wij <
wyni...@gmail.com> writes:
> On Thursday, 1 September 2022 at 19:27:51 UTC+8, Ben Bacarisse wrote:
>> wij <
wyni...@gmail.com> writes:
>>
>> > On Thursday, 1 September 2022 at 03:05:16 UTC+8, Keith Thompson wrote:
>> <cut>
>> >> No, lim(x->c) f(x)=L does not imply f(c)=L.
>> >
>> > Exactly what I mean.
>> > This is my point: Limit cannot yield an equal conclusion.
>> It can if someone wants it to. The reals are closed under taking the
>> least upper bounds of sets of rationals. That's how they are defined.
>> It's the whole point of the set. There are other ways to express the
>> same definition -- Cauchy sequences converge in the reals, every Dedkind
>> cut is a real, and so on -- but it's the basic definition of the set we
>> use to do calculus.
>
> The real is not closed (lots of irrationals cannot be expressed with finite
> symbols). Maybe you are talking sub-set of ℝ.
No. I think you need to learn a bit more. "Closed", on it's own is
meaningless in this context. And I meant what I said. R is closed with
respect to taking least upper bounds of sets or rationals. It is
defined so that limits do what I say they do and not what you want them
to do.
> I don't use Dedkind-cut, Cauchy sequence, theories. 1. They cannot construct
> all real numbers as claimed. 2.These theories, as definition of real number,
> should presume no real numbers exist (they seem to do circular
> argument).
They are not circular. I can't type of a whole book on the reals for
you. Read one. The definitions are not circular.
>> (There's a mass of very interesting history here with the motivation
>> that numbers like pi and e should be actual numbers. They are not
>> algebraic, so the set we want needs to be closed under some operation
>> other than taking roots of polynomials.)
>
> Number is operation/algorithm/expression (my number view). So e can be a
> number, pi should be 'unreachable' by its definition. Like my definition of ∞,
> assigning a symbol for it should work. e can be defined (of course, different
> definition here). I don't use (high-level) set theory.
> √2 is essentially an expression, so a number. One can see it as a
> 'name'.
Your mission, should you choose to accept it, is to work out the details
and try to persuade someone that it's worth looking at. (And I read
below you claim to have done the first half of that.)
>> > 'lim' should always stick to its expression, 'lim' cannot be
>> > removed.
>> In the reals, that just gives us lots of ways to write numbers. The
>> rules of real arithmetic can not distinguish between
>>
>> lim_{n->oo} 1/n!
>>
>> and
>>
>> lim_{n->oo) (1+1/n)^n
>>
>> and so we say they are equal. Do you say they are equal? (Please
>> answer this question. You are not very diligent when it comes to
>> answering clarifying questions.)
>>
>> Similarly, the rules of real arithmetic don't let us distinguish between
>> lim_{n->oo} Sum_{k=1,n} 9/10^k and 1. That's why we write 0.999... = 1.
>>
>> No one objects to "leaving the lim there" except on grounds of
>> convenience. After all, people have told you repeatedly that
>> 0.999... is just another way to write a limit. We could ditch the
>> ... and always write the limit, but there would still be no way to tell
>> the difference between that long form number "lim_{n->oo} Sum_{k=1,n}
>> 9/10^k" and "1". People will just write "1" because it's shorter.
>
> I guess a typo in the reply above.
Yes. Mike spotted it as well. But you did not answer the question.
You want to keep the limit and never say that it's actually equal to
something (at least I think that's what you meant). So if I write
lim+{n->oo} sum_{k=1,n} 1/k! and lim_{n->oo) (1+1/n)^n
can you tell is they are the same? Are they equal? Can we not just
give them a name and write e for either of them instead? Please answer.
> From the idea of information theory
> A= lim(x->∞) 1-1/n = 0.999...
> B= lim(x->∞) 1-1/2^n = 0.999...
