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show/hide this revision's text 2 corrected English technical term

A really elementary one :

A linear application map between two vector spaces of the same finite dimension is an isomorphism if and only if its kernel is zero.

As an application, I like the proof of the existence of Lagrange interpolation polynomials.
show/hide this revision's text 1 [made Community Wiki]

A really elementary one :

A linear application between two vector spaces of the same finite dimension is an isomorphism if and only if its kernel is zero.

As an application, I like the proof of the existence of Lagrange interpolation polynomials.