Yes, a function is an injection [1]. Abstractly. Listing all possible inputs with their outputs, and then doing a lookup....that's only sometimes useful. [1]

Yes, a function is an injection [1]. Abstractly. Listing all possible inputs with their outputs, and then doing a lookup....that's only sometimes useful. [1] https://en.wikipedia.org/wiki/Injective_function https://en.wikipedia.org/wiki/Injective_function