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Post by Admin on May 10, 2016 20:37:44 GMT
Gary
As part of my commentary on section XI, I completed the suggested exercise near the bottom of page 254 asking for a proof of $$f^{\dagger}(z)\equiv \overline{f\bigg(\frac{1}{\bar{z}}\bigg)}.$$ In the third and fourth lines from the bottom of page 254 Needham writes:
"By construction, this function sends symmetric pairs of points to conjugate images: $F^{\dagger}(z)=F(z)$". 'This function' refers to $F(z)$.
I immediately thought that it was strange to suddenly write $F^{\dagger}$ after writing $f^{\dagger}$ previously, and so I just wrote down the algebraic notation for the above quoted statement which in my opinion is:
$\overline{F(z)}=F(1/\bar{z})$
I then tried to prove it algebraically using the result of the last suggested exercise, shown at the top of this post, and I feel that I succeeded.
So in conclusion I would say that I feel reasonably sure that this is an error in the book, but I would like a second opinion before publishing it in the errata section. I thought you might have tried the suggested exercises etc on page 254, as your last post was about a later exercise. Any thoughts?
Vasco
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Gary
GaryVasco
Posts: 3,352
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Post by Gary on May 16, 2016 9:57:04 GMT
Vasco I see this message has been here for a week. For some reason, I’m not getting email notices of postings anymore. How are those notices triggered? I did do the exercise you mention, but I haven’t written it up yet. I’m afraid that I can’t make sense of $F^{\dagger}(z) \equiv F(z)$. I understand that F includes both $f$ and $f^{\dagger}$, but I just don’t have any grasp on how to use $F$ or $F^{\dagger}$ in equations. Your equation seems likely. I await the publication of your proof. But I have added to my previous document on Section XI with an attempt to summarize the section. I post it here and I will get rid of the old version soon. nh.ch5.schwarzian_reflection.pdf (210.42 KB) Gary
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Post by Admin on May 18, 2016 8:57:04 GMT
Gary
I think you only get an email when someone contributes to a topic you have contributed to. If I post a new thread then you don't get an email. I suggest looking in recent threads/posts. I have sent you a private message. Vasco
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Post by Admin on May 23, 2016 16:30:24 GMT
Gary Here is a first version of the proof. When I publish my commentary on section XI, which includes this proof, it may have been edited again. Let me know what you think about it. Thanks Vasco
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Post by Admin on May 23, 2016 18:48:11 GMT
Gary
I just noticed an error in my document. I have corrected it - I hope, and the link in the above post now points to the corrected version.
Vasco
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Gary
GaryVasco
Posts: 3,352
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Post by Gary on May 23, 2016 19:36:51 GMT
Gary Here is a first version of the proof. When I publish my commentary on section XI, which includes this proof, it may have been edited again. Let me know what you think about it. Thanks Vasco Vasco, It's a gem. I now understand how to use F. Gary
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