Using Conjunctive Normal form to find when wff is true

[member 731016]

Homework Statement

I am trying to understand how to tell which values for a proposition need to be taken on to make a CNF true.

Relevant Equations

CNF notation

For this,

Does someone please know how setting $P_1$ and $P_2$ true makes the CNF true? If I see $P_2$ true, then it $(true + false)$ since it is negated. Therefore, should they be setting $P_1$ true and $P_2$ false?

Many thanks!

 

[andrewkirk]

Homework Statement: I am trying to understand how to tell which values for a proposition need to be taken on to make a CNF true.
Relevant Equations: CNF notation

For this,
View attachment 329444
Does someone please know how setting $P_1$ and $P_2$ true makes the CNF true? If I see $P_2$ true, then it $(true + false)$ since it is negated. Therefore, should they be setting $P_1$ true and $P_2$ false?

Many thanks!

As it says, "+" specifies OR ($\vee$),
so (true + false) = (true OR false) = true.
So setting P1 and P2 true gives:
(T + F) (T + ? + ?) (T + ?)
which is (T) (T) (T)
since (True OR anything) is True
so the overall result is T.