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| Arturo Magidin |
Posted: Mon Apr 14, 2008 10:03 am |
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In article <1b338aaf-b3e7-4496-864b-baf8f7758911@w8g2000prd.googlegroups.com>,
Student of Math <omar.hosseiny@gmail.com> wrote:
Quote: I have proved that any uncountable subset of real numbers has the
same
cardinality as that of the set of all of real numbers.
I do not believe that whatever it is that your argument is establishes
this.
Prove me wrong.
--
======================================================================
"It's not denial. I'm just very selective about
what I accept as reality."
--- Calvin ("Calvin and Hobbes" by Bill Watterson)
======================================================================
Arturo Magidin
magidin-at-member-ams-org |
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| Arturo Magidin |
Posted: Mon Apr 14, 2008 10:05 am |
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In article <1b338aaf-b3e7-4496-864b-baf8f7758911@w8g2000prd.googlegroups.com>,
Student of Math <omar.hosseiny@gmail.com> wrote:
Quote: I have proved that any uncountable subset of real numbers has the
same
cardinality as that of the set of all of real numbers.
You do know that not every uncountable subset of the real numbers is
an interval, right?
Quote: In fact I have proved that continuum and uncountable are equivalent
mathematical concepts.
This is nonsense. Uncountable means "infinite and not countable."
The set of all subsets of the real numbers is provably uncountable,
and is also provably of cardinality strictly larger than that of the
continuum; hence it is THEOREM that "uncountable" and "same
cardinality as the continuum" are ->not<- equivalent. So either you
are working with different definitions, or you are wrong.
--
======================================================================
"It's not denial. I'm just very selective about
what I accept as reality."
--- Calvin ("Calvin and Hobbes" by Bill Watterson)
======================================================================
Arturo Magidin
magidin-at-member-ams-org |
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| Student of Math |
Posted: Mon Apr 14, 2008 10:10 am |
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On Apr 14, 11:02 pm, magi...@math.berkeley.edu (Arturo Magidin) wrote:
Quote: In article <95521eae-e92a-483b-a8d0-13629b0d2...@x19g2000prg.googlegroups.com>,
Student of Math <omar.hosse...@gmail.com> wrote:
On Apr 14, 6:41=A0pm, magi...@math.berkeley.edu (Arturo Magidin) wrote:
[...]
it is just archimedian property of real numbers that i assume to
prove continuum hypothesis.
Can you please STATE the continuum hypothesis? I have the strong
suspicion that you cannot state it.
As you must know Archimedian property of real numbers is independent
from ZFC.
No, you are incorrect. The Archimedean property of the real numbers is
a THEOREM of ZFC.
What is true is that the Archimedean property is independent of the
field axioms (and of other axiomatic systems for algebra). However,
the fact that the REAL NUMBERS form an Archimedean field is a
perfectly fine theorem of ZF, it is NOT independent from ZF.
--
=====================================================================> "It's not denial. I'm just very selective about
what I accept as reality."
--- Calvin ("Calvin and Hobbes" by Bill Watterson)
=====================================================================
Arturo Magidin
magidin-at-member-ams-org
If anyone can prove archimedian property of real numbers????? |
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| Aatu Koskensilta |
Posted: Mon Apr 14, 2008 10:11 am |
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On 2008-04-14, in sci.math, Student of Math wrote:
Quote: I use a new classification on sequences of 0s and 1s also,
my quastion is that if this assumption is independent from ZFC:
" Let A_n=[0,1/3^n] then the only number that is an element of all
of (A_n)s is 0=zero."
As said, it is trivially provable in ZF(C); that is, it is provable
that for every positive real r there is an n such that 1/(3^n) < r. It
remains completely obscure why you think this has anything to do with
the continuum hypothesis.
--
Aatu Koskensilta (aatu.koskensilta@xortec.fi)
"Wovon man nicht sprechen kann, daruber muss man schweigen"
- Ludwig Wittgenstein, Tractatus Logico-Philosophicus |
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| Arturo Magidin |
Posted: Mon Apr 14, 2008 10:28 am |
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In article <0abe5352-f6f1-441d-ad65-7368132ab74e@u36g2000prf.googlegroups.com>,
Student of Math <omar.hosseiny@gmail.com> wrote:
Quote: On Apr 14, 11:02=A0pm, magi...@math.berkeley.edu (Arturo Magidin) wrote:
In article <95521eae-e92a-483b-a8d0-13629b0d2...@x19g2000prg.googlegroups.=
com>,
Student of Math =A0<omar.hosse...@gmail.com> wrote:
On Apr 14, 6:41=3DA0pm, magi...@math.berkeley.edu (Arturo Magidin) wrote:=
=A0 =A0[...]
it is just =A0archimedian property of real numbers that i assume to
prove continuum hypothesis.
