Proving surjectivity of Hopf map and existence of Hopf Circles on $mathbb{S}^3$












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$begingroup$


I am using the Hopf Map $f: mathbb{S}^3 rightarrow mathbb{S}^2$ where $f(a,b,c,d) = (2(ab+cd),2(ad-cb),(a^2+c^2)-(b^2+d^2))$



My question is



1.) How can I prove surjectivity of the map? I am aware of the primary definition of surjectivity but I am unsure how to apply in this case.



I tried using the trivial method of finding an inverse but the method is very complicated.



2.) How can I show that a point that the preimage of $q in mathbb{S}^2$ is a circle in $mathbb{S}^3$?



I realize that the solution is dependent on finding the inverse function as hinted in the first part, but since the function itself was complicated to find, hence I had no progress in this part.










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$endgroup$












  • $begingroup$
    It might be helpful to view the two-sphere and three-sphere in slighty different ways: we can view the two-sphere as $mathbb{C}P^1$, and the three-sphere as the elements in $mathbb{C}^2$ of magnitude 1. Then the Hopf map is given by $(z,w) mapsto [z:w]$.
    $endgroup$
    – Brian Shin
    Nov 26 '18 at 0:57












  • $begingroup$
    @BrianShin How can I demonstrate the equivalence of the two maps?
    $endgroup$
    – mathnoob123
    Nov 26 '18 at 8:09
















0












$begingroup$


I am using the Hopf Map $f: mathbb{S}^3 rightarrow mathbb{S}^2$ where $f(a,b,c,d) = (2(ab+cd),2(ad-cb),(a^2+c^2)-(b^2+d^2))$



My question is



1.) How can I prove surjectivity of the map? I am aware of the primary definition of surjectivity but I am unsure how to apply in this case.



I tried using the trivial method of finding an inverse but the method is very complicated.



2.) How can I show that a point that the preimage of $q in mathbb{S}^2$ is a circle in $mathbb{S}^3$?



I realize that the solution is dependent on finding the inverse function as hinted in the first part, but since the function itself was complicated to find, hence I had no progress in this part.










share|cite|improve this question











$endgroup$












  • $begingroup$
    It might be helpful to view the two-sphere and three-sphere in slighty different ways: we can view the two-sphere as $mathbb{C}P^1$, and the three-sphere as the elements in $mathbb{C}^2$ of magnitude 1. Then the Hopf map is given by $(z,w) mapsto [z:w]$.
    $endgroup$
    – Brian Shin
    Nov 26 '18 at 0:57












  • $begingroup$
    @BrianShin How can I demonstrate the equivalence of the two maps?
    $endgroup$
    – mathnoob123
    Nov 26 '18 at 8:09














0












0








0





$begingroup$


I am using the Hopf Map $f: mathbb{S}^3 rightarrow mathbb{S}^2$ where $f(a,b,c,d) = (2(ab+cd),2(ad-cb),(a^2+c^2)-(b^2+d^2))$



My question is



1.) How can I prove surjectivity of the map? I am aware of the primary definition of surjectivity but I am unsure how to apply in this case.



I tried using the trivial method of finding an inverse but the method is very complicated.



2.) How can I show that a point that the preimage of $q in mathbb{S}^2$ is a circle in $mathbb{S}^3$?



I realize that the solution is dependent on finding the inverse function as hinted in the first part, but since the function itself was complicated to find, hence I had no progress in this part.










share|cite|improve this question











$endgroup$




I am using the Hopf Map $f: mathbb{S}^3 rightarrow mathbb{S}^2$ where $f(a,b,c,d) = (2(ab+cd),2(ad-cb),(a^2+c^2)-(b^2+d^2))$



My question is



1.) How can I prove surjectivity of the map? I am aware of the primary definition of surjectivity but I am unsure how to apply in this case.



I tried using the trivial method of finding an inverse but the method is very complicated.



2.) How can I show that a point that the preimage of $q in mathbb{S}^2$ is a circle in $mathbb{S}^3$?



I realize that the solution is dependent on finding the inverse function as hinted in the first part, but since the function itself was complicated to find, hence I had no progress in this part.







differential-geometry






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share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Nov 25 '18 at 22:58







mathnoob123

















asked Nov 25 '18 at 22:04









mathnoob123mathnoob123

693417




693417












  • $begingroup$
    It might be helpful to view the two-sphere and three-sphere in slighty different ways: we can view the two-sphere as $mathbb{C}P^1$, and the three-sphere as the elements in $mathbb{C}^2$ of magnitude 1. Then the Hopf map is given by $(z,w) mapsto [z:w]$.
    $endgroup$
    – Brian Shin
    Nov 26 '18 at 0:57












  • $begingroup$
    @BrianShin How can I demonstrate the equivalence of the two maps?
    $endgroup$
    – mathnoob123
    Nov 26 '18 at 8:09


















  • $begingroup$
    It might be helpful to view the two-sphere and three-sphere in slighty different ways: we can view the two-sphere as $mathbb{C}P^1$, and the three-sphere as the elements in $mathbb{C}^2$ of magnitude 1. Then the Hopf map is given by $(z,w) mapsto [z:w]$.
    $endgroup$
    – Brian Shin
    Nov 26 '18 at 0:57












  • $begingroup$
    @BrianShin How can I demonstrate the equivalence of the two maps?
    $endgroup$
    – mathnoob123
    Nov 26 '18 at 8:09
















$begingroup$
It might be helpful to view the two-sphere and three-sphere in slighty different ways: we can view the two-sphere as $mathbb{C}P^1$, and the three-sphere as the elements in $mathbb{C}^2$ of magnitude 1. Then the Hopf map is given by $(z,w) mapsto [z:w]$.
$endgroup$
– Brian Shin
Nov 26 '18 at 0:57






$begingroup$
It might be helpful to view the two-sphere and three-sphere in slighty different ways: we can view the two-sphere as $mathbb{C}P^1$, and the three-sphere as the elements in $mathbb{C}^2$ of magnitude 1. Then the Hopf map is given by $(z,w) mapsto [z:w]$.
$endgroup$
– Brian Shin
Nov 26 '18 at 0:57














$begingroup$
@BrianShin How can I demonstrate the equivalence of the two maps?
$endgroup$
– mathnoob123
Nov 26 '18 at 8:09




$begingroup$
@BrianShin How can I demonstrate the equivalence of the two maps?
$endgroup$
– mathnoob123
Nov 26 '18 at 8:09










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