Sure it can. 0.999... by definition is the limit of the sequence (0.9, 0.99, 0.999, ...), and the limit of that sequence is easily proven to be 1.
(And before you ask, N = 1 + floor(log10 ε), in terms of the "definition of convergence" you seem to prefer.)
The fact that some a
n in some sequence is identical to the limit of that sequence (for example, in the case of sequence (
1,0,0,0,...)), can't be extended to the case that no a
n in some sequence is identical to the limit of that sequence, in terms of the definition of convergence.
N = 1 + floor(log
10 ε) can't change that fact exactly because it is in terms of the definition of convergence.
So
0.999...10 can't be easily proven to be
1 by the definition of convergence.
The best that the definition of convergence can do is to define (in the case of sequence (
0.910,
0.9910,
0.99910, ...)) that
0.999...10 or
1 are greater than any term in sequence (
0.910,
0.9910,
0.99910, ...), but it can't prove that
0.999...10 is identical to
1 (the result in the case of sequence (
1,0,0,0,...) can't be extended to the result in the case of sequence (
0.910,
0.9910,
0.99910, ...), in terms of the definition of convergence).
So your "easily proven" has no basis in terms of the definition of convergence.
So you have said. All you need is an effective method to compute this "placeholder for that is summed".
Since your reasoning is completely closed under the notion of results that are derived from forcing the finite on the infinite (exactly as done by the definition of convergence), you simply missing the fact that actual mathematics already has a well-defined effective method to compute the exact value of infinitely many elements, exactly as done by define |
N| (which is a transfinite number) as the number of elements in {1,2,3,...}.
I use this well-defined effective method in order to define
0.000...110 as the complement of number
0.999...10 to number
1, as follows:
0.999...10 +
0.000...110 =
1.
The reasoning at the basis of the construction of a number of the form
0.000...110, is derived from the different sizes of transfinite cardinalities, as follows:
0.999...10 is not identical to
1, and the sequence of partial sums, even if it has |
N| terms, does not establish -- rigorously -- that
0.999...10 is identical to
1, simply because without using also|
R| size,
0.999...10 <
1 by exactly
0.000...110, where
0.000... is a place value keeper that the number of its places is in bijection with the number of places in 0.999... .
The number of places is at most at |
N| size, so in order to actually close the gap between
0.999...10 and
1, ...
110 that is at |
R| size is needed to actually do the job.
In other words:
0.999...10 +
0.000...
110 =
1.
More comprehensive view of such reasoning is given in
http://www.internationalskeptics.com/forums/showpost.php?p=10652239&postcount=539.
------------------------------
My definition of limit (
that is always under check, exactly as any definition has to be (which is a fundamental notion that is not in the scope of scholars like jsfisher)) is as follows:
Let
X be a placeholder for that is summed.
If |
X -
L| =
0 then L is called the limit of
X.
Here are two examples of
X:
1) The sequence (1,0,0,0,...), such that |a
n -
L| =
0.
2) The sum of the addition
0.999...10 +
0.000...110 (where
L=
1), such that |(
0.999...10 +
0.000...110) -
L| =
0.