For each of the following sentences in English, decide if the accompanying first-order logic sentence is a good translation. If not, explain why no and correct it. (Some sentences may have more than one error.)
a. No two people have the same social security number
¬∃x, y,n Person(x) ∧ Person(y) ⇒ [HasSS#(x, n) ∧ HasSS#(y, n)].
b. John's social security number is same as the Mary's
∃n HasSS#(John, n) ∧ HasSS#(Mary, n).
c. Everyone's social security number has nine digits.
∀x, n Person(x) ⇒ [HasSS#(x, n) ∧ Digits(n,9)].
d. Rewrite each of the above (uncorrected) sentences using a function symbol SS# instead of the predicate HasSS#.