Using Conjunctive Normal form to find when wff is true

[ChiralSuperfields]

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.