Hasse's classification of Quaternion algebras (over number fields)












2












$begingroup$


I am looking for the reference to Hasse's original publication classifying the Quaternion algebras over a number field $K$. The statement in the paper or book should read something like:



``Two Quaternion algebras over a number field $K$ are isomorphic iff they are ramified at the same number of places"










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$endgroup$








  • 2




    $begingroup$
    Ramification is for quaternion algebras over number fields, not over arbitrary fields?
    $endgroup$
    – Dietrich Burde
    Feb 1 at 15:11










  • $begingroup$
    oops corrected the question
    $endgroup$
    – Sam Hughes
    Feb 1 at 15:12






  • 3




    $begingroup$
    Theorem 4.8. here says:"Let $H$ and $H'$ be quaternion algebras over a number field $F$. Then $Hcong H'$ if and only if $Ram(H) = Ram(H')$.
    $endgroup$
    – Dietrich Burde
    Feb 1 at 15:15






  • 1




    $begingroup$
    It says $H_v = H otimes_K K_v$, or $H_v$ is a division algebra (and $v$ is said ramified) or $H_v cong M_2(K_v)$. Theorem 1.13 says it is about the equation $ax^2+by^2=1, (x,y) in K_v$ where $H=K[i,j], i^2=a,j^2=b,ij = -ji$
    $endgroup$
    – reuns
    Feb 1 at 22:17


















2












$begingroup$


I am looking for the reference to Hasse's original publication classifying the Quaternion algebras over a number field $K$. The statement in the paper or book should read something like:



``Two Quaternion algebras over a number field $K$ are isomorphic iff they are ramified at the same number of places"










share|cite|improve this question











$endgroup$








  • 2




    $begingroup$
    Ramification is for quaternion algebras over number fields, not over arbitrary fields?
    $endgroup$
    – Dietrich Burde
    Feb 1 at 15:11










  • $begingroup$
    oops corrected the question
    $endgroup$
    – Sam Hughes
    Feb 1 at 15:12






  • 3




    $begingroup$
    Theorem 4.8. here says:"Let $H$ and $H'$ be quaternion algebras over a number field $F$. Then $Hcong H'$ if and only if $Ram(H) = Ram(H')$.
    $endgroup$
    – Dietrich Burde
    Feb 1 at 15:15






  • 1




    $begingroup$
    It says $H_v = H otimes_K K_v$, or $H_v$ is a division algebra (and $v$ is said ramified) or $H_v cong M_2(K_v)$. Theorem 1.13 says it is about the equation $ax^2+by^2=1, (x,y) in K_v$ where $H=K[i,j], i^2=a,j^2=b,ij = -ji$
    $endgroup$
    – reuns
    Feb 1 at 22:17
















2












2








2





$begingroup$


I am looking for the reference to Hasse's original publication classifying the Quaternion algebras over a number field $K$. The statement in the paper or book should read something like:



``Two Quaternion algebras over a number field $K$ are isomorphic iff they are ramified at the same number of places"










share|cite|improve this question











$endgroup$




I am looking for the reference to Hasse's original publication classifying the Quaternion algebras over a number field $K$. The statement in the paper or book should read something like:



``Two Quaternion algebras over a number field $K$ are isomorphic iff they are ramified at the same number of places"







reference-request ring-theory algebraic-number-theory quaternions






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Feb 3 at 20:03







Sam Hughes

















asked Feb 1 at 14:47









Sam HughesSam Hughes

741114




741114








  • 2




    $begingroup$
    Ramification is for quaternion algebras over number fields, not over arbitrary fields?
    $endgroup$
    – Dietrich Burde
    Feb 1 at 15:11










  • $begingroup$
    oops corrected the question
    $endgroup$
    – Sam Hughes
    Feb 1 at 15:12






  • 3




    $begingroup$
    Theorem 4.8. here says:"Let $H$ and $H'$ be quaternion algebras over a number field $F$. Then $Hcong H'$ if and only if $Ram(H) = Ram(H')$.
    $endgroup$
    – Dietrich Burde
    Feb 1 at 15:15






  • 1




    $begingroup$
    It says $H_v = H otimes_K K_v$, or $H_v$ is a division algebra (and $v$ is said ramified) or $H_v cong M_2(K_v)$. Theorem 1.13 says it is about the equation $ax^2+by^2=1, (x,y) in K_v$ where $H=K[i,j], i^2=a,j^2=b,ij = -ji$
    $endgroup$
    – reuns
    Feb 1 at 22:17
















  • 2




    $begingroup$
    Ramification is for quaternion algebras over number fields, not over arbitrary fields?
    $endgroup$
    – Dietrich Burde
    Feb 1 at 15:11










  • $begingroup$
    oops corrected the question
    $endgroup$
    – Sam Hughes
    Feb 1 at 15:12






  • 3




    $begingroup$
    Theorem 4.8. here says:"Let $H$ and $H'$ be quaternion algebras over a number field $F$. Then $Hcong H'$ if and only if $Ram(H) = Ram(H')$.
    $endgroup$
    – Dietrich Burde
    Feb 1 at 15:15






  • 1




    $begingroup$
    It says $H_v = H otimes_K K_v$, or $H_v$ is a division algebra (and $v$ is said ramified) or $H_v cong M_2(K_v)$. Theorem 1.13 says it is about the equation $ax^2+by^2=1, (x,y) in K_v$ where $H=K[i,j], i^2=a,j^2=b,ij = -ji$
    $endgroup$
    – reuns
    Feb 1 at 22:17










