Assume H1.
Let y be given.
Let x' be given.
Apply SNoR_E x Hx x' Hx' to the current goal.
Assume Hx'1 Hx'2 Hx'3.
Apply SNoS_I2 x' x Hx'1 Hx Hx'2 to the current goal.
We prove the intermediate
claim Lx'pos:
0 < x'.
An
exact proof term for the current goal is
SNoLt_tra 0 x x' SNo_0 Hx Hx'1 Hxpos Hx'3.
Apply IH1 y Hy to the current goal.
Apply Hg x' Lx' Lx'pos to the current goal.
We prove the intermediate
claim Ly':
SNo y'.
An exact proof term for the current goal is L1 x' Lx' Lx'pos y y' Hy1 H2.
Apply andI to the current goal.
An exact proof term for the current goal is Ly'.
Apply SNo_recip_lem3 x x' (g x') y y' Hx Hxpos Hx' Hgx'1 Hgx'2 Hy1 Hxy1 Ly' to the current goal.
An exact proof term for the current goal is L2 x' Lx' Lx'pos y y' Hy1 H2.