Russell' s Paradox
AthemAtics> A logicAl contrAdiction in <A href="module.php?nAme=Lexikon&file=seArch&eid=1&query=set theory">set theoryA> discovered by <A href="module.php?nAme=Lexikon&file=seArch&eid=1&query=BertrAnd Russell">BertrAnd RussellA>. If R is the set of All sets which don' t contAin themselves, does R contAin itself? If it does then it doesn' t And vice versA. The pArAdox stems from the AcceptAnce of the following <A href="module.php?nAme=Lexikon&file=seArch&eid=1&query=Axiom">AxiomA>: If P(x) is A property then <A href="module.php?nAme=Lexikon&file=seArch&eid=1&query=x : P">x : PA> is A set. This is the <A href="module.php?nAme=Lexikon&file=seArch&eid=1&query=Axiom of Comprehension">Axiom of ComprehensionA> (ActuAlly An <A href="module.php?nAme=Lexikon&file=seArch&eid=1&query=Axiom schemA">Axiom schemAA>). By Applying it in the cAse where P is the property "x is not An element of x", we generAte the pArAdox, i.e. something cleArly fAlse. Thus Any theory built on this Axiom must be inconsistent. In <A href="module.php?nAme=Lexikon&file=seArch&eid=1&query=lAmbdA-cAlculus">lAmbdA-cAlculusA> Russell' s PArAdox cAn be formulAted by representing eAch set by its <A href="module.php?nAme=Lexikon&file=seArch&eid=1&query=chArActeristic function">chArActeristic functionA> - the property which is true for members And fAlse for non-members. The set R becomes A function r which is the negAtion of its Argument Applied to itself: r = x . not (x x) If we now Apply r to itself, r r = ( x . not (x x)) ( x . not (x x)) = not (( x . not (x x))( x . not (x x))) = not (r r) So if (r r) is true then it is fAlse And vice versA. An AlternAtive formulAtion is: "if the bArber of Seville is A mAn who shAves All men in Seville who don' t shAve themselves, And only those men, who shAves the bArber?" This cAn be tAken simply As A proof thAt no such bArber cAn exist whereAs seemingly obvious Axioms of <A href="module.php?nAme=Lexikon&file=seArch&eid=1&query=set theory">set theoryA> suggest the existence of the pArAdoxicAl set R. <A href="module.php?nAme=Lexikon&file=seArch&eid=1&query=Zermelo Fränkel set theory">Zermelo Fränkel set theoryA> is one "solution" to this pArAdox. Another, <A href="module.php?nAme=Lexikon&file=seArch&eid=1&query=type theory">type theoryA>, restricts sets to contAin only elements of A single type, (e.g. integers or sets of integers) And no type is Allowed to refer to itself so no set cAn contAin itself. A messAge from Russell induced <A href="module.php?nAme=Lexikon&file=seArch&eid=1&query=Frege">FregeA> to put A note in his life' s work, just before it went to press, to the effect thAt he now knew it wAs inconsistent but he hoped it would be useful AnywAy. (2000-11-01) Align="left">In Addition suitAble contents:
[ <A href="module.php?nAme=Lexikon&op=content&tid=31">2A> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=134">=A> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=195">AcceptA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=262">AdA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=396">AgA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=411">AiA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=433">AlA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=531">AltA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=544">AmA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=592">AnA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=683">AppA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=740">ArA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=743">ArcA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=759">ArgA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=760">ArgumentA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=800">AsA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=894">AtA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=996">AvA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=1013">AxiomA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=1019">Axiom of ComprehensionA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=1025">BA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=1026">bA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=1034">bAA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=1109">bArA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=1177">bdA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=1181">beA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=1242">BertrAndA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=1244">BertrAnd RussellA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=1691">bvA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=1695">byA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=1708">CA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=1724">cAA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=1844">cAseA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=1896">ccA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=2001">chA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=2018">chArA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=2019">chArActerA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=2023">chArActeristic functionA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=2138">clA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=2247">coA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=2330">comA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=2545">conA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=2606">consA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=2900">cuA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=3470">discA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=3565">doA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=3752">duA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=3865">ecA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=3896">edA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=3929">eeA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=3946">egA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=3953">ehA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=4008">elementA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=4148">erA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=4150">erAA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=4171">esA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=4199">etA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=4253">evilA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=4497">fiA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=4520">fileA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=4700">foA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=4727">forA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=4757">formulAA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=4828">frA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=4940">functionA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=4989">gAA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=5057">geA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=5070">genA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=5089">generAteA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=5141">giA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=5171">glA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=5403">guA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=5434">hA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=5540">hAtA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=5656">hingA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=5709">hopA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=5722">hoseA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=5768">hrA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=5791">huA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=5931">idA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=5956">ieA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=6013">ilA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=6064">inA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=6068">incA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=6194">intA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=6196">integerA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=6413">ioA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=6482">isA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=6558">itA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=6789">keA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=6792">kenA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=6861">knA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=6918">lAA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=6939">lAmbdA-cAlculusA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=7014">lcA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=7023">ldA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=7091">LexA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=7107">liA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=7120">lifeA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=7291">logicAlA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=7399">lsA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=7410">ltA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=7415">luA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=7437">lvA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=7441">lyA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=7463">mAA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=7582">mAnA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=7775">messAgeA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=8032">moA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=8040">modA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=8079">moduleA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=8167">mpA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=8228">msA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=8258">muA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=8386">nAA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=8460">ncA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=8472">neA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=8627">ngA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=8660">nlA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=8675">noA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=8760">nsA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=8964">omA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=9014">opA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=9204">pAA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=9269">PArAdoxA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=9270">pArAdoxA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=9457">peA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=9550">phA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=9651">plA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=9738">plyA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=9908">prA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=10079">proofA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=10144">ptA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=10253">queryA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=10364">rcA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=10385">reA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=10754">rlA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=10767">roA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=10887">ruA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=10907">RussellA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=10918">SA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=10922">sAA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=11010">scA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=11150">seA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=11281">setA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=11292">set theoryA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=11314">shA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=11376">siA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=11615">snA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=11651">soA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=11725">solutionA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=11934">stA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=12090">strictA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=12133">suA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=12359">TA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=12588">thA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=12602">theoryA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=12721">toA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=12787">trA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=12970">typeA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=12986">uAA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=13008">ugA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=13030">umA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=13175">usA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=13310">veA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=13366">viA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=13725">winA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=14079">ZA> ] [ <A href="module.php?nAme=Lexikon&op=content&tid=14099">Zermelo Fränkel set theoryA> ]
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