1楼答对了??11对应指的是AB集合中 A集合中所有元素在B集中都有象 且唯一. B集中所有元素在A集中也有象且唯一..并且 A集和 B集元素个数相等..楼上的你们的数学好烂就别乱指导别人.OK? One-to-One Function
A function for which every element of the range of the function corresponds to exactly one element of the domain. One-to-one is often written 1-1.
Note: y = f(x) is a function if it passes the vertical line test. It is a 1-1 function if it passes both the vertical line test and the horizontal line test. Another way of testing whether a function is 1-1 is given below.
1楼和3楼都搞混了one to one function和one to one correspondence。 one to one function是一对一函数,不是一一映射(one to one correspondence). one to one function是指对于集合A,B,对于A中的任两个元素,经过函数f都在B中有象且象两两不同,但并不是B中的所有元素都在A中有原象。所以|A|<=|B|.