Resolution Example[Chang and Lee, Symbolic Logic and
Mechanical Theorem Proving, Academic Press, 1973.]
- The customs officials searched everyone who entered the country
who was not a V.I.P.
- Some of the drug pushers entered the country, and they were only
searched by drug pushers.
- No drug pusher was a V.I.P.
- Conclusion: Some of the officials were drug pushers.
- &forall x ( E(x) &and ¬ V(x) &rarr
&exist y ( S(x,y) &and C(y)) )
- &exist x ( P(x) &and E(x) &and
&forall y ( S(x,y) &rarr P(y) ) )
- &forall x ( P(x) &rarr ¬ V(x) )
- &exist x ( P(x) &and C(x) )