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Topic: Zermelo Fraenkel set theory axiom system


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In the News (Sat 26 Dec 09)

  
  Axiomatic set theory - Wikipedia, the free encyclopedia
Initially controversial, set theory has come to play the role of a foundational theory in modern mathematics, in the sense of a theory invoked to justify assumptions made in mathematics concerning the existence of mathematical objects (such as numbers or functions) and their properties.
Set theory is a branch of mathematics created principally by the German mathematician Georg Cantor at the end of the 19th century.
Cantor's development of set theory was still "naive" in the sense that he did not have a precise axiomatization in mind.
en.wikipedia.org /wiki/Axiomatic_set_theory   (2764 words)

  
 Zermelo set theory - Wikipedia, the free encyclopedia
Zermelo set theory, as set out in an important paper in 1908 by Ernst Zermelo, is the ancestor of modern set theory.
Axiom of separation (Axiom der Aussonderung) "Whenever the propositional function –(x) is definite for all elements of a set M, M possesses a subset M'  containing as elements precisely those elements x of M for which –(x) is true".
The axiom of infinity is usually now modified to assert the existence of the first infinite von Neumann ordinal ω; it is interesting to observe that the original Zermelo axioms cannot prove the existence of this set, nor can the modified Zermelo axioms prove Zermelo's axiom of infinity.
en.wikipedia.org /wiki/Zermelo_set_theory   (1140 words)

  
 Zermelo-Fraenkel set theory
The Zermelo-Fraenkel axioms of set theory, denoted ZF, are the standard axioms of axiomatic set theory on which, together with the axiom of choice, all of ordinary mathematics is based.
The axioms are the result of work by Thoralf Skolem[?] in 1922, based on earlier work by Adolf Fraenkel[?] in the same year, which was based on the axiom system put forth by Ernst Zermelo in 1908 (Zermelo set theory[?]).
Axiom of union: For any set x, there is a set y such that the elements of y are precisely the elements of the elements of x.
www.ebroadcast.com.au /lookup/encyclopedia/ze/Zermelo-Fraenkel_axioms.html   (403 words)

  
 Continuum hypothesis
Georg Cantor introduced the concept of cardinality to compare the sizes of infinite sets, and he showed that the set of integer s is strictly smaller than the set of real number s.
If a set ''S was found that disproved the continuum hypothesis, it would be impossible to make a one-to-one correspondence between S and the set of integers, because there would always be elements of set S that were "left over".
GCH is also independent of the Zermelo-Fraenkel set theory axioms and it implies the axiom of choice.
www.nebulasearch.com /encyclopedia/article/Continuum_hypothesis.html   (963 words)

  
 Continuum hypothesis - Wikipedia
The continuum hypothesis is the hypothesis that there is no set whose cardinality is strictly between that of the integers and that of the real numbers.
As such it is not surprising that there should be statements which cannot be proven nor disproven within a given axiom system; in fact the content of Gödel's incompleteness theorem is that such statements always exist if the axiom system is strong enough and without contradictions.
The generalized continuum hypothesis (GCH) states that if a set's cardinality lies between that of an infinite set S and that of the power set of S, then it either has the same cardinality as the set S or the same cardinality as the power set of S: there are no in-betweens.
nostalgia.wikipedia.org /wiki/Continuum_hypothesis   (614 words)

  
 PlanetMath: axiom of choice
Thus objects that are proved to exist using the axiom of choice cannot generally be described by any kind of systematic rule, for if they could it would not be necessary to their construction.
In pure set theory, the axiom of choice is only relevant where most people's intuition more or less breaks down, when dealing with hierarchies of uncountable infinities.
Some mathematicians have suggested an axiom that would result in all subsets of the real numbers being measurable; this would of course imply the negation of the axiom of choice.
www.planetmath.org /encyclopedia/AxiomOfChoice.html   (723 words)

  
 Set Theory
Set Theory is the mathematical science of the infinite.
The language of set theory, in its simplicity, is sufficiently universal to formalize all mathematical concepts and thus set theory, along with Predicate Calculus, constitutes the true Foundations of Mathematics.
There are four main directions of current research in set theory, all intertwined and all aiming at the ultimate goal of the theory: to describe the structure of the mathematical universe.
plato.stanford.edu /entries/set-theory   (3279 words)

