Symbolic Logic

by Lewis Carroll

13. xm₀ † y′₁m′₀ ¶ y′₁x₀ [Fig. I (α).] Concl. right.

14. m′₁x₀ † m′₁y′₀ ¶ x′y₁ [Fig. III.] Concl. right.

15. mx′₁ † y₁m₀ ¶ x′y′₁ [Fig. II.] Concl. right.

16. x′m₀ † y′₁m₀ Fallacy of Like Eliminands not asserted to exist.

17. m′x₀ † m′₁y₀ ¶ x′y′₁ [Fig. III.] Concl. right.

18. x′m₀ † my₁ ¶ xy₁ [Fig. II.] Concl. right.

19. mx′₁ † m₁y′₀ ¶ x′y₁ [Fig. II.] Concl. right.

20. x′m′₀ † m′y′₁ ¶ xy′₁ [Fig. II.] Concl. right.

21. mx₀ † m₁y₀ ¶ x′y′₁ [Fig. III.] Concl. right.

22. x′₁m′₀ † ym′₁ ¶ xy₁ [Fig. II.] Concl. wrong: the right one is “Some x are y.”