I tried to give a detailed answer, but this stupid forum keeps on giving a database error
Although you said that it sounded like it might be a biconditional, you did not actually translate it
into FOL using a biconditional but you stated ExEy (Something ->
Something else)… chances are that if you have an Ex(P->Q) then it is probably wrong..
Here is my take on it, but don’t take my word for it though..
1)
Since Running (Q) is a necessary condition for Winning (P), we must write it in the form P->Q
(P is a sufficient condition for Q but Q is a necessary condition for P, ie, winning is a sufficient
reason for running, but running is a necessary condition to win the race)
2)
Using the term “Oneâ€, we have to assume that the speaker is generalizing, thus talking about
something that is true of everybody (every person in the domain), thus we will have to use a
universal quantifier (Ax)
3)
Since we want to talk about Early Bird as a race, we have to identify its free variable (earlybird)
in our FOL. We don’t want to introduce it for the first time inside the scope of any of our
quantifiers, so in this case it will be best if we state Race(earlybird) first and once we have done
that, continue writing the rest of our sentence, thus we start our sentence with
Race(earlybird) ^
4)
So, we can write Race(earlybird) ^ Ax(Wins(x,earlybird) ->.........)
5)
What gets me is the part “One runs 30km or more every weekâ€.
Does one write Ey(Runs(x,y) ^ ¬ LessThan(y,30))
or does one write Ay(Runs(x,y) -> ¬ LessThan(y,30)).
Runs(x,y) already means x Runs y km every week.
If we look at the Universal form, we may interpret it as saying “No kilometres that one runs
every week are less than 30â€.
If we look at the Existential form, we may interpret it as saying “Some kilometres that one runs
every week are not less than 30â€
From these interpretations, it would seem that we have to go the Universal route, thus
6)
Race(earlybird) ^ Ax(Wins(x,earlybird) -> Ay(Runs(x,y) -> ¬ LessThan(y,30)))
Is that the correct way of translating the particular sentence from English to FOL? I don’t know…
the study guide doesn’t give enough guidance so I cannot say yes with absolute certainty