Let x0 of type ι be given.
Apply nat_inv with
x0,
mul_nat 2 x0 ⊆ x0 ⟶ x0 = 0 leaving 3 subgoals.
The subproof is completed by applying H0.
Assume H1: x0 = 0.
The subproof is completed by applying H1.
Apply H1 with
mul_nat 2 x0 ⊆ x0 ⟶ x0 = 0.
Let x1 of type ι be given.
Apply H2 with
mul_nat 2 x0 ⊆ x0 ⟶ x0 = 0.
Apply H4 with
λ x2 x3 . mul_nat 2 x3 ⊆ x3 ⟶ x3 = 0.
Apply FalseE with
ordsucc x1 = 0.
Apply In_irref with
ordsucc x1.
Apply H5 with
ordsucc x1.
Apply ordsucc_in_double_nat_ordsucc with
x1.
The subproof is completed by applying H3.