Proof by Resolution:(2) Obtain Clause Form

Coloured flowers are always scented.

(forall x) ( C(x) -> S(x) )

(forall x) (~C(x) v S(x) ) Rewrite -> using ~ and v.

~C(x) v S(x) Drop leading universal quantifier.

The other clauses are:

A(x) v D(x)

~A(x) v C(x)

(exists x) ~(~S(x) -> D(x) ) Move negation inward

(exists x) (~S(x) & ~D(x) ) DeMorgan’s law

~S(a) & ~D(a) Introduce Skolem constant

~S(a), ~D(a) Break into 2 clauses.

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