Question
Prove that the following arguments are standard by constructing metaphorical proof
$(A\ v\ B) \rightarrow (D\ v\ C)$
$(E\ v\ F)\ v\ (A\ v\ B)$
$\sim (A\ v\ B)\ \&\ H$
$F \rightarrow (A\ v\ B)$
$\therefore [E\ \&\ \sim (A\ v\ B)]\ v\ S$

Answer

$(1)\ (A\ v\ B) \rightarrow (D\ v\ C)$ $P$
$(2)\ (E\ v\ F)\ v\ (A\ v\ B)$ $P$
$(3)\ \sim (A\ v\ B)\ \&\ H$ $P$
$(4)\ F \rightarrow (A\ v\ B)$ $P/ \therefore [E\ \&\ \sim (A\ v\ B)]\ v\ S$
$(5)\ \sim (A\ v\ B)$ $3,$ Simp.
$(6)\ E\ v\ F$ $2, 5, DS$
$(7) \ \sim F$ $4, 5, MT$
$(8)\ E$ $6, 7 DS$
$(9)\ R\ \&\ \sim (A\ v\ B)$ $8, 5,$ Conj.
$(10)\ (R\ \&\ \sim (A\ v\ B)\ v\ S$ $9,$ Add.

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