There is a cross relationship between concept A and concept B if and only if (1) the existing object belongs to both A and B; (2) The existing object belongs to A but not to B; (3) The existing object belongs to B but not A.
According to the subject matter, paintings mainly include figure painting, flower and bird painting, landscape painting, etc; According to techniques, there are mainly meticulous painting and freehand painting is the cross relationship between the two concepts of adding points according to the above definition.