Theorem
mpbi
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theorem mpbi (a b: wff): $ a <-> b $ > $ a $ > $ b $;
Step
Hyp
Ref
Expression
1
hyp h1
a <-> b
2
1
bi1i
a -> b
3
hyp h2
a
4
2
,
3
ax_mp
b
Axiom use
axs_prop_calc
(
ax_1
,
ax_2
,
ax_3
,
ax_mp
)