Section A2m.
Variable (l m v : nat) (Hv : Z.of_nat v = α (2+m) - α m).
Fact alpha_SSm_m_neq_0 : v <> 0%nat.
Notation Hv' := alpha_SSm_m_neq_0.
Let Z2Zp_morph := Z2Zp_morphishm Hv'.
Notation f := (Z2Zp Hv').
Notation "〚 x 〛" :=  (f x).
Notation "〘 x 〙" := (morph22 f x).
Notation "⊟" := (MI22 (Zp_opp Hv')).
Infix "⊠" := (MU22 (Zp_plus Hv') (Zp_mult Hv')) (at level 40, left associativity).
Let Am_iAm_mod :〘A m〙= ⊟〘iA m〙.
Fact A2m_mod : 〘A (2*m)〙= ⊟〘MZ_one〙.
Fact A2lm_mod : 〘A (2*l*m)〙= 〘MZ_scal (mscal Zmult 1 l (-1)) MZ_one〙.
Let expoZ_opp1 i : expoZ i (-1) = 1 \/ expoZ i (-1) = -1.
Variable (j : nat) (Hl : (l <> 0)%nat) (Hj : (j <= m)%nat).
Fact alpha_2lm_plus_j :〚α (S (2*l*m+j))〛=〚expoZ l (-1)*α (S j)〛.
Let Hj' : (j <= 2*l*m)%nat.
Fact alpha_2lm_minus_j :〚α (S (2*l*m-j))〛=〚expoZ (S l) (-1)*α (S j)〛.

Theorem alpha_nat_2lm_minus_j : nat2Zp Hv' (alpha_nat (2*l*m-j)) = nat2Zp Hv' (alpha_nat j)
\/ nat2Zp Hv' (alpha_nat (2*l*m-j)) = Zp_opp Hv' (nat2Zp Hv' (alpha_nat j)).