Was there ever an axiom rendered a theorem?How can the axiom of choice be called “axiom” if it is false in Cohen's model?What is the difference between an axiom and a postulate?Why is Zorn's Lemma called a lemma?Can a sequence whose final term is an axiom, be considered a formal proof?Axiom Systems and Formal SystemsWhen the mathematical community consider the inclusion of a new axiom?.A Concept Which Has Been 'Specialized' In the Course of HistoryWhy is the Generalization Axiom considered a Pure Axiom?Euclid's Elements missing axiom of M. Pasch examplesZermelo-Fraenkel set theory and Hilbert's axioms for geometryWhich is the first theorem in Euclid's Elements which uses Pasch's Axiom?Axiom of Choice — Why is it an axiom and not a theorem?Is consistency an axiom of mathematics?Redunduncy of Pasch's Axiom of Hilbert's Foundations of Geometry

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Was there ever an axiom rendered a theorem?


How can the axiom of choice be called “axiom” if it is false in Cohen's model?What is the difference between an axiom and a postulate?Why is Zorn's Lemma called a lemma?Can a sequence whose final term is an axiom, be considered a formal proof?Axiom Systems and Formal SystemsWhen the mathematical community consider the inclusion of a new axiom?.A Concept Which Has Been 'Specialized' In the Course of HistoryWhy is the Generalization Axiom considered a Pure Axiom?Euclid's Elements missing axiom of M. Pasch examplesZermelo-Fraenkel set theory and Hilbert's axioms for geometryWhich is the first theorem in Euclid's Elements which uses Pasch's Axiom?Axiom of Choice — Why is it an axiom and not a theorem?Is consistency an axiom of mathematics?Redunduncy of Pasch's Axiom of Hilbert's Foundations of Geometry













7












$begingroup$


In the history of mathematics, are there notable examples of theorems which have been first considered axioms?



Alternatively, was there any statement first considered an axiom that later have been shown to be derived from other axiom(s), therefore rendering the statement a theorem?










share|cite|improve this question









New contributor




Eyal Roth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$







  • 2




    $begingroup$
    All axioms are theorems, math.stackexchange.com/questions/1242021/… also of interest might be math.stackexchange.com/questions/258346/… and math.stackexchange.com/questions/1383457/… and math.stackexchange.com/questions/1131748/… might also be relevant.
    $endgroup$
    – Asaf Karagila
    7 hours ago






  • 1




    $begingroup$
    Eyal, the main point here is that "axiom" is a social agreement, rather than a mathematical definition.
    $endgroup$
    – Asaf Karagila
    6 hours ago






  • 4




    $begingroup$
    And indeed the Axiom of Choice is taken as an axiom and is reduced to a Theorem when assuming ZF+ZL, or or even to a false statement when assuming ZF+AD.
    $endgroup$
    – Asaf Karagila
    6 hours ago






  • 1




    $begingroup$
    I believe all the the axioms from Peano Arithmetic (PA) can be derived from ZF?
    $endgroup$
    – Bram28
    4 hours ago






  • 1




    $begingroup$
    @CliveNewstead: The axiom of infinity is ill-defined if you have not yet defined the empty set (because the empty set symbol appears in the axiom of infinity).
    $endgroup$
    – Kevin
    3 hours ago















7












$begingroup$


In the history of mathematics, are there notable examples of theorems which have been first considered axioms?



Alternatively, was there any statement first considered an axiom that later have been shown to be derived from other axiom(s), therefore rendering the statement a theorem?










share|cite|improve this question









New contributor




Eyal Roth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$







  • 2




    $begingroup$
    All axioms are theorems, math.stackexchange.com/questions/1242021/… also of interest might be math.stackexchange.com/questions/258346/… and math.stackexchange.com/questions/1383457/… and math.stackexchange.com/questions/1131748/… might also be relevant.
    $endgroup$
    – Asaf Karagila
    7 hours ago






  • 1




    $begingroup$
    Eyal, the main point here is that "axiom" is a social agreement, rather than a mathematical definition.
    $endgroup$
    – Asaf Karagila
    6 hours ago






