Let z be given.
Assume Hz.
Let p be given.
Assume Hp.
Apply ReplE_impred (complex ⨯ complex) (λu ⇒ pa (u 0) (u 1)) z Hz to the current goal.
Let u be given.
Assume Hzu: z = pa (u 0) (u 1).
An exact proof term for the current goal is Hp (u 0) (ap0_Sigma complex (λ_ ⇒ complex) u Hu) (u 1) (ap1_Sigma complex (λ_ ⇒ complex) u Hu) Hzu.
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