- #1
Florence
- 7
- 2
Homework Statement
I have to prove that ##(p \equiv q) \equiv ((p ∧ q) ∨ (¬p ∧ ¬q))##
With no premisses
In order to prove this, I first need to prove that:
##(p \equiv q) \to ((p ∧ q) ∨ (¬p ∧ ¬q))##
And:
##((p ∧ q) ∨ (¬p ∧ ¬q)) \to (p \equiv q)##
I was able to find the second implication, but I am still looking how I can prove the first one.
2. Homework Equations
I have the inference rules, contraposition, modus tollens ...
The Attempt at a Solution
I started with the hypothetical statement:
##(p \equiv q)##
But then I need to end the hypothetical statement with:
##((p ∧ q) ∨ (¬p ∧ ¬q))##
So I have tried to start a new hypothetical statement:
##¬((p ∧ q) ∨ (¬p ∧ ¬q))##
And to introduce a negation.
##¬((p ∧ q) ∨ (¬p ∧ ¬q)) \to (p \equiv q)## was easy to find, but I can't find a way to prove:
##¬((p ∧ q) ∨ (¬p ∧ ¬q)) \to ¬(p \equiv q)##
So that I could eliminate the negation afterwards.
I was looking to prove
##¬(p \equiv q)##
But I couldn't find a way to introduce the negation.
So I've tried to eliminate the disjuntion of:
##(p ∧ q) ∨ (¬p ∧ ¬q)##
By starting a new hypothetical statement, but this couldn't help me any futher.
Thank you in advance!