  • 4




    $begingroup$
    And indeed the Axiom of Choice is taken as an axiom and is reduced to a Theorem when assuming ZF+ZL, or or even to a false statement when assuming ZF+AD.
    $endgroup$
    – Asaf Karagila
    6 hours ago






  • 1




    $begingroup$
    I believe all the the axioms from Peano Arithmetic (PA) can be derived from ZF?
    $endgroup$
    – Bram28
    4 hours ago






  • 1




    $begingroup$
    @CliveNewstead: The axiom of infinity is ill-defined if you have not yet defined the empty set (because the empty set symbol appears in the axiom of infinity).
    $endgroup$
    – Kevin
    3 hours ago













7












7








7





$begingroup$


In the history of mathematics, are there notable examples of theorems which have been first considered axioms?



Alternatively, was there any statement first considered an axiom that later have been shown to be derived from other axiom(s), therefore rendering the statement a theorem?










share|cite|improve this question









New contributor




Eyal Roth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$




In the history of mathematics, are there notable examples of theorems which have been first considered axioms?



Alternatively, was there any statement first considered an axiom that later have been shown to be derived from other axiom(s), therefore rendering the statement a theorem?







logic math-history axioms






share|cite|improve this question









New contributor




Eyal Roth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|cite|improve this question









New contributor




Eyal Roth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|cite|improve this question




share|cite|improve this question








edited 6 hours ago







Eyal Roth













New contributor




Eyal Roth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









asked 7 hours ago









Eyal RothEyal Roth

1443




1443




New contributor




Eyal Roth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





New contributor





Eyal Roth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Eyal Roth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







  • 2




    $begingroup$
    All axioms are theorems, math.stackexchange.com/questions/1242021/… also of interest might be math.stackexchange.com/questions/258346/… and math.stackexchange.com/questions/1383457/… and math.stackexchange.com/questions/1131748/… might also be relevant.
    $endgroup$
    – Asaf Karagila
    7 hours ago






  • 1




    $begingroup$
    Eyal, the main point here is that "axiom" is a social agreement, rather than a mathematical definition.
    $endgroup$
    – Asaf Karagila
    6 hours ago






  • 4




    $begingroup$
    And indeed the Axiom of Choice is taken as an axiom and is reduced to a Theorem when assuming ZF+ZL, or or even to a false statement when assuming ZF+AD.
    $endgroup$
    – Asaf Karagila
    6 hours ago






  • 1




    $begingroup$
    I believe all the the axioms from Peano Arithmetic (PA) can be derived from ZF?
    $endgroup$
    – Bram28
    4 hours ago






  • 1




    $begingroup$
    @CliveNewstead: The axiom of infinity is ill-defined if you have not yet defined the empty set (because the empty set symbol appears in the axiom of infinity).
    $endgroup$
    – Kevin
    3 hours ago












  • 2




    $begingroup$
    All axioms are theorems, math.stackexchange.com/questions/1242021/… also of interest might be math.stackexchange.com/questions/258346/… and math.stackexchange.com/questions/1383457/… and math.stackexchange.com/questions/1131748/… might also be relevant.
    $endgroup$
    – Asaf Karagila
    7 hours ago






  • 1




    $begingroup$
    Eyal, the main point here is that "axiom" is a social agreement, rather than a mathematical definition.
    $endgroup$
    – Asaf Karagila
    6 hours ago






  • 4




    $begingroup$
    And indeed the Axiom of Choice is taken as an axiom and is reduced to a Theorem when assuming ZF+ZL, or or even to a false statement when assuming ZF+AD.
    $endgroup$
    – Asaf Karagila
    6 hours ago






  • 1




    $begingroup$
    I believe all the the axioms from Peano Arithmetic (PA) can be derived from ZF?
    $endgroup$
    – Bram28
    4 hours ago






  • 1




    $begingroup$
    @CliveNewstead: The axiom of infinity is ill-defined if you have not yet defined the empty set (because the empty set symbol appears in the axiom of infinity).
    $endgroup$
    – Kevin
    3 hours ago







