I am in trouble , I searched a lot about how to solve this kind of questions but I did not get any answers.
I understand how can I know when the sentences is valid and Unsatisfiable in propositional logic, but in FOL I can't.
Can someone help me how can I solve this kind of questions? Because it comes always in the past exams in AI.
Let us have the following:
1- ¬(Speed(Processor(MyPC))=Speed(Processor(MyPC))) 2- ¬ ∃ x ( Speed(x) = Speed(MyPC) ) 3- Speed(MyPC)=MyPC 4- ∀ y ∃ x (Speed(x) ∧ Speed(y))= Speed(MyPC)
MyPC: a constant symbols that represents my PC. Speed(x): a function symbol that refers to speed of x
The answer for 1 is Syntactically wrong
2 is Unsatisfiable
3 is Neither valid nor unsatisfiable
4 is Syntactically wrong