The Ext functor is defined by taking a resolution of modules with this property and producing a cochain complex of hom classes. A group representation is faithful if the map from the group to the endomorphism group of a vector space has this property. Homomorphisms that have this property are called monic and have a trivial kernel. Linear transformations with this property must have an image with the same dimension as the domain and are described as “full rank.” Embeddings of sets trivially have this property. A surjective map that has this property is bijective. This property is possessed by functions that pass the “horizontal line test.” For 10 points, name this property of functions that map different inputs to different outputs. ■END■