Theorem
idd
≪
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index
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src
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≫
theorem idd (a b: wff): $ a -> b -> b $;
Step
Hyp
Ref
Expression
1
id
b -> b
2
1
a1i
a -> b -> b
Axiom use
axs_prop_calc
(
ax_1
,
ax_2
,
ax_mp
)