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lim sup {g(y) - g(a)} / (y - a) = L.

y-> a

It seems that this lemma exists: For all epsilon e > 0 and delta d > 0, there is an y such that 0 < l y - a l < d and g(y) > L - e.

Can someone give me some hint to proof this?

Thank you.

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# A lemma about upper derivatives (upper, non right)

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