Understanding a proof. Why is it necessary that $alpha<1$?












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I'm reading the following proof from Lang's book of complex analysis. But I don't know why is it necessary that $alpha<1$?. I don't know where "$alpha<1$" is used . I don't understand either why $|g_{epsilon}(s)|to 0$ as $|s| to infty$. Can you help me, please?. I have been stuck for many hours.



Thank you for any help.



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  • 1




    The proof starts with "Let $alpha < beta < 1$". What happens if $beta < alpha$?
    – AlexanderJ93
    Dec 6 at 22:32












  • I think that $g_{epsilon}$ might fail to be bounded on the strip. But, if $alpha geq 1$, we could take $beta in (alpha, alpha+1)$ to show the theorem?
    – KSM1743
    Dec 6 at 22:39






  • 3




    The proof relies on $0<beta<1$, since that is a requirement for $cos(betasigma) > 0$ for all $sigmain[-pi/2,pi/2]$.
    – AlexanderJ93
    Dec 6 at 22:43
















1














I'm reading the following proof from Lang's book of complex analysis. But I don't know why is it necessary that $alpha<1$?. I don't know where "$alpha<1$" is used . I don't understand either why $|g_{epsilon}(s)|to 0$ as $|s| to infty$. Can you help me, please?. I have been stuck for many hours.



Thank you for any help.



enter image description here










share|cite|improve this question




















  • 1




    The proof starts with "Let $alpha < beta < 1$". What happens if $beta < alpha$?
    – AlexanderJ93
    Dec 6 at 22:32












  • I think that $g_{epsilon}$ might fail to be bounded on the strip. But, if $alpha geq 1$, we could take $beta in (alpha, alpha+1)$ to show the theorem?
    – KSM1743
    Dec 6 at 22:39






  • 3




    The proof relies on $0<beta<1$, since that is a requirement for $cos(betasigma) > 0$ for all $sigmain[-pi/2,pi/2]$.
    – AlexanderJ93
    Dec 6 at 22:43














1












1








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2





I'm reading the following proof from Lang's book of complex analysis. But I don't know why is it necessary that $alpha<1$?. I don't know where "$alpha<1$" is used . I don't understand either why $|g_{epsilon}(s)|to 0$ as $|s| to infty$. Can you help me, please?. I have been stuck for many hours.



Thank you for any help.



enter image description here










share|cite|improve this question















I'm reading the following proof from Lang's book of complex analysis. But I don't know why is it necessary that $alpha<1$?. I don't know where "$alpha<1$" is used . I don't understand either why $|g_{epsilon}(s)|to 0$ as $|s| to infty$. Can you help me, please?. I have been stuck for many hours.



Thank you for any help.



enter image description here







complex-analysis complex-numbers






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share|cite|improve this question













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edited Dec 6 at 22:34

























asked Dec 6 at 22:25









KSM1743

164




164








  • 1




    The proof starts with "Let $alpha < beta < 1$". What happens if $beta < alpha$?
    – AlexanderJ93
    Dec 6 at 22:32












  • I think that $g_{epsilon}$ might fail to be bounded on the strip. But, if $alpha geq 1$, we could take $beta in (alpha, alpha+1)$ to show the theorem?
    – KSM1743
    Dec 6 at 22:39






  • 3




    The proof relies on $0<beta<1$, since that is a requirement for $cos(betasigma) > 0$ for all $sigmain[-pi/2,pi/2]$.
    – AlexanderJ93
    Dec 6 at 22:43














  • 1




    The proof starts with "Let $alpha < beta < 1$". What happens if $beta < alpha$?
    – AlexanderJ93
    Dec 6 at 22:32












  • I think that $g_{epsilon}$ might fail to be bounded on the strip. But, if $alpha geq 1$, we could take $beta in (alpha, alpha+1)$ to show the theorem?
    – KSM1743
    Dec 6 at 22:39






  • 3




    The proof relies on $0<beta<1$, since that is a requirement for $cos(betasigma) > 0$ for all $sigmain[-pi/2,pi/2]$.
    – AlexanderJ93
    Dec 6 at 22:43








1




1




The proof starts with "Let $alpha < beta < 1$". What happens if $beta < alpha$?
– AlexanderJ93
Dec 6 at 22:32






The proof starts with "Let $alpha < beta < 1$". What happens if $beta < alpha$?
– AlexanderJ93
Dec 6 at 22:32














I think that $g_{epsilon}$ might fail to be bounded on the strip. But, if $alpha geq 1$, we could take $beta in (alpha, alpha+1)$ to show the theorem?
– KSM1743
Dec 6 at 22:39




I think that $g_{epsilon}$ might fail to be bounded on the strip. But, if $alpha geq 1$, we could take $beta in (alpha, alpha+1)$ to show the theorem?
– KSM1743
Dec 6 at 22:39




3




3




The proof relies on $0<beta<1$, since that is a requirement for $cos(betasigma) > 0$ for all $sigmain[-pi/2,pi/2]$.
– AlexanderJ93
Dec 6 at 22:43




The proof relies on $0<beta<1$, since that is a requirement for $cos(betasigma) > 0$ for all $sigmain[-pi/2,pi/2]$.
– AlexanderJ93
Dec 6 at 22:43















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