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Is there a way to categorise the valleys of a holomorphic function?


Show that the cross ratio is $f(z_1)$, where $f$ is the unique linear fractional transformationDerivatives of component mapsFind an analytic function that maps the disk $z$ onto the disk $<1$ so that $w(0)=1/2$ and $w(1)=0$Proof that there is a unique linear fractional transformation that maps three distinct points to three distinct points in the extended complex plane.Integrate complex function over $mathbbC^2$Injective holomorphic functionInequality derived from $f:mathbbDto mathbbD$ moving two points to another two pointsOnly three parameters to define a Möbius transformationBijections between subsets of $mathbbC times mathbbC$Bilinear transformation at infinity













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$begingroup$


For an entire function $f$, the input space $mathbbC$ is split into hills and valleys about the saddle points of $Re(f)$ by the maximum modulus theorem. Visually it is quite obvious whether or not two points (say $z_1,z_2$) are in the same valley. Is there a way to formalise this idea? In addition to this, is there some way to categorise $mathbbC$ around this quality? Ideally I would like to find some test that extends to functions $f:mathbbC^2 rightarrow mathbbC$ i.e holomorphic functions of 2 complex variables



I had thought one idea would be to take the steepest descent curves of starting from $z_1,z_2$. Then if $arg(z_1),arg(z_2) rightarrow theta$ we can say the two points must be in the same valley. We need the added stipulation that $Re(f(z_1)),Re(f(z_2))leq Re f(z_0)$ for the relevant saddle point $z_0$. I think this would work pointwise; can we use it or some different idea to categorise $mathbbC$ based on which valley the point belongs to?



I hope this would then extend to functions of 2 complex variables by writing $z,w=(z_1,z_2),(w_1,w_2) in mathbbC$ and checking that the arguments of $z_1,w_1$ and $z_2,w_2$ tend to the same limit. Does this sound sensible? Is there a better way to do it?










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    $begingroup$


    For an entire function $f$, the input space $mathbbC$ is split into hills and valleys about the saddle points of $Re(f)$ by the maximum modulus theorem. Visually it is quite obvious whether or not two points (say $z_1,z_2$) are in the same valley. Is there a way to formalise this idea? In addition to this, is there some way to categorise $mathbbC$ around this quality? Ideally I would like to find some test that extends to functions $f:mathbbC^2 rightarrow mathbbC$ i.e holomorphic functions of 2 complex variables



    I had thought one idea would be to take the steepest descent curves of starting from $z_1,z_2$. Then if $arg(z_1),arg(z_2) rightarrow theta$ we can say the two points must be in the same valley. We need the added stipulation that $Re(f(z_1)),Re(f(z_2))leq Re f(z_0)$ for the relevant saddle point $z_0$. I think this would work pointwise; can we use it or some different idea to categorise $mathbbC$ based on which valley the point belongs to?



    I hope this would then extend to functions of 2 complex variables by writing $z,w=(z_1,z_2),(w_1,w_2) in mathbbC$ and checking that the arguments of $z_1,w_1$ and $z_2,w_2$ tend to the same limit. Does this sound sensible? Is there a better way to do it?










    share|cite|improve this question











    $endgroup$














      0












      0








      0


      1



      $begingroup$


      For an entire function $f$, the input space $mathbbC$ is split into hills and valleys about the saddle points of $Re(f)$ by the maximum modulus theorem. Visually it is quite obvious whether or not two points (say $z_1,z_2$) are in the same valley. Is there a way to formalise this idea? In addition to this, is there some way to categorise $mathbbC$ around this quality? Ideally I would like to find some test that extends to functions $f:mathbbC^2 rightarrow mathbbC$ i.e holomorphic functions of 2 complex variables



      I had thought one idea would be to take the steepest descent curves of starting from $z_1,z_2$. Then if $arg(z_1),arg(z_2) rightarrow theta$ we can say the two points must be in the same valley. We need the added stipulation that $Re(f(z_1)),Re(f(z_2))leq Re f(z_0)$ for the relevant saddle point $z_0$. I think this would work pointwise; can we use it or some different idea to categorise $mathbbC$ based on which valley the point belongs to?



      I hope this would then extend to functions of 2 complex variables by writing $z,w=(z_1,z_2),(w_1,w_2) in mathbbC$ and checking that the arguments of $z_1,w_1$ and $z_2,w_2$ tend to the same limit. Does this sound sensible? Is there a better way to do it?










      share|cite|improve this question











      $endgroup$




      For an entire function $f$, the input space $mathbbC$ is split into hills and valleys about the saddle points of $Re(f)$ by the maximum modulus theorem. Visually it is quite obvious whether or not two points (say $z_1,z_2$) are in the same valley. Is there a way to formalise this idea? In addition to this, is there some way to categorise $mathbbC$ around this quality? Ideally I would like to find some test that extends to functions $f:mathbbC^2 rightarrow mathbbC$ i.e holomorphic functions of 2 complex variables



      I had thought one idea would be to take the steepest descent curves of starting from $z_1,z_2$. Then if $arg(z_1),arg(z_2) rightarrow theta$ we can say the two points must be in the same valley. We need the added stipulation that $Re(f(z_1)),Re(f(z_2))leq Re f(z_0)$ for the relevant saddle point $z_0$. I think this would work pointwise; can we use it or some different idea to categorise $mathbbC$ based on which valley the point belongs to?



      I hope this would then extend to functions of 2 complex variables by writing $z,w=(z_1,z_2),(w_1,w_2) in mathbbC$ and checking that the arguments of $z_1,w_1$ and $z_2,w_2$ tend to the same limit. Does this sound sensible? Is there a better way to do it?







      real-analysis complex-analysis analysis numerical-methods complex-integration






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