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












1












$begingroup$


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











$endgroup$








  • 1




    $begingroup$
    The proof starts with "Let $alpha < beta < 1$". What happens if $beta < alpha$?
    $endgroup$
    – AlexanderJ93
    Dec 6 '18 at 22:32












  • $begingroup$
    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?
    $endgroup$
    – KSM1743
    Dec 6 '18 at 22:39






  • 3




    $begingroup$
    The proof relies on $0<beta<1$, since that is a requirement for $cos(betasigma) > 0$ for all $sigmain[-pi/2,pi/2]$.
    $endgroup$
    – AlexanderJ93
    Dec 6 '18 at 22:43
















1












$begingroup$


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











$endgroup$








  • 1




    $begingroup$
    The proof starts with "Let $alpha < beta < 1$". What happens if $beta < alpha$?
    $endgroup$
    – AlexanderJ93
    Dec 6 '18 at 22:32












  • $begingroup$
    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?
    $endgroup$
    – KSM1743
    Dec 6 '18 at 22:39






  • 3




    $begingroup$
    The proof relies on $0<beta<1$, since that is a requirement for $cos(betasigma) > 0$ for all $sigmain[-pi/2,pi/2]$.
    $endgroup$
    – AlexanderJ93
    Dec 6 '18 at 22:43














1












1








1


2



$begingroup$


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











$endgroup$




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






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Dec 6 '18 at 22:34







KSM1743

















asked Dec 6 '18 at 22:25









KSM1743KSM1743

164




164








  • 1




    $begingroup$
    The proof starts with "Let $alpha < beta < 1$". What happens if $beta < alpha$?
    $endgroup$
    – AlexanderJ93
    Dec 6 '18 at 22:32












  • $begingroup$
    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?
    $endgroup$
    – KSM1743
    Dec 6 '18 at 22:39






  • 3




    $begingroup$
    The proof relies on $0<beta<1$, since that is a requirement for $cos(betasigma) > 0$ for all $sigmain[-pi/2,pi/2]$.
    $endgroup$
    – AlexanderJ93
    Dec 6 '18 at 22:43














  • 1




    $begingroup$
    The proof starts with "Let $alpha < beta < 1$". What happens if $beta < alpha$?
    $endgroup$
    – AlexanderJ93
    Dec 6 '18 at 22:32












  • $begingroup$
    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?
    $endgroup$
    – KSM1743
    Dec 6 '18 at 22:39






  • 3




    $begingroup$
    The proof relies on $0<beta<1$, since that is a requirement for $cos(betasigma) > 0$ for all $sigmain[-pi/2,pi/2]$.
    $endgroup$
    – AlexanderJ93
    Dec 6 '18 at 22:43








1




1




$begingroup$
The proof starts with "Let $alpha < beta < 1$". What happens if $beta < alpha$?
$endgroup$
– AlexanderJ93
Dec 6 '18 at 22:32






$begingroup$
The proof starts with "Let $alpha < beta < 1$". What happens if $beta < alpha$?
$endgroup$
– AlexanderJ93
Dec 6 '18 at 22:32














$begingroup$
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?
$endgroup$
– KSM1743
Dec 6 '18 at 22:39




$begingroup$
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?
$endgroup$
– KSM1743
Dec 6 '18 at 22:39




3




3




$begingroup$
The proof relies on $0<beta<1$, since that is a requirement for $cos(betasigma) > 0$ for all $sigmain[-pi/2,pi/2]$.
$endgroup$
– AlexanderJ93
Dec 6 '18 at 22:43




$begingroup$
The proof relies on $0<beta<1$, since that is a requirement for $cos(betasigma) > 0$ for all $sigmain[-pi/2,pi/2]$.
$endgroup$
– AlexanderJ93
Dec 6 '18 at 22:43










0






active

oldest

votes











Your Answer





StackExchange.ifUsing("editor", function () {
return StackExchange.using("mathjaxEditing", function () {
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
});
});
}, "mathjax-editing");

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "69"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});


}
});














draft saved

draft discarded


















StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3029139%2funderstanding-a-proof-why-is-it-necessary-that-alpha1%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown

























0






active

oldest

votes








0






active

oldest

votes









active

oldest

votes






active

oldest

votes
















draft saved

draft discarded




















































Thanks for contributing an answer to Mathematics Stack Exchange!


  • Please be sure to answer the question. Provide details and share your research!

But avoid



  • Asking for help, clarification, or responding to other answers.

  • Making statements based on opinion; back them up with references or personal experience.


Use MathJax to format equations. MathJax reference.


To learn more, see our tips on writing great answers.




draft saved


draft discarded














StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3029139%2funderstanding-a-proof-why-is-it-necessary-that-alpha1%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown





















































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown

































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown







Popular posts from this blog

How to change which sound is reproduced for terminal bell?

Can I use Tabulator js library in my java Spring + Thymeleaf project?

Title Spacing in Bjornstrup Chapter, Removing Chapter Number From Contents