|Mar28-12, 09:40 AM||#1|
Help with indirect logic proof please!
Using the five axioms below prove: p→q
A4: x→ q or z
A5: r→x or y
Do I have to take the contrapositive of some of the axioms to begin this proof?
|Mar28-12, 10:01 AM||#2|
Yes, that would be the simplest thing to do. The very first "axiom" gives you p-> ~y but there is no "~y-> " so you cannot continue directly. However, you do have "A5: r->x or y which has contrapositive ~(x or y)= (~x) and (~y)->~r and then both "A2: ~r-> q" and "A4: x-> q or z".
|Mar28-12, 01:03 PM||#3|
Am I on the right track with this?
1. p Given
2. ~z or ~y All cases
3. ~z Case 1
4. ~x A4
5. ~r A5
6. q A2
|Similar Threads for: Help with indirect logic proof please!|
|Help with indirect logic proof please!||Set Theory, Logic, Probability, Statistics||1|
|Indirect Proof||Precalculus Mathematics Homework||2|
|Indirect Proof||Calculus & Beyond Homework||5|
|Indirect Proof (Logic question)||Set Theory, Logic, Probability, Statistics||6|
|Help with an indirect proof (RAA)||General Discussion||1|