Something my students are persistently confused about is when a quantifier has to be restricted and when it doesn't have to be. E.g., in a mixed domain you want to symbolize "Someone is blah". Do you have to restrict the \exists to people or not? When do you have to restrict? Can you symbolize "someone" without restricting to people? There should perhaps be some sort of discussion on this in the book.
E.g., I received the following by email:
A question about Sec 24.4. For the following example: Someone is a dog owner.
This symbolization is given: ∃y∃x(D(x) ∧O(y,x)) But since the domain includes both animals and human beings, shouldn't '∃y' be restricted? I.e., Something like ∃y∃x(D(x) ∧ Person(y) ∧ O(y,x)).
This is well taken, but the symbolization key doesn't even include a predicate for "person". Figure out what to do here.
Something my students are persistently confused about is when a quantifier has to be restricted and when it doesn't have to be. E.g., in a mixed domain you want to symbolize "Someone is blah". Do you have to restrict the \exists to people or not? When do you have to restrict? Can you symbolize "someone" without restricting to people? There should perhaps be some sort of discussion on this in the book.
E.g., I received the following by email:
This is well taken, but the symbolization key doesn't even include a predicate for "person". Figure out what to do here.