Subsection 5.2.4 Universal Instantiation Proof Problem: Fathers and Sons
FathersAndSons
Assume the universe of male people. We assume that if anyone is the father of some person then that father cannot be the son of his own son. Thus no one is his own father.
Assign the following names to basic statements:
F(x, y): True if x is the father of y.
Prove: ∀x (∀y (F(x, y) → ¬F(y, x))) If anyone is the father of some person then
that father cannot be the son of his own son.
∴ ∀x ( ¬F(x, x)) No one is his own father.
You should do this proof yourself.
You can also watch our video, which will outline our strategy for doing this.
