Assuming "z" is not found earlier in the proof, from ($x)($y)((Px

Question

Assuming "z" is not found earlier in the proof, from ($x)($y)((Px • Py) → Lxy) we may validly infer
A) ($x)((Px • Pb) → Lxb).
B) ($y)((Pa • Py) → Lay).
C) ($y)((Py • Py) → Lyy).
D) ($x)((Pa • Py) → Lay).

Quizplus · Accepted Answer

The original statement is a universal quantification over both x and y. By instantiating x with a specific constant 'a', we can infer ($y)((Pa • Py) → Lay), which is a valid inference.