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Post by Admin on Jun 7, 2017 8:58:52 GMT
Gary
This may just be a personal thing, but in doing the exercises 16-22 I have found the notational inconsistencies between quite a lot of the text of chapter 7, especially sections IV through VIII, and these exercises to be quite confusing.
For the most part, in the text, $p$ is used to represent a value of $f$ in the $f$-plane of the mapping $z\mapsto f$, and the word $p$-point is used to denote a preimage of $p$ in the $z$-plane. This is particularly prominent in subsection 1 of section IV on pages 346-347.
However, in the exercises 16-22, $p$ is used as a point in the $z$-plane and particularly in exercise 19. This has the potential to cause confusion particularly as the exercise talks about the critical point $p$ of an analytic function and the modular surface above $p$ etc. This exercise requires one to use the results and ideas in the subsection mentioned above, where $a$ is used as a root or critical point and $p$ is used as the value of $f$ at the critical point.
I find it quite difficult to envisage the $z$-plane, the mapping $z\mapsto f$ to the $f$-plane, the modular surface, points on the modular surface, etc. and this inconsistency in the notation just makes it worse.
Vasco
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Gary
GaryVasco
Posts: 3,352
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Post by Gary on Jun 7, 2017 13:54:29 GMT
Gary This may just be a personal thing, but in doing the exercises 16-22 I have found the notational inconsistencies between quite a lot of the text of chapter 7, especially sections IV through VIII, and these exercises to be quite confusing. For the most part, in the text, $p$ is used to represent a value of $f$ in the $f$-plane of the mapping $z\mapsto f$, and the word $p$-point is used to denote a preimage of $p$ in the $z$-plane. This is particularly prominent in subsection 1 of section IV on pages 346-347. However, in the exercises 16-22, $p$ is used as a point in the $z$-plane and particularly in exercise 19. This has the potential to cause confusion particularly as the exercise talks about the critical point $p$ of an analytic function and the modular surface above $p$ etc. This exercise requires one to use the results and ideas in the subsection mentioned above, where $a$ is used as a root or critical point and $p$ is used as the value of $f$ at the critical point. I find it quite difficult to envisage the $z$-plane, the mapping $z\mapsto f$ to the $f$-plane, the modular surface, points on the modular surface, etc. and this inconsistency in the notation just makes it worse. Vasco Vasco, I don't think it is just a personal thing. I did not identify the difficulty as you have, but I do remember experiencing mental lurches, particularly at exercise 19. I suspect it happens because the author has the concepts he wants to present clearly in mind and the notation becomes secondary. Then, one does not always remember to review for consistency of usage. I think it became my practice to determine at the beginning of an exercise whether p was in the preimage or the image. It should help anyone doing the exercises to know that p unexpectedly takes on different roles. But I think it is only in 16-19 that p is in the z-plane. In 21 and 22, it is back to the f-plane. Which just proves your point. Gary
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