元素 | 可达集R (S) | 前因集A (S) | 交集C (S) |
S1 | 1, 2, 3, 4 | 1 | 1 |
S2 | 2, 4 | 1, 2 | 2 |
S3 | 3, 4 | 1, 3 | 3 |
S4 | 4 | 1, 2, 3, 4 | 4 |
S6 | 6 | 6 | 6 |