Can you please STATE the continuum hypothesis? I have the strong
suspicion that you cannot state it.
As you must know Archimedian property of real numbers is independent
from ZFC.
No, you are incorrect. The Archimedean property of the real numbers is
a THEOREM of ZFC.
What is true is that the Archimedean property is independent of the
field axioms (and of other axiomatic systems for algebra). However,
the fact that the REAL NUMBERS form an Archimedean field is a
perfectly fine theorem of ZF, it is NOT independent from ZF.
If anyone can prove archimedian property of real numbers?????
It follows from the supremum property, which is provable for the real
numbers.
The Archimedean property for real numbers states that for every e,M>0
there exists a natural number N such that Ne > M.
Fix M>0; let A be the set of all e>0 such that Ne<M for all natural
number N. We claim the set is empty (hence the Archimedean property
holds).
Note that if k>0 is not in A, then any f>k is also not in A: for if
k>0 is such that there exists a natural number N such that Nk>M, then
from f>k>0 we get Nf>Nk>M, hence f is also not in A. And note that M
is not in A.
Next, suppose by way of contradiction that A is not empty. Then A is a
nonempty set of real numbers, and is bounded above (by M, for
example), hence it has a supremum, or least upper bound. Call this
supremum s. Since A is nonempty, there is an e>0 in A, and s>=e, hence
s is positive.
Is s in A? Well, if s is in A, then for every natural number N we have
Ns<M. Then 2s is also in A, because for every natural number K, 2K is
a natural number, so K(2s) = (2K)s < M. Thus, 2s is in A. But 2>1 and
s>0, so 2s > 1s = s. Hence s, the least upper bound of A, is strictly
smaller than an element of A, which is contradiction. Thus, s cannot
be in A.
But then, consider (1/2)s. This is positive (since s is
positive). Since s is not in A, there exists a natural number N such
that Ns > M. But then 2N is a natural number, and 2N((1/2)s) = Ns>M,
hence (1/2)s is also not in N. Thus, (1/2)s is an upper bound of A,
but it is strictly smaller than the least upper bound of A (which is
s). Thus, we cannot have s not in A.
Thus, the assumption that A is nonempty leads to the absurd
proposition that its least upper bound is both in and not in A. Thus,
A must be empty. Therefore, for every e>0, e is not in A. Hence
there exists a natural number N such that Ne>M.
Thus, the real numbers satisfy the Archimedean Property.
(As for the Supremum Property for the real numbers, it follows for
example from the definition of real numbers as Dedekind Cuts; if A is
a set of real number, each real number x determined by a cut
{L_x|R_x}, and is bounded above by y={L_y|R_y}, then we can construct
the real number {L|R} whose left set L is the union of L_x for every x
in A; the fact that A is bounded above by y guarantees that this gives
you a Dedekind cut, and then it is a trivial matter to show that this
{L|R} is indeed the supremum of A).
--
======================================================================
"It's not denial. I'm just very selective about
what I accept as reality."
--- Calvin ("Calvin and Hobbes" by Bill Watterson)
======================================================================
Arturo Magidin
magidin-at-member-ams-org |
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| Aatu Koskensilta |
Posted: Mon Apr 14, 2008 10:43 am |
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On 2008-04-14, in sci.math, Student of Math wrote:
Quote: but relation "<" is not defined as an acxiom in ZF.
In saying that it is provable in ZF(C) that for every positive real r
there is an n such that 1/(3^n) < r we mean that the set theoretic
formalisation, ultimately in terms of the membership relation and the
usual logical notions, of that statement is provable ZF(C).
But let's set that aside and consider instead your "answer" to the
continuum hypothesis -- how does it go?
