| Giver | Post | Date |
| PGN | If x is a member of the set {a, b, c, d}, where a, b, c, and d are the | 07-Sep-2016 |
| ishan92 | If x is a member of the set {a, b, c, d}, where a, b, c, and d are the | 22-Jun-2016 |
| grr8pe | If x is a member of the set {a, b, c, d}, where a, b, c, and d are the | 11-Jun-2015 |