二维分布函数F(x,y)的三条基本性质 1.F(x,y)是变量x,y的非减函数 即∨y∈R取定,当x1<x2时, F(x1,y)≤F(x2,y) 同样,Vx∈R取定,当y1≤y2时, F(x,y1)≤F(x,y2) 2.Vx,y∈R1有0≤F(x,y)≤1二维分布函数F(x,y)的三条基本性质 1. F(x,y)是变量x,y的非减函数. 即 yR 1取定,当x1<x2时, F(x1,y)≤F(x2,y). 同样, xR 1取定,当y1≤y2时, F(x,y1)≤F(x,y2). 2.  x,y R 1 有 0≤F(x,y)≤1