ABSTRACT
6.1 Let A be any subset of R n such that O ⊂ A ⊂ Ō for an open set O in R n . A map f: A → R m is said to be smooth at a point p ∊ A if there is an open neighbourhood V 1 of p in R n and a smooth map f 1: V 1 → R m such that https://www.w3.org/1998/Math/MathML"> f 1 | A ∩ V 1 = f | A ∩ V 1 https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315366722/660a41ec-09ea-4535-a2aa-9fc9a667124f/content/in6_u001.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> .
