From CS2800 wiki

To say there is a unique value x satisfying some property [math]P [/math] is the same as saying that if there were two values [math]x_1 [/math] and [math]x_2 [/math] both satisfying [math]P [/math], then [math]x_1 = x_2 [/math].


  • In the definition of an injective function, we require that there any [math]x [/math] with [math]f(x) = y [/math] must be unique for all [math]y [/math].