2




2




$begingroup$
Ramification is for quaternion algebras over number fields, not over arbitrary fields?
$endgroup$
– Dietrich Burde
Feb 1 at 15:11




$begingroup$
Ramification is for quaternion algebras over number fields, not over arbitrary fields?
$endgroup$
– Dietrich Burde
Feb 1 at 15:11












$begingroup$
oops corrected the question
$endgroup$
– Sam Hughes
Feb 1 at 15:12




$begingroup$
oops corrected the question
$endgroup$
– Sam Hughes
Feb 1 at 15:12




3




3




$begingroup$
Theorem 4.8. here says:"Let $H$ and $H'$ be quaternion algebras over a number field $F$. Then $Hcong H'$ if and only if $Ram(H) = Ram(H')$.
$endgroup$
– Dietrich Burde
Feb 1 at 15:15




$begingroup$
Theorem 4.8. here says:"Let $H$ and $H'$ be quaternion algebras over a number field $F$. Then $Hcong H'$ if and only if $Ram(H) = Ram(H')$.
$endgroup$
– Dietrich Burde
Feb 1 at 15:15




1




1




$begingroup$
It says $H_v = H otimes_K K_v$, or $H_v$ is a division algebra (and $v$ is said ramified) or $H_v cong M_2(K_v)$. Theorem 1.13 says it is about the equation $ax^2+by^2=1, (x,y) in K_v$ where $H=K[i,j], i^2=a,j^2=b,ij = -ji$
$endgroup$
– reuns
Feb 1 at 22:17






$begingroup$
It says $H_v = H otimes_K K_v$, or $H_v$ is a division algebra (and $v$ is said ramified) or $H_v cong M_2(K_v)$. Theorem 1.13 says it is about the equation $ax^2+by^2=1, (x,y) in K_v$ where $H=K[i,j], i^2=a,j^2=b,ij = -ji$
$endgroup$
– reuns
Feb 1 at 22:17












1 Answer
1






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oldest

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1












$begingroup$

As detailed here, Hasse introduced an invariant, now known as the Hasse invariant in two papers (here and here) to classify central simple algebras.






share|cite|improve this answer









$endgroup$









  • 1




    $begingroup$
    In particular, for rank $4$ (quaternion algebras), the local invariant is either $0$ or $1/2$, the latter being the nonsplit (ramified) case. These local invariants must add up to $0pmod{Bbb Z}$. So to specify the isomorphism class it’s enough to specify which local invariants are $1/2$.
    $endgroup$
    – Lubin
    Feb 2 at 17:58












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1 Answer
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1 Answer
1






active

oldest

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active

oldest

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active

oldest

votes









1












$begingroup$

As detailed here, Hasse introduced an invariant, now known as the Hasse invariant in two papers (here and here) to classify central simple algebras.






share|cite|improve this answer









$endgroup$









  • 1




    $begingroup$
    In particular, for rank $4$ (quaternion algebras), the local invariant is either $0$ or $1/2$, the latter being the nonsplit (ramified) case. These local invariants must add up to $0pmod{Bbb Z}$. So to specify the isomorphism class it’s enough to specify which local invariants are $1/2$.
    $endgroup$
    – Lubin
    Feb 2 at 17:58
















1












$begingroup$

As detailed here, Hasse introduced an invariant, now known as the Hasse invariant in two papers (here and here) to classify central simple algebras.






share|cite|improve this answer









$endgroup$









  • 1




    $begingroup$
    In particular, for rank $4$ (quaternion algebras), the local invariant is either $0$ or $1/2$, the latter being the nonsplit (ramified) case. These local invariants must add up to $0pmod{Bbb Z}$. So to specify the isomorphism class it’s enough to specify which local invariants are $1/2$.
    $endgroup$
    – Lubin
    Feb 2 at 17:58














1












1








1





$begingroup$

As detailed here, Hasse introduced an invariant, now known as the Hasse invariant in two papers (here and here) to classify central simple algebras.






share|cite|improve this answer









$endgroup$



As detailed here, Hasse introduced an invariant, now known as the Hasse invariant in two papers (here and here) to classify central simple algebras.







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Feb 2 at 15:02









Sam HughesSam Hughes

741114




741114








  • 1




    $begingroup$
    In particular, for rank $4$ (quaternion algebras), the local invariant is either $0$ or $1/2$, the latter being the nonsplit (ramified) case. These local invariants must add up to $0pmod{Bbb Z}$. So to specify the isomorphism class it’s enough to specify which local invariants are $1/2$.
    $endgroup$
    – Lubin
    Feb 2 at 17:58














  • 1




    $begingroup$
    In particular, for rank $4$ (quaternion algebras), the local invariant is either $0$ or $1/2$, the latter being the nonsplit (ramified) case. These local invariants must add up to $0pmod{Bbb Z}$. So to specify the isomorphism class it’s enough to specify which local invariants are $1/2$.
    $endgroup$
    – Lubin
    Feb 2 at 17:58








1




1




$begingroup$
In particular, for rank $4$ (quaternion algebras), the local invariant is either $0$ or $1/2$, the latter being the nonsplit (ramified) case. These local invariants must add up to $0pmod{Bbb Z}$. So to specify the isomorphism class it’s enough to specify which local invariants are $1/2$.
$endgroup$
– Lubin
Feb 2 at 17:58




$begingroup$
In particular, for rank $4$ (quaternion algebras), the local invariant is either $0$ or $1/2$, the latter being the nonsplit (ramified) case. These local invariants must add up to $0pmod{Bbb Z}$. So to specify the isomorphism class it’s enough to specify which local invariants are $1/2$.
$endgroup$
– Lubin
Feb 2 at 17:58


















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