I have the following facts that I would like to know if I correctly translated them to FOL.
All dogs howl at night.
∀x(Dog(x) -> Howl(x))
Anyone who has any cats will not have any mice.
∀x∀y(Cat(y) ∧ Have(x,y) -> ¬∃z (Mouse(z) ∧ Have (x,z)))
or (would like to know if this other way is possible as well)
∀x∀y(Cat(y) ∧ Have(x,y) -> ∀z (Mouse(z) -> ¬Have (x,z)))
Light sleepers do not have anything which howls at night.
∀x(LS(x) -> ∀y (Have(x,y) -> ¬ Howl(y)))
Peter has either a cat or a dog.
∃x((Dog(x) ∨ Cat(x)) ∧ Have(Peter,x))
If Peter is a light sleeper, then Peter does not have any mice.
LS(Peter) -> ∀y(Mouse(y) -> ¬Have(Peter, y))
Will these be correct translations?
Translations:
DOG(x): x is a dog
CAT(x): x is a cat
MOUSE(x): x is a mouse
HOWL(x): x howls at night
HAVE(x,y): x has y
LS(x): x is a light sleeper
$\endgroup$ 01 Answer
$\begingroup$Edit: The question was updated; this answer refers to the original posting.
You haven't specified the meanings of Howl, Have, etc. I have made the most charitable assumptions, but if I'm wrong you may need to make some changes (for instance, if "Howl" doesn't have "at night" baked in).
- This is probably fine.
- Your two options are logically equivalent, and they're logically equivalent to how I would translate it, but my personal preference would be for something like $\forall x\left((\exists y(\ldots))\to\ldots\right)$. Even though it's equivalent, the phrasing "has any cats" makes me think of an embedded $\exists y$.
- Your answers are odd because the sentence says "have" but you don't use the $\mathrm{Have}(x,y)$ construction.
- This is close, but your FOL form is false in a world with no cats at all, even though "Peter has either a cat or a dog" could still be true if he has a dog.
- This is probably fine.