Let x0 of type ι be given.
Let x1 of type ι → ι → ι be given.
Let x2 of type ι be given.
Apply GroupE with
x0,
x1.
The subproof is completed by applying H0.
Apply H1 with
explicit_Group x2 x1.
Assume H4: x2 ⊆ x0.
Apply GroupE with
x2,
x1.
The subproof is completed by applying H3.
Claim L4: x2 ⊆ x0
Apply H1 with
x2 ⊆ x0.
Assume H5: x2 ⊆ x0.
The subproof is completed by applying H5.
Apply explicit_Group_identity_in with
x0,
x1.
The subproof is completed by applying L2.
Apply explicit_Group_identity_in with
x2,
x1.
The subproof is completed by applying L3.