| Clue | Source | Date |
|---|---|---|
| In which 'P or Q, but not both' is represented as (P∨Q)∧¬(P∧Q) | New York Times | 02 Jul 2023 |
| In which 'P or Q, but not both' is represented as (P?Q)?¬(P?Q) | New York Times | 02 Jul 2023 |
| Visual aid to reasoning | The Times Concise | 05 Jun 2019 |
| Formal system used in statement analysis |