  
 Set theory
Bolzano gave examples to show that, unlike for finite sets, the elements of an infinite set could be put in 1-1 correspondence with elements of one of its proper subsets.
By this stage, however, set theory was beginning to have a major impact on other areas of mathematics.
Zermelo in 1908 was the first to attempt an axiomatisation of set theory.
www-groups.dcs.st-and.ac.uk /~history/HistTopics/Beginnings_of_set_theory.html   (2182 words)

  
 set theory intro   (Site not responding. Last check: 2007-10-31)
Set theory as a discipline of mathematical logic is deeply connected with other branches of mathematics, and such connections are what I mean by applications.
That is why modern set theory is deeply hinged on the study of large cardinals, in addition to the study of ZFC.
Another important topic in set theory are determinacy axioms and inner models, both of which are closely related to the study of large cardinals.
www.mth.uea.ac.uk /~h020/setintro.html   (467 words)

  
 Set Theory   (Site not responding. Last check: 2007-10-31)
The "cloud-capped V of infinitistic set theory" is the cumulative hierarchy of sets, starting traditionally with the empty set and built up (through systematic application of the axioms of set theory) to higher and higher orders of infinity.
First, the axioms for Zermelo-Fraenkel set theory with the axiom of choice and non-set "atoms" or ur-elements are shown in full, since the version accommodating ur-elements is not found in most set theory texts.
The set-theoretic axioms and axiom schemata for ZFC with ur-elements shown here follow [Jech 73], where G(pars) is an arbitrary first-order formula over a list pars of parameters p_1, p_2,..., p_n.
www.greenshade.com /sets.html   (849 words)

  
 Variants of Classical Set Theory and their Applications   (Site not responding. Last check: 2007-10-31)
Zermelo Fraenkel set theory with the Axiom of Choice, has been used, through much of this century, as the foundational theory for modern pure mathematics.
This is axiomatic set theory, modified by dropping the Axiom of Foundation and instead adding some of a variety of possible axioms that assert the existence of non-well-founded sets.
While the Axiom of Foundation is usually thought to be true for the standard iterative-combinatorial conception of set in which sets are thought of as being `formed' out of their elements, the axiom plays very little role in the coding of mathematical objects.
www.cs.man.ac.uk /~petera/LogicWeb/settheory.html   (509 words)

  
 Learn more about Continuum hypothesis in the online encyclopedia.   (Site not responding. Last check: 2007-10-31)
Georg Cantor introduced the concept of cardinality to compare the sizes of infinite sets, and he showed that the set of integers (naively: whole numbers) is strictly smaller than the set of real numbers (naively: infinite decimals) The continuum hypothesis states the following:
However, it turns out that the rational numbers can be placed in one-to-one correspondence with the integers, and therefore the set of rational numbers is the same size as the set of integers.
The generalized continuum hypothesis (GCH) states that if an infinite set's cardinality lies between that of an infinite set S and that of the power set of S, then it either has the same cardinality as the set S or the same cardinality as the power set of S: there are no in-betweens.
www.onlineencyclopedia.org /c/co/continuum_hypothesis.html   (1020 words)

  
 Zermelo-Fraenkel set theory Did You Mean zermelo-fraenkel set theory   (Site not responding. Last check: 2007-10-31)
The Zermelo-Fraenkel axioms of set theory together with the axiom of choice are the standard axioms of axiomatic set theory.
Axiom of pairing: If x, y are sets, then there exists a set containing x and y as its only elements, which we denote by {x,y} or {x} ?
Axiom of infinity: There exists a set x such that {} is in x and whenever y is in x, so is y ?
www.did-you-mean.com /Zermelo-Fraenkel_set_theory_3cdc.html   (572 words)

  
 Set Theory. Zermelo-Fraenkel Axioms. Russell's Paradox. Infinity. By K.Podnieks
Thus, the set theory C1+C1'+C21+C22+C23 seems to be equivalent (in the sense of Section 3.2) to PA (defined in Section 3.1).
The set theory adopting the axiom of extensionality (C1), the axiom C1', the separation axiom schema (C21), the pairing axiom (C22), the union axiom (C23), the power-set axiom (C24), the replacement axiom schema (C25), the axiom of infinity (C26) and the axiom of regularity (C3), is called Zermelo-Fraenkel set theory, and is denoted by ZF.
The set theory ZF+AC is denoted traditionally by ZFC.
www.ltn.lv /~podnieks/gt2.html   (8336 words)

