category theory

# Contents

## Definition

A functor $F: C \to D$ from the category $C$ to the category $D$ is faithful if for each pair of objects $x, y \in C$, the function

$F : C(x,y) \to D(F(x), F(y))$

is injective.

More abstractly, we may say a functor is faithful if it is $2$-surjective – or loosely speaking, ‘surjective on equations between given morphisms’.

See also faithful morphism for a generalization to an arbitrary 2-category.

Revised on December 21, 2011 19:22:45 by Urs Schreiber (82.113.98.205)