2




2




$begingroup$
All axioms are theorems, math.stackexchange.com/questions/1242021/… also of interest might be math.stackexchange.com/questions/258346/… and math.stackexchange.com/questions/1383457/… and math.stackexchange.com/questions/1131748/… might also be relevant.
$endgroup$
– Asaf Karagila
7 hours ago




$begingroup$
All axioms are theorems, math.stackexchange.com/questions/1242021/… also of interest might be math.stackexchange.com/questions/258346/… and math.stackexchange.com/questions/1383457/… and math.stackexchange.com/questions/1131748/… might also be relevant.
$endgroup$
– Asaf Karagila
7 hours ago




1




1




$begingroup$
Eyal, the main point here is that "axiom" is a social agreement, rather than a mathematical definition.
$endgroup$
– Asaf Karagila
6 hours ago




$begingroup$
Eyal, the main point here is that "axiom" is a social agreement, rather than a mathematical definition.
$endgroup$
– Asaf Karagila
6 hours ago




4




4




$begingroup$
And indeed the Axiom of Choice is taken as an axiom and is reduced to a Theorem when assuming ZF+ZL, or or even to a false statement when assuming ZF+AD.
$endgroup$
– Asaf Karagila
6 hours ago




$begingroup$
And indeed the Axiom of Choice is taken as an axiom and is reduced to a Theorem when assuming ZF+ZL, or or even to a false statement when assuming ZF+AD.
$endgroup$
– Asaf Karagila
6 hours ago




1




1




$begingroup$
I believe all the the axioms from Peano Arithmetic (PA) can be derived from ZF?
$endgroup$
– Bram28
4 hours ago




$begingroup$
I believe all the the axioms from Peano Arithmetic (PA) can be derived from ZF?
$endgroup$
– Bram28
4 hours ago




1




1




$begingroup$
@CliveNewstead: The axiom of infinity is ill-defined if you have not yet defined the empty set (because the empty set symbol appears in the axiom of infinity).
$endgroup$
– Kevin
3 hours ago




$begingroup$
@CliveNewstead: The axiom of infinity is ill-defined if you have not yet defined the empty set (because the empty set symbol appears in the axiom of infinity).
$endgroup$
– Kevin
3 hours ago










3 Answers
3






active

oldest

votes


















5












$begingroup$

Fraenkel introduced the axiom schema of replacement to set theory. This implied the axiom schema of comprehension, and allowed the empty set and unordered pair axioms to follow from the axiom of infinity. (Note Zermelo set theory includes the axiom of choice whereas ZF does not, so Zermelo+replacement is ZFC.) The "deleted" axioms are typically listed when describing ZF(C), partly so people realise they're in Zermelo set theory, partly for easier comparisons with other set theories of interest.






share|cite|improve this answer









$endgroup$




















    4












    $begingroup$

    Yes, everywhere. What is an axiom from one theory can be a theorem in another.



    Euclid's fifth postulate can be replaced by the statement that the angles on the inside of each triangle add up to $pi$ radians.



    Another notable example is the axiom of choice, which is equivalent in some axiomatic systems to Zorn's Lemma.



    Also, watch this Feynman clip.






    share|cite|improve this answer











    $endgroup$












    • $begingroup$
      That is an interesting clip (and I love the accent). If I understand correctly, Feynman discusses axioms which have bi-directional relations; i.e, one can be deduced from the other and vice-versa; or perhaps, any two of three axioms can imply the third. I'm rather interested in cases of uni-directional axioms which have been discovered to be implied from another axiom or set of axioms.
      $endgroup$
      – Eyal Roth
      6 hours ago






    • 1




      $begingroup$
      These cases are considered to be alternative statements of the same axiom. You choose whichever one you want as an axiom and prove the other. If you have an axiom you suspect is redundant you might find a way to prove one of the statements, or you might find a statement that is obvious enough that people accept it as an axiom. In both of these cases, the axiom has been proven to be independent of the others. I think OP wants a case where a statement was thought to be independent of the other axioms of a subject and was shown to be a consequence of them.
      $endgroup$
      – Ross Millikan
      41 mins ago


















