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Mismached functions in page 133 theorem 4.2.3 #1087

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wgbusch opened this issue Aug 5, 2021 · 1 comment
Open

Mismached functions in page 133 theorem 4.2.3 #1087

wgbusch opened this issue Aug 5, 2021 · 1 comment

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@wgbusch
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wgbusch commented Aug 5, 2021

I think there is a typo in page 133, theorem 4.2.3.

"Proof. Suppose that (g, eta, epsilon) is a quasi-inverse for f ."

In the definition of qinv, the first coordinate corresponds to an homotopy between fg and Id. In the theorem it is called eta. But in the definition of ishae (page 132), eta is taken to be an homotopy between gf and Id. I think that this mismatch would be fixed simply by changing the first sentence of the proof to be "suppose that (g, epsilon, eta) is a quasi-inverse...", to match the definitions of eta and epsilon

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@mikeshulman
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Hmm, you seem to be right. Would you like to submit a pull request?

I think there is a similar mismatch between Definition 4.3.1 and equation (2.4.10).

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