  
 ZF Set Theory   (Site not responding. Last check: 2007-10-31)
Unfortunatly, this system was shown to be inconsistant because of Russell's paradox.
In this set theory, no loops can occur, there is no set of all sets that do not contain themselves, and the paradox is averted.
If x is a set, and there is a formula with two variables such that for every element of x, there is exactly one set which together with x makes the formula true, then there is a set of all sets which do so for some x.
www.wall.org /~aron/zf.html   (772 words)

  
 Bibliography: Set Theory with a Universal Set   (Site not responding. Last check: 2007-10-31)
This is a comprehensive bibliography on axiomatic set theories which have a universal set.
The equivalence of Quine's NF system to one of its fragments
Sheridan, K.J. The singleton function is a set in a slight extension of Church's set theory.
math.boisestate.edu /~holmes/holmes/setbiblio.html   (3932 words)

  
 Axiomatic Set Theory. Zermelo-Fraenkel Axioms
This theory is based on the intuitive concept of "a world of sets" where all sets (finite and infinite) and all their members exist simultaneously and completely.
The axioms C1 and C2[F] (for all formulas F that do not contain x) and the axiom of choice define a formal set theory C which corresponds almost 100% to Cantor's intuitive set theory (of the "pre-paradox" period of 1873-94).
The set theory adopting the axiom of extensionality (C1), the separation axiom schema (C21), the pairing axiom (C22), the union axiom (C23), the power-set axiom (C24), the replacement axiom schema (C25), the axiom of infinity (C26) and the axiom of regularity (C3), is called Zermelo-Fraenkel set theory, and is denoted by ZF.
linas.org /mirrors/www.ltn.lv/2001.03.27/~podnieks/gt2.html   (7448 words)

  
 Kipli's Cage -
A Steiner triple system (of degree `v`) is a collection of subsets of size 3 such that each pair of elements in `V` appears exactly once in an element of the collection.
Steiner triple systems show up in combinatorial design theory, an area of mathematics that aids in the design of statistical experiments (though, as is usual, many important mathematical concepts predate their application and go beyond the applications today).
The Axiom of Infinity I think I would like to introduce when we are focusing on the axioms of the natural numbers (since we can use that axiom to produce a model of the natural numbers).
kipliscage.powerblogs.com   (7728 words)

  
 Open Directory - Science: Math: Logic and Foundations: Set Theory   (Site not responding. Last check: 2007-10-31)
Consequences of the Axiom of Choice Project - Project to keep the book (also named in the title), describing forms related to the Axiom of Choice and their implications, updated.
This is a refinement of Russell's theory of types based on the observation that the types in Russell's theory look the same, as far as one can apparently prove.
Set Theory - Survey from the Stanford Encyclopedia of Philosophy by Thomas Jech.
dmoz.org /Science/Math/Logic_and_Foundations/Set_Theory   (517 words)

  
 Set theory   (Site not responding. Last check: 2007-10-31)
is a set of axiom  s and the rules of logic for deriving theorems from those axioms.
In set theory there is one primitive object, the empty set , and one relationship, set membership .
The integer two is the set containing 1 and the empty set.
www.mtnmath.com /book/node51.html   (192 words)

  
 Intuitionistic Zermelo-Fraenkel Set Theory in Coq
This development contains the set-as-pointed-graph interpretation of Intuitionistic Zermelo Fraenkel set theory in system F_omega.2++ (F_omega + one extra universe + intuitionistic choice operator), which is described in chapter 9 of the author's PhD thesis (for IZ) and in the author's CSL'03 paper (for the extension IZ -> IZF).
Intuitionistic Zermelo-Fraenkel set theory in Coq ================================================ These Coq-files contain the set-as-pointed graph interpretation of Intuitionistic Zermelo Fraenkel set theory in type theory, which is described in chapter 9 of the author's PhD thesis (for IZ) and in the author's CSL'03 paper (for the extension IZ -> IZF).
IZF_omega.v: Translation of the set-theoretic axiom of infinity.
pauillac.inria.fr /coq/contribs/IZF-in-coq.html   (207 words)

  
 [No title]
At the beginning of the 20th century mathematics a quest for the foundations of mathematics was pursued by Cantor, Hilbert, Russell and others… Finally, Zermelo managed to formalize mathematics by inventing an axiomatic system.
However, Fraenkel and Skolem resolved these problems in the 1920’s.
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www.unr.edu /Math/UpperDivision/AxiomaticSetTheory.doc   (289 words)

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