--
Aatu Koskensilta (aatu.koskensilta@xortec.fi)
"Wovon man nicht sprechen kann, daruber muss man schweigen"
- Ludwig Wittgenstein, Tractatus Logico-Philosophicus |
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| José Carlos Santos |
Posted: Mon Apr 14, 2008 12:38 pm |
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On 14-04-2008 16:34, Student of Math wrote:
Quote: I use a new classification on sequences of 0s and 1s also,
my quastion is that if this assumption is independent from ZFC:
" Let A_n=[0,1/3^n] then the only number that is an element of all
of (A_n)s is 0=zero."
As said, it is trivially provable in ZF(C); that is, it is provable
that for every positive real r there is an n such that 1/(3^n) < r. It
remains completely obscure why you think this has anything to do with
the continuum hypothesis.
--
Aatu Koskensilta (aatu.koskensi...@xortec.fi)
"Wovon man nicht sprechen kann, daruber muss man schweigen"
- Ludwig Wittgenstein, Tractatus Logico-Philosophicus
but relation "<" is not defined as an acxiom in ZF.
Well, "0" and "1" are not defined as an axiom in ZF either. Do you
deduce from that that the assertion "0 is different from 1" cannot be
proved in ZF?
Best regards,
Jose Carlos Santos |
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| Aatu Koskensilta |
Posted: Mon Apr 14, 2008 3:21 pm |
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On 2008-04-14, in sci.math, Student of Math wrote:
Quote: As you must know Archimedian property of real numbers is independent
from ZFC.
These strange assertions of yours appear to be purely random. Is there
some secret order, some subtle pattern, to them?
--
Aatu Koskensilta (aatu.koskensilta@xortec.fi)
"Wovon man nicht sprechen kann, daruber muss man schweigen"
- Ludwig Wittgenstein, Tractatus Logico-Philosophicus |
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| Aatu Koskensilta |
Posted: Mon Apr 14, 2008 3:23 pm |
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On 2008-04-14, in sci.math, Student of Math wrote:
Quote: If anyone can prove archimedian property of real numbers?????
Who knows? It's a mystery.
--
Aatu Koskensilta (aatu.koskensilta@xortec.fi)
"Wovon man nicht sprechen kann, daruber muss man schweigen"
- Ludwig Wittgenstein, Tractatus Logico-Philosophicus |
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| Student of Math |
Posted: Tue Apr 15, 2008 1:38 am |
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On Apr 14, 11:28 pm, magi...@math.berkeley.edu (Arturo Magidin) wrote:
Quote: In article <0abe5352-f6f1-441d-ad65-7368132ab...@u36g2000prf.googlegroups.com>,
Student of Math <omar.hosse...@gmail.com> wrote:
On Apr 14, 11:02=A0pm, magi...@math.berkeley.edu (Arturo Magidin) wrote:
In article <95521eae-e92a-483b-a8d0-13629b0d2...@x19g2000prg.googlegroups.> >com>,
Student of Math =A0<omar.hosse...@gmail.com> wrote:
On Apr 14, 6:41=3DA0pm, magi...@math.berkeley.edu (Arturo Magidin) wrote:
=A0 =A0[...]
it is just =A0archimedian property of real numbers that i assume to
prove continuum hypothesis.
Can you please STATE the continuum hypothesis? I have the strong
suspicion that you cannot state it.
As you must know Archimedian property of real numbers is independent
from ZFC.
No, you are incorrect. The Archimedean property of the real numbers is
a THEOREM of ZFC.
What is true is that the Archimedean property is independent of the
field axioms (and of other axiomatic systems for algebra). However,
the fact that the REAL NUMBERS form an Archimedean field is a
perfectly fine theorem of ZF, it is NOT independent from ZF.
If anyone can prove archimedian property of real numbers?????
It follows from the supremum property, which is provable for the real
numbers.
The Archimedean property for real numbers states that for every e,M>0
there exists a natural number N such that Ne > M.
Fix M>0; let A be the set of all e>0 such that Ne<M for all natural
number N. We claim the set is empty (hence the Archimedean property
holds).
Note that if k>0 is not in A, then any f>k is also not in A: for if
k>0 is such that there exists a natural number N such that Nk>M, then
from f>k>0 we get Nf>Nk>M, hence f is also not in A. And note that M
is not in A.
Next, suppose by way of contradiction that A is not empty. Then A is a
nonempty set of real numbers, and is bounded above (by M, for
example), hence it has a supremum, or least upper bound. Call this
supremum s. Since A is nonempty, there is an e>0 in A, and s>=e, hence
s is positive.
