chapter  2
Truth trees
Pages 16

We now have a slightly better vantage point from which to investigate the inferences with which we started in Chapter 1:

If Lev is in Moscow then Irina is in Kiev. Lev is in Moscow. ∴ Irina is in Kiev. Cain was hairy and Abel was his victim. ∴ Cain was hairy. It’s raining or it’s snowing. It’s not raining. ∴ It’s snowing.