Symbolic Logic

by Lewis Carroll

Univ. is “things”; m = fat; x = pigs; y = fed on barley-water.

x₁m′₀ † ym₀ ¶ x₁y₀ [Fig. I (α).

i.e. Pigs are not fed on barley-water.

19. All rabbits, that are not greedy, are black;
No old rabbits are free from greediness.

Univ. is “rabbits”; m = greedy; x = black; y = old.

m′₁x′₀ † ym′₀ ¶ xy′₁ [Fig. III.

i.e. Some black rabbits are not old.

20. Some pictures are not first attempts;
No first attempts are really good.

Univ. is “things”; m = first attempts; x = pictures; y = really good.

xm′₁ † my₀ ¶ nothing.