Is s in A? Well, if s is in A, then for every natural number N we have
Ns<M. Then 2s is also in A, because for every natural number K, 2K is
a natural number, so K(2s) = (2K)s < M. Thus, 2s is in A. But 2>1 and
s>0, so 2s > 1s = s. Hence s, the least upper bound of A, is strictly
smaller than an element of A, which is contradiction. Thus, s cannot
be in A.
But then, consider (1/2)s. This is positive (since s is
positive). Since s is not in A, there exists a natural number N such
that Ns > M. But then 2N is a natural number, and 2N((1/2)s) = Ns>M,
hence (1/2)s is also not in N. Thus, (1/2)s is an upper bound of A,
but it is strictly smaller than the least upper bound of A (which is
s). Thus, we cannot have s not in A.
Thus, the assumption that A is nonempty leads to the absurd
proposition that its least upper bound is both in and not in A. Thus,
A must be empty. Therefore, for every e>0, e is not in A. Hence
there exists a natural number N such that Ne>M.
Thus, the real numbers satisfy the Archimedean Property.
(As for the Supremum Property for the real numbers, it follows for
example from the definition of real numbers as Dedekind Cuts; if A is
a set of real number, each real number x determined by a cut
{L_x|R_x}, and is bounded above by y={L_y|R_y}, then we can construct
the real number {L|R} whose left set L is the union of L_x for every x
in A; the fact that A is bounded above by y guarantees that this gives
you a Dedekind cut, and then it is a trivial matter to show that this
{L|R} is indeed the supremum of A).
--
=====================================================================> "It's not denial. I'm just very selective about
what I accept as reality."
--- Calvin ("Calvin and Hobbes" by Bill Watterson)
=====================================================================
Arturo Magidin
magidin-at-member-ams-org- Hide quoted text -
- Show quoted text -
OK!
Where you have used ZF(C) in your proof? |
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| Arturo Magidin |
Posted: Tue Apr 15, 2008 4:00 am |
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In article <e05a3157-6fb1-4927-92ec-7a10f4a07ae7@b9g2000prh.googlegroups.com>,
Student of Math <omar.hosseiny@gmail.com> wrote:
[...]
Quote: Where you have used ZF(C) in your proof?
There are STANDARD constructions of R using Q, Q using Z, Z using N,
and N using ZF (no choice needed at any stage), which show that
everything I did can be done in ZF. For example, you can see all of
these constructions (as well as the definitions required) in "Proof
and Fundamentals: A First Course in Abstract Mathematics" by Ethan
D. Bloch, Birkhauser Publ, 2000, Chapter 8 (pp 323-362). You construct
the naturals by using the Axiom of infinity. You construct the
integers as a set of equivalence classes of pairs of natural
numbers. You construct the rationals as a set of equivalence classes
of the set of all pairs (a,b) with a and b integers, b nonzero. Then
you construct the real numbers as pairs (L,R), where L and R are sets
of rationals satisfying certain properties. All is done at the level
of sets.
Now, how about ->your<- alleged argument for the Continuum Hypothesis?
--
======================================================================
"It's not denial. I'm just very selective about
what I accept as reality."
--- Calvin ("Calvin and Hobbes" by Bill Watterson)
======================================================================
Arturo Magidin
magidin-at-member-ams-org |
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Posted: Tue Apr 15, 2008 5:43 am |
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On Apr 15, 7:38 am, Student of Math <omar.hosse...@gmail.com> wrote:
///\\\
Quote: OK!
Where you have used ZF(C) in your proof?
La con-grégation pour la doctrine de la foi mathématique
vous prie de montrer aux mathématiciens toute preuve
de CH ou de sa négation.
#Omega_7
$$$ |
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| Aatu Koskensilta |
Posted: Tue Apr 15, 2008 6:48 am |
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On 2008-04-15, in sci.math, Student of Math wrote:
Quote: Where you have used ZF(C) in your proof?
If you're interested in the details of formalising in ZF(C) proofs
such as Arturo gave you should consult a textbook on the subject. But
why not share with us your proof of the continuum hypothesis on the
assumption that 0 is the only real in [0, 1/(3^n)] for all n?
