Let x0 of type ι be given.
Let x1 of type ι be given.
Let x2 of type ι be given.
Assume H3: x0 ⊆ x1.
Apply ordinal_In_Or_Subq with
x0,
x1,
add_nat x0 x2 ⊆ add_nat x1 x2 leaving 4 subgoals.
Apply nat_p_ordinal with
x0.
The subproof is completed by applying H0.
Apply nat_p_ordinal with
x1.
The subproof is completed by applying H1.
Assume H4: x0 ∈ x1.
Apply unknownprop_5699b3df204a64fe208917e4d013131a9b09ccf51d6c02bdbd470402e8fe7c26 with
x2,
x0,
x1 leaving 4 subgoals.
The subproof is completed by applying H2.
The subproof is completed by applying H0.
The subproof is completed by applying H1.
The subproof is completed by applying H4.
Apply nat_p_ordinal with
add_nat x1 x2,
add_nat x0 x2 ⊆ add_nat x1 x2 leaving 2 subgoals.
Apply add_nat_p with
x1,
x2 leaving 2 subgoals.
The subproof is completed by applying H1.
The subproof is completed by applying H2.
Apply H6 with
add_nat x0 x2.
The subproof is completed by applying L5.
Assume H4: x1 ⊆ x0.
Claim L5: x0 = x1
Apply set_ext with
x0,
x1 leaving 2 subgoals.
The subproof is completed by applying H3.
The subproof is completed by applying H4.
Apply L5 with
λ x3 x4 . add_nat x4 x2 ⊆ add_nat x1 x2.
The subproof is completed by applying Subq_ref with
add_nat x1 x2.