    4












    $begingroup$

    The most famous example I know is that of Hilbert's axiom II.4 for the linear ordering of points on a line, for Euclidean geometry, proven to be superfluous by E.H. Moore. See this wikipedia article, especially "Hilbert's discarded axiom". https://en.wikipedia.org/wiki/Hilbert%27s_axioms



    In the article of Moore linked there, it is stated that also axiom I.4 is superfluous.



    http://www.ams.org/journals/tran/1902-003-01/S0002-9947-1902-1500592-8/S0002-9947-1902-1500592-8.pdf






    share|cite|improve this answer









    $endgroup$













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      3 Answers
      3






      active

      oldest

      votes








      3 Answers
      3






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      5












      $begingroup$

      Fraenkel introduced the axiom schema of replacement to set theory. This implied the axiom schema of comprehension, and allowed the empty set and unordered pair axioms to follow from the axiom of infinity. (Note Zermelo set theory includes the axiom of choice whereas ZF does not, so Zermelo+replacement is ZFC.) The "deleted" axioms are typically listed when describing ZF(C), partly so people realise they're in Zermelo set theory, partly for easier comparisons with other set theories of interest.






      share|cite|improve this answer









      $endgroup$

















        5












        $begingroup$

        Fraenkel introduced the axiom schema of replacement to set theory. This implied the axiom schema of comprehension, and allowed the empty set and unordered pair axioms to follow from the axiom of infinity. (Note Zermelo set theory includes the axiom of choice whereas ZF does not, so Zermelo+replacement is ZFC.) The "deleted" axioms are typically listed when describing ZF(C), partly so people realise they're in Zermelo set theory, partly for easier comparisons with other set theories of interest.






        share|cite|improve this answer









        $endgroup$















          5












          5








          5





          $begingroup$

          Fraenkel introduced the axiom schema of replacement to set theory. This implied the axiom schema of comprehension, and allowed the empty set and unordered pair axioms to follow from the axiom of infinity. (Note Zermelo set theory includes the axiom of choice whereas ZF does not, so Zermelo+replacement is ZFC.) The "deleted" axioms are typically listed when describing ZF(C), partly so people realise they're in Zermelo set theory, partly for easier comparisons with other set theories of interest.






          share|cite|improve this answer









          $endgroup$



          Fraenkel introduced the axiom schema of replacement to set theory. This implied the axiom schema of comprehension, and allowed the empty set and unordered pair axioms to follow from the axiom of infinity. (Note Zermelo set theory includes the axiom of choice whereas ZF does not, so Zermelo+replacement is ZFC.) The "deleted" axioms are typically listed when describing ZF(C), partly so people realise they're in Zermelo set theory, partly for easier comparisons with other set theories of interest.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered 6 hours ago









          J.G.J.G.

          33k23251




          33k23251





















              4












              $begingroup$

              Yes, everywhere. What is an axiom from one theory can be a theorem in another.



              Euclid's fifth postulate can be replaced by the statement that the angles on the inside of each triangle add up to $pi$ radians.



              Another notable example is the axiom of choice, which is equivalent in some axiomatic systems to Zorn's Lemma.



              Also, watch this Feynman clip.






              share|cite|improve this answer











              $endgroup$












              • $begingroup$
                That is an interesting clip (and I love the accent). If I understand correctly, Feynman discusses axioms which have bi-directional relations; i.e, one can be deduced from the other and vice-versa; or perhaps, any two of three axioms can imply the third. I'm rather interested in cases of uni-directional axioms which have been discovered to be implied from another axiom or set of axioms.
                $endgroup$
                – Eyal Roth
                6 hours ago






              • 1




                $begingroup$
                These cases are considered to be alternative statements of the same axiom. You choose whichever one you want as an axiom and prove the other. If you have an axiom you suspect is redundant you might find a way to prove one of the statements, or you might find a statement that is obvious enough that people accept it as an axiom. In both of these cases, the axiom has been proven to be independent of the others. I think OP wants a case where a statement was thought to be independent of the other axioms of a subject and was shown to be a consequence of them.
                $endgroup$
                – Ross Millikan
                41 mins ago















              4












              $begingroup$

              Yes, everywhere. What is an axiom from one theory can be a theorem in another.



