Question
Use rules of inference to show that if $\forall x(P(x) \vee Q(x))$ $\forall x(\neg Q(x) \vee S(x)), \quad \forall x(R(x) \rightarrow \neg S(x)),$ and $\exists x \neg P(x)$ are true, then $\exists x \neg R(x)$ is true.
Step 1
We have $\forall x(P(x) \vee Q(x))$ as our premise. By universal instantiation, we get $P(c) \vee Q(c)$. Show more…
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