VARIOUS
Infinite paths do not actually have destinations but neither does 1/x have a value at x=infinity. — keystone
There are two different notations:
(1)
lim 1/x [x = 1 to inf] = 0
There 'inf' does not stand for an object named 'inf'. Rather, it is an informal placeholder as we may replace it with a formulation that does not invoke 'inf':
Let f = {<x 1/x> | x is a natural number greater than 0}.
lim f = 0
No mention of 'inf' there. Saying "to inf" is merely a figure of speech and does not imply that there is an object named "inf".
(2)
An extended system where there are the objects -inf and +inf.
Note that those may be any objects other than real numbers. They don't have to actually be infinite sets.
Ordinarily the stipulative (and I stress 'stipulative') definition of the division operation yields:
1/inf = 0
But there is value in saying that 1/x approaches 0 as x approaches infinity. — keystone
We don't just "say" it. We prove it.
there is value in saying that the path R L[...] approaches 1 as we descend the tree and approach 'row infinity'. — keystone
(1) You've cited two different versions of the S-B tree. Please choose one and stick with it.
In one version, 1/1 is the initial node and it is not obtained by any path. In the other version, 0/1 and 1/0 are the initial nodes, and 1/1 is the sole rational that is obtained twice by two different path, viz. R from 0/1 and L from 1/0.
In any case, 1/1 is not reached by by any finite or denumerable sequence R L[...].
And again, please choose one of the two versions and stick with it.
(2) Please stop saying "row infinity". There IS NO row infinity. We PROVE that there is no row infinity. It is not coherent mathematics to keep saying "row infinity" no matter that you put single scare quotes around it or call it a "mirage" or "fiction".
In both of these examples, infinity is a useful fiction. — keystone
Wrong. In the case of standard mathematics, we PROVE the existence of whatever objects we use. But in your case, you just hand wave that somehow there are "fictions" not defined even as abstract mathematical objects that explain your arbitrary claims.
however you want to phrase [the notion of "row infinity"]. — keystone
I don't phrase it in any way. Because I don't have the intellectual mathematical dishonesty of trying to get by with nebulous undefined hand waving terminology.
paths (as described by infinite sequences of rational numbers) — keystone
Just to be clear, I still don't know whether you understand that paths are not sequences of nodes.
it doesn't seem like a big jump to say that the limit of a SB path is analogous to the limit of a Cauchy sequence, or in other words, that the limit of infinite SB paths are nodes corresponding to real numbers. — keystone
For crying out loud, I gave you DETAILED explanation why that is incoherent.
One more time: With Cauchy sequences, there IS an object that is the limit. But with your bull, there is no object (except you preposterously and egregiously hand wave that these objects are "mirages" or "fictions").
I gave the example of sqrt(2), but you SKIPPED.
AGAIN, you can't just take a sequence and say that there is a limit; it's not enough to say that the terms of the sequence get closer to each the next - you have to PROVE that there is an object such that the terms get arbitrarily close to it.
When you just say that there is a "limit" of the sequence of paths (or now it's nodes, you keep switching). You have to PROVE that there is such a limit.
In the rational numbers, there is no limit to the sequence 1, 1.4, 1.41, 1.414, 1.4142 ... But we prove that in the reals there is a limit, viz. the least upper bound of the range of the sequence. And that least upper bound is the square root of 2.
That is, we prove that, in the reals, every bounded set has a least upper bound. {x | x^2 < 2} is bounded. So it has a least upper bound. Then we prove that the least upper bound of {x | x^2 < 2} squared is 2, thus the least upper bound of {x | x^2 < 2} = sqrt(2) . And the sequence of rationals that are approximations converges to the limit, which is sqrt(2).
You can't just say, "The terms of the sequence get closer, so PRESTO POOF OF MAGIC, there's this mystical, fictional "mirage" thing that I say is the limit!" You have to PROVE that there is such a limit.
The bottom line being that if your magical mystical mirages are merely fictions, not proven mathematical objects, then you don't have any math about them!
I don't know how I can make this any clearer for you.
it doesn't seem like a big jump to say that the limit of a SB path is analogous to the limit of a Cauchy sequence — keystone
It is a HUGE jump, because 'limit of a Cauchy sequence' has an exact mathematical definition, while 'limit of a path' in this context is undefined and your notions about it are INCOHERENT. See above
infinite paths do not end at any node (in a similar way that Cauchy sequences do not end at any rational number — keystone
There is a similarity only if we ignore, as you do, the decisive difference that the Cauchy sequences DO converge to objects that we DO prove to exist, as we don't rely on magic wand waving as you do.
And you need to drop the word "end". The Cauchy sequences do not end at a limit. The sequences do not have an end. Rather they CONVERGE. Every time you say things like "end" you only entrench in your mind a basic misconception and then add it to the landfill of misinformation on the Internet.
The issue then is that in the S-B tree, we only have nodes corresponding to the rational numbers. — keystone
First you said the rationals are the finite paths. In that case each node is the terminal node on a finite path. So a rational is a finite path and has its corresponding terminal node.
The nodes corresponding to the real numbers are fictional. — keystone
Your "fictional" is meaningless. Anyone can say, "Here are my objects that are solutions. They're fictional objects that I made up. I like them. So there ... my math! By the way, I have an answer to Goldbach's conjecture! There is an even number that is not the sum of two primes. It's a fictional number I made up. I call it 'the Emerald number'. Behold my math!" It's bull.
Comparatively, with the real number line, we do not distinguish between the rational and irrational points on the real number line. They are of the same essence. — keystone
Oh, yes, "essence". Yeah right, everyone knows what an essence is in mathematics.
Meanwhile, I'll inform you:
A rigorous formulation is that rational numbers are equivalence classes of integers. Then real numbers are equivalence classes of Cauchy sequences of rational numbers. So, strictly speaking, the set of rationals is disjoint from the set of reals. But there is an embedding of the rationals in the reals. So, in another sense of 'rationals', we take the rationals to be the image of that embedding.
Why is it important to correct you on this? Because garbargy undefined rubrics like 'essence', 'mirage', etc. only invite fallacious inferences based not on math but on mere suggestibility.
This disagreement between the S-B tree and the real number line is what I'm trying to highlight. — keystone
You're only highlighting your ignorance, confusion and dishonesty.
I've explained more than once that there is NO "disagreement" between the S-B tree and the continuum. They are both proven to exist from the mathematical axioms without inconsistency.
Indeed, if we countenance a proposal to take real numbers as the paths in the S-B tree, then presumably we get a number system isomorphic with the standard treatment. There's not a quandary about this.
I can write a program that generates all rows and stops — keystone
No, you can't.
However, I cannot execute it. The program is no less of a program just because the output doesn't exist. — keystone
If someone says I "wrote a program to do X but it doesn't do X", I wouldn't know what that would mean.
Ordinarily, by "program that does X" we mean that it does X.
The [fictitious] output is used to describe the program/execution (not the other way around). — keystone
There you go again with your "fictitious" stuff. It's bull.
A program is not specified by an outcome. A program is specified by instructions, and those instructions entail outcomes upon inputs. One such algorithm provides for printing natural numbers increasing in size and never stopping. But there is no algorithm that provides for printing every one of the natural numbers and then stopping. That is, there is a program such that for any natural number, the output will write that natural number; but there is no program that will finish writing all the natural numbers. That is, the set of natural numbers is computably enumerable but it is not finitely enumerable.