--
Aatu Koskensilta (aatu.koskensilta@xortec.fi)
"Wovon man nicht sprechen kann, daruber muss man schweigen"
- Ludwig Wittgenstein, Tractatus Logico-Philosophicus |
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| David C. Ullrich |
Posted: Tue Apr 15, 2008 7:16 am |
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On Mon, 14 Apr 2008 12:53:02 -0700 (PDT), Student of Math
<omar.hosseiny@gmail.com> wrote:
Quote: On Apr 14, 6:41 pm, magi...@math.berkeley.edu (Arturo Magidin) wrote:
In article <638f7745-efe8-4aae-803d-f198d783d...@b9g2000prh.googlegroups.com>,
Student of Math <omar.hosse...@gmail.com> wrote:
On Apr 14, 6:11=A0pm, Aatu Koskensilta <aatu.koskensi...@xortec.fi
wrote:
On 2008-04-14, in sci.math, Student of Math wrote:
I use a new classification on sequences of 0s and 1s also,
my quastion is that if this assumption is independent from ZFC:
" Let A_n=3D[0,1/3^n] then the only number that is an element of all
of (A_n)s is 0=3Dzero."
As said, it is trivially provable in ZF(C); that is, it is provable
that for every positive real r there is an n such that 1/(3^n) < r. It
remains completely obscure why you think this has anything to do with
the continuum hypothesis.
--
Aatu Koskensilta (aatu.koskensi...@xortec.fi)
"Wovon man nicht sprechen kann, daruber muss man schweigen"
=A0- Ludwig Wittgenstein, Tractatus Logico-Philosophicus
but relation "<" is not defined as an acxiom in ZF.
It does not have to be an axiom; it just needs to be expressible in
terms of ZF, and it can be.
For example, if you construct real numbers as Dedekind cuts of
rational numbers, then you can compare the real r={A|B} and the real
s={C|D}, by defining
r = s if and only if A=C.
r <= s if and only if A is a subset of C
r < s if and only if A is a subset of C and A=/=C.
Dedekind cuts are constructed from the rationals; the rationals and
their ordering (which is required to define Dedekind cuts) can be
defined in ZF using the integers and their order. The integers and
their order can be defined in ZF using the natural numbers and their
order. The natural numbers and their order can be defined in ZF using
the Axiom of Infinity and the relation "is an elemetn of". Thus, the
reals and their order "<" can be defined in ZF, using the axioms of
ZF.
So it matters not that "<" is not directly an axiom; it can be
expresse in ZF, and that is all you need.
--
======================================================================
"It's not denial. I'm just very selective about
what I accept as reality."
--- Calvin ("Calvin and Hobbes" by Bill Watterson)
======================================================================
Arturo Magidin
magidin-at-member-ams-org- Hide quoted text -
- Show quoted text -
it is just archimedian property of real numbers that i assume to
prove continuum hypothesis.
Really? How?
Quote: As you must know Archimedian property of real numbers is independent
from ZFC.
That's ridiculous.
Quote: Best regards,
Omar hosseiny
David C. Ullrich |
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| David C. Ullrich |
Posted: Tue Apr 15, 2008 7:18 am |
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On Mon, 14 Apr 2008 12:59:56 -0700 (PDT), Student of Math
<omar.hosseiny@gmail.com> wrote:
Quote: On Apr 14, 6:43 pm, Aatu Koskensilta <aatu.koskensi...@xortec.fi
wrote:
On 2008-04-14, in sci.math, Student of Math wrote:
but relation "<" is not defined as an acxiom in ZF.
In saying that it is provable in ZF(C) that for every positive real r
there is an n such that 1/(3^n) < r we mean that the set theoretic
formalisation, ultimately in terms of the membership relation and the
usual logical notions, of that statement is provable ZF(C).
But let's set that aside and consider instead your "answer" to the
continuum hypothesis -- how does it go?
--
Aatu Koskensilta (aatu.koskensi...@xortec.fi)
"Wovon man nicht sprechen kann, daruber muss man schweigen"
- Ludwig Wittgenstein, Tractatus Logico-Philosophicus
I have proved that any uncountable subset of real numbers has the
same
cardinality as that of the set of all of real numbers.
Yes, that's exactly what CH says.
_How_ do you prove this?
Quote: In fact I have proved that continuum and uncountable are equivalent
mathematical concepts.
Unfortunately _that_ is simply wrong. For example it's trivial
to prove that the set of all subsets of the reals has cardinality
strictly larger than c.
David C. Ullrich |
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