              Euclid's fifth postulate can be replaced by the statement that the angles on the inside of each triangle add up to $pi$ radians.



              Another notable example is the axiom of choice, which is equivalent in some axiomatic systems to Zorn's Lemma.



              Also, watch this Feynman clip.






              share|cite|improve this answer











              $endgroup$












              • $begingroup$
                That is an interesting clip (and I love the accent). If I understand correctly, Feynman discusses axioms which have bi-directional relations; i.e, one can be deduced from the other and vice-versa; or perhaps, any two of three axioms can imply the third. I'm rather interested in cases of uni-directional axioms which have been discovered to be implied from another axiom or set of axioms.
                $endgroup$
                – Eyal Roth
                6 hours ago






              • 1




                $begingroup$
                These cases are considered to be alternative statements of the same axiom. You choose whichever one you want as an axiom and prove the other. If you have an axiom you suspect is redundant you might find a way to prove one of the statements, or you might find a statement that is obvious enough that people accept it as an axiom. In both of these cases, the axiom has been proven to be independent of the others. I think OP wants a case where a statement was thought to be independent of the other axioms of a subject and was shown to be a consequence of them.
                $endgroup$
                – Ross Millikan
                41 mins ago













              4












              4








              4





              $begingroup$

              Yes, everywhere. What is an axiom from one theory can be a theorem in another.



              Euclid's fifth postulate can be replaced by the statement that the angles on the inside of each triangle add up to $pi$ radians.



              Another notable example is the axiom of choice, which is equivalent in some axiomatic systems to Zorn's Lemma.



              Also, watch this Feynman clip.






              share|cite|improve this answer











              $endgroup$



              Yes, everywhere. What is an axiom from one theory can be a theorem in another.



              Euclid's fifth postulate can be replaced by the statement that the angles on the inside of each triangle add up to $pi$ radians.



              Another notable example is the axiom of choice, which is equivalent in some axiomatic systems to Zorn's Lemma.



              Also, watch this Feynman clip.







              share|cite|improve this answer














              share|cite|improve this answer



              share|cite|improve this answer








              edited 7 hours ago


























              community wiki





              2 revs
              Shaun












              • $begingroup$
                That is an interesting clip (and I love the accent). If I understand correctly, Feynman discusses axioms which have bi-directional relations; i.e, one can be deduced from the other and vice-versa; or perhaps, any two of three axioms can imply the third. I'm rather interested in cases of uni-directional axioms which have been discovered to be implied from another axiom or set of axioms.
                $endgroup$
                – Eyal Roth
                6 hours ago






              • 1




                $begingroup$
                These cases are considered to be alternative statements of the same axiom. You choose whichever one you want as an axiom and prove the other. If you have an axiom you suspect is redundant you might find a way to prove one of the statements, or you might find a statement that is obvious enough that people accept it as an axiom. In both of these cases, the axiom has been proven to be independent of the others. I think OP wants a case where a statement was thought to be independent of the other axioms of a subject and was shown to be a consequence of them.
                $endgroup$
                – Ross Millikan
                41 mins ago
















              • $begingroup$
                That is an interesting clip (and I love the accent). If I understand correctly, Feynman discusses axioms which have bi-directional relations; i.e, one can be deduced from the other and vice-versa; or perhaps, any two of three axioms can imply the third. I'm rather interested in cases of uni-directional axioms which have been discovered to be implied from another axiom or set of axioms.
                $endgroup$
                – Eyal Roth
                6 hours ago






              • 1




                $begingroup$
                These cases are considered to be alternative statements of the same axiom. You choose whichever one you want as an axiom and prove the other. If you have an axiom you suspect is redundant you might find a way to prove one of the statements, or you might find a statement that is obvious enough that people accept it as an axiom. In both of these cases, the axiom has been proven to be independent of the others. I think OP wants a case where a statement was thought to be independent of the other axioms of a subject and was shown to be a consequence of them.
                $endgroup$
                – Ross Millikan
                41 mins ago















