The Game of Logic

by Lewis Carroll

13. All y' are x'. i.e. All invalids are unhappy.

14. Some y' exist. i.e. Some people are unhealthy.

15. Some y' are x, and some are x'. i.e. Some invalids are happy, and some are unhappy.

16. No y' exist. i.e. Nobody is unhealthy.

4. Smaller Diagram.

Propositions represented.

__________

------- -------
| 1 | | | | |
1. |---|---| 2. |---|---|
| 0 | | | 1 | |
------- -------

------- -------
| | | | | 1 |
3. |---|---| 4. |---|---|
| | 0 | | | |
------- -------

------- -------
| | 1 | | | |
5. |---|---| 6. |---|---|
| | | | 0 | |
------- -------