> C= lim(x->∞) 1-1/10^n= 0.999...
> D= lim(x->∞) 1-2/10^n= 0.999...
>
> Before one determine A=B=C=D=0.999..., All such numbers(expressions) are
> distinguishable, SO WE CAN DISCUSS them.
Provided we have a meaning for the symbols. You have not given one
here. Standard textbooks give a meaning from which we conclude that
A=B=C=D=1 so you would be well-advised to use different symbols.
I can't stress this enough. Unless you are a crank trying to say that
the world is wrong about the reals, you a defining something new, so you
should use new notation.
> (We don't invent rules to make them
> equal for no GOOD and SOUND reason).
> Yes, all these could come down to the definition of 'equal'. I use the definition:
> A=B ::= The occurrence of A can be replaced by B, vice versa.
That's reasonable (except for a few details that are not really
important here). 0.999... can be used in place of 1 since they denote
the same real number.
In Wij-numbers 0.999___ =/= 1. Note the new notation so no one think
you are talking about the reals and limit of partial sums.
> To make my idea more clear, starting from infinity should be simpler:
> 123...
> 566...
> ....34
None of these have a conventional meaning and you have not explained
your number system so I can't comment. What happens if I add them,
divide them, subtract one from another etc.?
> These are all infinities (infinitely many, probably more than the first look).
> They are infinity (number) because they each can be valid expression and
> TM can be designed to represent them.... I found the simple and good way to
> handle infinity is making it unique. Therefore,
>
> '∞' ::=
> 1. ∀n∈ℕ, n<∞
> 2. The multiplicative inverse of ∞ is 1/∞, the additive inverse is -∞
>
> From this definition, others should be clear and hopefully deterministic
> (to save long discussion of 0.999... issues discussed).
That's a start. But I still don't know the rules for this new number
system. I can lookup other standard systems with infinite numbers, but
you won't say if you mean any of those. I expect not, since you want
this to be your very own invention. What's more, they are usually
extension to the reals, so 0.999... = 1 in them as well.
Maybe you want to extend the reals so can have 0.999... and 0.999___ as
well?
>> You need to say, explicitly, that you are not talking about the real
>> numbers. And you need to say what numbers you /are/ talking about. And
>> yo need to lay out the rules or arithmetic that enable someone to use
>> your set whilst as the same time distinguishing between lim_{n->oo}
>> Sum_{k=1,n} 9/10^k" and "1". It's a lot of work. Are you up for it?
>>
>> --
>> Ben.
>
> I already made my idea clear in
>
https://sourceforge.net/projects/cscall/files/MisFiles/NumberView-en.txt/download
Great. I'll assume you have done all the work. Is there any reason I
should read it?
> and mentioned many times. It was originally written for me to follow, so
> something may not be clear to readers. But, I think my idea should be clear
> enough so far. Adding these explanation to that file ruins its
> purpose.
But my posts have been about why you are wrong about the reals. I've
not said you are wrong about your own numbers. I think it's /likely/
that you are wrong about them, but I'd have to have a reason to read
about them first. And I don't see a reason. Why are they interesting?
> Real numbers are not all constructable.
True.
> I don't think real numbers can be better
> addressed without infinity (think about the vast number of irrationals not
> addressable). Some real number 'explode', some 'implode'.
> What I am talking about is really noting but from the definition of infinity.
> All should be followed, not some new theory, maybe just new
> recognition.
>
> As you can see, I cannot name what I thought differently. Because we
> are dealing the same thing (basically, the measurement of the real
> world, the distance between two points in the real space). What is in
> text-book is inconsistent, useful when the authority says you must say
> the same to gain ??? or avoid punishment (If I were taking an exam. I
> would answer the same as you would. Why not? somebody pay for it and
> I want the prize), or useful when nothing involving infinity.
Is there someone who can read over your text before posting? I find
your writing very hard to follow. I don't know what these remarks mean.
--
Ben.