              $begingroup$
              That is an interesting clip (and I love the accent). If I understand correctly, Feynman discusses axioms which have bi-directional relations; i.e, one can be deduced from the other and vice-versa; or perhaps, any two of three axioms can imply the third. I'm rather interested in cases of uni-directional axioms which have been discovered to be implied from another axiom or set of axioms.
              $endgroup$
              – Eyal Roth
              6 hours ago




              $begingroup$
              That is an interesting clip (and I love the accent). If I understand correctly, Feynman discusses axioms which have bi-directional relations; i.e, one can be deduced from the other and vice-versa; or perhaps, any two of three axioms can imply the third. I'm rather interested in cases of uni-directional axioms which have been discovered to be implied from another axiom or set of axioms.
              $endgroup$
              – Eyal Roth
              6 hours ago




              1




              1




              $begingroup$
              These cases are considered to be alternative statements of the same axiom. You choose whichever one you want as an axiom and prove the other. If you have an axiom you suspect is redundant you might find a way to prove one of the statements, or you might find a statement that is obvious enough that people accept it as an axiom. In both of these cases, the axiom has been proven to be independent of the others. I think OP wants a case where a statement was thought to be independent of the other axioms of a subject and was shown to be a consequence of them.
              $endgroup$
              – Ross Millikan
              41 mins ago




              $begingroup$
              These cases are considered to be alternative statements of the same axiom. You choose whichever one you want as an axiom and prove the other. If you have an axiom you suspect is redundant you might find a way to prove one of the statements, or you might find a statement that is obvious enough that people accept it as an axiom. In both of these cases, the axiom has been proven to be independent of the others. I think OP wants a case where a statement was thought to be independent of the other axioms of a subject and was shown to be a consequence of them.
              $endgroup$
              – Ross Millikan
              41 mins ago











              4












              $begingroup$

              The most famous example I know is that of Hilbert's axiom II.4 for the linear ordering of points on a line, for Euclidean geometry, proven to be superfluous by E.H. Moore. See this wikipedia article, especially "Hilbert's discarded axiom". https://en.wikipedia.org/wiki/Hilbert%27s_axioms



              In the article of Moore linked there, it is stated that also axiom I.4 is superfluous.



              http://www.ams.org/journals/tran/1902-003-01/S0002-9947-1902-1500592-8/S0002-9947-1902-1500592-8.pdf






              share|cite|improve this answer









              $endgroup$

















                4












                $begingroup$

                The most famous example I know is that of Hilbert's axiom II.4 for the linear ordering of points on a line, for Euclidean geometry, proven to be superfluous by E.H. Moore. See this wikipedia article, especially "Hilbert's discarded axiom". https://en.wikipedia.org/wiki/Hilbert%27s_axioms



                In the article of Moore linked there, it is stated that also axiom I.4 is superfluous.



                http://www.ams.org/journals/tran/1902-003-01/S0002-9947-1902-1500592-8/S0002-9947-1902-1500592-8.pdf






                share|cite|improve this answer









                $endgroup$















                  4












                  4








                  4





                  $begingroup$

                  The most famous example I know is that of Hilbert's axiom II.4 for the linear ordering of points on a line, for Euclidean geometry, proven to be superfluous by E.H. Moore. See this wikipedia article, especially "Hilbert's discarded axiom". https://en.wikipedia.org/wiki/Hilbert%27s_axioms



                  In the article of Moore linked there, it is stated that also axiom I.4 is superfluous.



                  http://www.ams.org/journals/tran/1902-003-01/S0002-9947-1902-1500592-8/S0002-9947-1902-1500592-8.pdf






                  share|cite|improve this answer









                  $endgroup$



                  The most famous example I know is that of Hilbert's axiom II.4 for the linear ordering of points on a line, for Euclidean geometry, proven to be superfluous by E.H. Moore. See this wikipedia article, especially "Hilbert's discarded axiom". https://en.wikipedia.org/wiki/Hilbert%27s_axioms



                  In the article of Moore linked there, it is stated that also axiom I.4 is superfluous.



                  http://www.ams.org/journals/tran/1902-003-01/S0002-9947-1902-1500592-8/S0002-9947-1902-1500592-8.pdf







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered 2 hours ago









                  roy smithroy smith

                  959711




                  959711




















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