What is the role of morphisms $A rightarrow mathbb{Z}$ in algebraic geometry?












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From Steve Awodey's Category Theory, p. 37:




Ring homomorphisms $A rightarrow mathbb{Z}$ into the initial ring $mathbb{Z}$ play an equally important role in algebraic geometry.




My question is thus, for someone who knows a reasonable amount of abstract algebra but zero algebraic geometry, what exactly is the role of such morphisms in algebraic geometry?










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  • $begingroup$
    The category of affine schemes is equivalent (and may even be defined as) $mathbf{CRing}^{op}$. This means that a commutative ring homomorphism $Atomathbb Z$ is a global element (i.e. an arrow from a terminal object) of $mathbf{Aff}$.
    $endgroup$
    – Derek Elkins
    Feb 2 at 8:52
















1












$begingroup$


From Steve Awodey's Category Theory, p. 37:




Ring homomorphisms $A rightarrow mathbb{Z}$ into the initial ring $mathbb{Z}$ play an equally important role in algebraic geometry.




My question is thus, for someone who knows a reasonable amount of abstract algebra but zero algebraic geometry, what exactly is the role of such morphisms in algebraic geometry?










share|cite|improve this question









$endgroup$












  • $begingroup$
    The category of affine schemes is equivalent (and may even be defined as) $mathbf{CRing}^{op}$. This means that a commutative ring homomorphism $Atomathbb Z$ is a global element (i.e. an arrow from a terminal object) of $mathbf{Aff}$.
    $endgroup$
    – Derek Elkins
    Feb 2 at 8:52














1












1








1





$begingroup$


From Steve Awodey's Category Theory, p. 37:




Ring homomorphisms $A rightarrow mathbb{Z}$ into the initial ring $mathbb{Z}$ play an equally important role in algebraic geometry.




My question is thus, for someone who knows a reasonable amount of abstract algebra but zero algebraic geometry, what exactly is the role of such morphisms in algebraic geometry?










share|cite|improve this question









$endgroup$




From Steve Awodey's Category Theory, p. 37:




Ring homomorphisms $A rightarrow mathbb{Z}$ into the initial ring $mathbb{Z}$ play an equally important role in algebraic geometry.




My question is thus, for someone who knows a reasonable amount of abstract algebra but zero algebraic geometry, what exactly is the role of such morphisms in algebraic geometry?







algebraic-geometry category-theory






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asked Feb 2 at 8:46









xuq01xuq01

1084




1084












  • $begingroup$
    The category of affine schemes is equivalent (and may even be defined as) $mathbf{CRing}^{op}$. This means that a commutative ring homomorphism $Atomathbb Z$ is a global element (i.e. an arrow from a terminal object) of $mathbf{Aff}$.
    $endgroup$
    – Derek Elkins
    Feb 2 at 8:52


















  • $begingroup$
    The category of affine schemes is equivalent (and may even be defined as) $mathbf{CRing}^{op}$. This means that a commutative ring homomorphism $Atomathbb Z$ is a global element (i.e. an arrow from a terminal object) of $mathbf{Aff}$.
    $endgroup$
    – Derek Elkins
    Feb 2 at 8:52
















$begingroup$
The category of affine schemes is equivalent (and may even be defined as) $mathbf{CRing}^{op}$. This means that a commutative ring homomorphism $Atomathbb Z$ is a global element (i.e. an arrow from a terminal object) of $mathbf{Aff}$.
$endgroup$
– Derek Elkins
Feb 2 at 8:52




$begingroup$
The category of affine schemes is equivalent (and may even be defined as) $mathbf{CRing}^{op}$. This means that a commutative ring homomorphism $Atomathbb Z$ is a global element (i.e. an arrow from a terminal object) of $mathbf{Aff}$.
$endgroup$
– Derek Elkins
Feb 2 at 8:52










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$begingroup$

These correspond to scheme maps $text{Spec},Bbb Ztotext{Spec},A$,
so to points of $text{Spec},A$ defined over $Bbb Z$.






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    1 Answer
    1






    active

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    active

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    3












    $begingroup$

    These correspond to scheme maps $text{Spec},Bbb Ztotext{Spec},A$,
    so to points of $text{Spec},A$ defined over $Bbb Z$.






    share|cite|improve this answer









    $endgroup$


















      3












      $begingroup$

      These correspond to scheme maps $text{Spec},Bbb Ztotext{Spec},A$,
      so to points of $text{Spec},A$ defined over $Bbb Z$.






      share|cite|improve this answer









      $endgroup$
















        3












        3








        3





        $begingroup$

        These correspond to scheme maps $text{Spec},Bbb Ztotext{Spec},A$,
        so to points of $text{Spec},A$ defined over $Bbb Z$.






        share|cite|improve this answer









        $endgroup$



        These correspond to scheme maps $text{Spec},Bbb Ztotext{Spec},A$,
        so to points of $text{Spec},A$ defined over $Bbb Z$.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Feb 2 at 8:51









        Lord Shark the UnknownLord Shark the Unknown

        108k1162136




        108k1162136






























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