordinals), as clearly seen in
http://www.internationalskeptics.com/forums/showpost.php?p=13191454&postcount=202.
By doing that you have created a confusion in our discussion, and I had to change N into X.
When it was done I became aware of the beautiful verity of base sets and their successors as bijective proper subsets of set X (was called N by you from now on, as seen in the link above, where V became what was N (V became the set of von Neumann ordinals)).
You ask me where you said that there is no formal definition for what I called successor set.
Well, it is my mistake, you did not directly said that but indirectly, because of the linkage between the definitions of base set and a successor set.
Here is the relevant quote, taken from
http://www.internationalskeptics.com/forums/showpost.php?p=13192465&postcount=206 :
How do you propose to express "as its one and only base member" in the predicate calculus of set theory? (Keep in mind, too, 'base member' has no formal definition, either.)
Here is your definition of successor set:
S is a successor set ⇔ ∃p∈S (S = p∪{p})
B is a base set ⇔ not a successor set.
So as can be seen, now there is a formal definition of base set, which is something that you said that it
has no formal definition, either .
In other words, without my struggle to define formal definitions to successor set (which stands at the basis of the formal definition of base set) and base set as members of set N (which was first named by you as set X), we can't be at the current point in our discussion, which enables to formally define largest successor, and use it in order to define the yes/no membership function for set N (which was actually used by you as set X, in order to define X as a non-finite set, without first define the membership function of X).
Moreover, my non-standard use of
x as a placeholder for members, or no members at all (as seen in case of {}), may open a door for direct formalization of nothingness.
Furthermore, by formally define successor set we naturally avoid Russell's paradox, since no set is its successor set, for example: N ≠ N∪{N}.
No ad hoc axioms ( as done in ZF by establish the axiom of specification
https://en.wikipedia.org/wiki/Axiom_schema_of_specification ) are needed.
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jsfisher, without being open to each other, even if we are doing mistakes, there is less chance that new notions are emerged in order to be formalized later.
In my opinion, this is how the evolution of ideas works, by mutations.
During the past 12 years I gradually tried to learn how to take it as a journey and not as a war between egos.
I invite you to establish a paradise of base sets and their successor sets:
Code:
N = {
∅, ---> {{∅}}, ---> ... <-- base sets
{∅}, ---> {{∅}, {{∅}} }, ---> ... <-- successor sets
{∅, {∅}}, ---> {{∅}, {{∅}}, {{∅}, {{∅}}}}, ---> ... <-- successor sets
{∅, {∅}, {∅, {∅}}}, ---> {{∅}, {{∅}}, {{∅}, {{∅}}}, {{∅}, {{∅}}, {{∅}, {{∅}}}}}, ---> ... <-- successor sets
... ...
}