Talk:Differentiation in Fréchet spaces

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Merge into Gateaux derivative[edit]

These articles describe the same concept. — Preceding unsigned comment added by 128.120.104.8 (talk) 20:04, 29 August 2014 (UTC)[reply]

Question regarding typing

U is an open set of X. X and Y are Frechet spaces, and in particular X and Y are closed to addition. F is a function U to Y. The formal definition of the derivative uses F(u+tv). However, I see no reason that u + tv is in U, and hence F may be undefined on u + tv. If the limit exists then there is a neighborhood where the addition makes sense and one is taking the limit over t and v such that u+tv is in U? I'm confused.