Theorem
absurdr
≪
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theorem absurdr (a b: wff): $ a -> ~a -> b $;
Step
Hyp
Ref
Expression
1
absurd
~a -> a -> b
2
1
com12
a -> ~a -> b
Axiom use
axs_prop_calc
(
ax_1
,
ax_2
,
ax_3
,
ax_mp
)