Exercise logic.propositional.consequence
Description
Prove that formula is a logical consequence of a set of formulas
Derivation
![](http://ideas.cs.uu.nl/images/external.png)
p <-> r, q <-> s => (((p || q) /\ (r || s)) || ~(p || q)) /\ (((p || q) /\ (r || s)) || ~(r || s))
⇒ logic.propositional.oroverand, initial=TList [TCon logic1.equivalent [TVar "p",TVar "r"],TCon logic1.equivalent [TVar "q",TVar "s"]]p <-> r, q <-> s => (((p || q) /\ (r || s)) || ~(p || q)) /\ (p || q || ~(r || s)) /\ (r || s || ~(r || s))
⇒ logic.propositional.complorp <-> r, q <-> s => (((p || q) /\ (r || s)) || ~(p || q)) /\ (p || q || ~(r || s)) /\ T
⇒ logic.propositional.demorganorp <-> r, q <-> s => (((p || q) /\ (r || s)) || ~(p || q)) /\ (p || q || (~r /\ ~s)) /\ T
⇒ logic.propositional.oroverandp <-> r, q <-> s => (((p || q) /\ (r || s)) || ~(p || q)) /\ (p || q || ~r) /\ (p || q || ~s) /\ T
⇒ logic.propositional.truezeroandp <-> r, q <-> s => (((p || q) /\ (r || s)) || ~(p || q)) /\ (p || q || ~r) /\ (p || q || ~s)