- #1
Euler2718
- 90
- 3
Homework Statement
Determine whether the following is valid:
[tex] p \rightarrow \neg q , r \rightarrow q , r, \vdash \neg p [/tex]
Homework Equations
Modus Ponens, disjunctive syllogism, double negation.
The Attempt at a Solution
I've boiled it down to
[tex] p \rightarrow \neg q , q, \vdash \neg p [/tex]
However I do not understand how the book says to use disjunctive syllogism and double negation here. I've expanded the implication into its fundamental forum but I still can't see it.