问题1:如何用图模型表达以下问题及其解? There is a related mathematical question here.Let U and W be two sets.Does there exist a one-to-one function f:U>W? lU<=|W What if the image of each element of U cannot be just any element of W? G: B M问题1:如何用图模型表达以下问题及其解? • There is a related mathematical question here. Let U and W be two sets. Does there exist a one-to-one function f : U → W ? • What if the image of each element of U cannot be just any element of W? |U|<=|W|