A whale is a mammal (m). If a whale is a mammal and a spider has six legs (s), then a frog is a reptile (r). But, a frog is not a reptile. Therefore, a spider does not have six legs.
m = a whale is a mammal s = a spider has six legs r = a frog is a reptile P1: m p2: (m ^ s) -> r p3: ~r therefore: ~s Steps Reason 1. m p1 - given 2. (m ^ s) -> r p2 - given 3. ~r p3 - given 4. ???
Apologies. I'm trying to help my daughter with this and I don't know the next step. We are trying to do the conjunction of any 2 of 1-3, but that doesn't result in any of the theorems that her cheat sheet shows.