psibi / how-to-prove

My Solution to Velleman's book

Geek Repo:Geek Repo

Github PK Tool:Github PK Tool

2.1.2.c

Windings-Lab opened this issue · comments

commented

¬(Somebody failed the test) -> ∀y(If y got A grade, then y will tutor someone who got a D)

Can't we reduce the term and cut ∀y from this?
Because ∀y Є ¬(Somebody failed the test)
So
¬(∃x F(x)) -> (If x got an A grade, then x will tutor someone who got a D)
Because by the logic x is somebody who did not failed the test because he has got and A grade, isn't it?