Re: JSH: Nearly done
From: Rick Decker (rdecker_at_hamilton.edu)
Date: 01/27/05
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Date: Wed, 26 Jan 2005 20:08:51 -0500
jstevh@msn.com wrote:
> Mark Nudelman wrote:
>
>>jstevh@msn.com wrote:
>>
>>>If any of you have an ounce of mathematical ability then meet me
>
> with
>
>>>mathematics.
>>>
>>>I dare you.
>>
>>I wish you _would_ talk about the mathematics more, rather than all
>
> the long
>
>>postings about how people are mistreating you.
>>
>>Specifically I would like you to answer two questions:
>>
>>1. Why is it easier to factor T rather than M? In another post I
>
> think you
>
>>said it's _not_ because it may have small factors, as Nora proposed.
>
>
> No.
>
> T = M^2 - j^2 = (M-j)(M+j)
>
> and j can be chosen such that M+j has any given prime you wish as a
> factor.
>
Obviously.
> So you can guarantee that the numbers you need to factor are smaller
> than M.
>
Sure (look at M - g), but not necesarily that much smaller. At any rate,
I don't see that a *full* factorization of T would be any easier than
factoring M. Fortunately, you might not need to factor T fully.
> My prototype program already does that to a certain extent, so you
> could put in some huge number into it, but it'd probably take it a few
> days to process through and more than likely, it wouldn't factor.
>
> But it would process through in a few days, even with an RSA challenge
> number.
>
> That's how fast it is.
>
You're generalizing from a rather small data set. If, say, your
algorithm had running time O(M), then adding five extra digits
to M might take 100000 times as long as it did before. (See
my response to your "polynomial time" below.)
>
>>2. What's the basis for your statement that the whole process will
>
> execute
>
>>in polynomial time?
>>
>
>
> I'm focusing on building a full method that relies only on my work, so
> it has to call itself recursively to factor, and such a method can
> potentially chew through even an RSA challenge type number in minutes.
>
> Then it's just a matter of iterating through the various combinations,
> which I've figured out are at about 150 million for the number
> generated by the first 1000 primes.
>
> Potentially this method can factor an RSA challenge sized number in
> seconds.
>
> I call that polynomial time.
You might call it that, but that certainly isn't the standard usage.
I know it's unlikely that you'll research what "polynomial time"
algorithms really are, so I'll tell you: For a factoring algorithm to
be said to run in polynomial time its running time has to be less
than some polynomial in *the number of digits* of the input.
What we're *not* looking for is some factoring algorithm that
runs, say, in 2M^2 steps when given input M. Instead, what we
want is an algorithm that has running time O((log M)^k) for
some fixed constant k. Testing trial divisors, for example,
is polynomial in M, but we're looking for something much
faster than that, namely polynomial in log M.
>
> Now, when I talk about development, I'm talking about using the method
> fully, so that it acts recursively.
>
As a rule of thumb, recursive algorithms often take longer than
the equivalent non-recursive versions. You should know this.
That said, it doesn't hurt to use recursion in a "proof of concept"
program.
> NOW you can use some other method to factor T, like elliptic curve, and
> then use that factorization, as if you can get rational x's, then you
> will have about a 50% probability per.
>
> I call that an inelegant solution and rely on my own algorithm for my
> research.
>
> However, if rational x's can be consistently found, then the
> mathematics says that the method will more than likely factor a number
> without regard to size as long as you have T factored, as only a few
> rational x's are needed with the 50% success rate per.
>
You keep trumpeting this 50% success rate. Do you have either empirical
or theoretical results to back this claim up? Not that I think it's
wrong--I just haven't seen any evidence pro or con.
> Now, all the math at the lower level has been worked out, while I
> haven't yet proven conclusively that you can get rational x's at will,
> and even for very large numbers.
You can *always* find rational solutions for x. That's not a deep
result.
>
> Maybe for really big numbers rational x's become difficult to find.
>
> But at this point, I don't see a mathematical reason why they should.
>
> I think it would be quite useful if one of you could settle the
> question.
>
Done. I'll give a proof if anyone's interested.
Regards,
Rick
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