Apply Hqr1 to the current goal.
Let δ be given.
Assume Hqr2.
Apply Hqr2 to the current goal.
Assume Hd1 Hd2.
Assume Hqr3.
Apply Hqr3 to the current goal.
Assume Hqr3.
Apply Hqr3 to the current goal.
Assume Hqr5: r δ.
We will
prove PNoLt α p β r.
We use δ to witness the existential quantifier.
Apply andI to the current goal.
An exact proof term for the current goal is Hd.
Apply and3I to the current goal.
An exact proof term for the current goal is Hpq.
An exact proof term for the current goal is Hqr3.
Assume H1: p δ.
Apply Hqr4 to the current goal.
We will prove q δ.
An
exact proof term for the current goal is
iffEL (p δ) (q δ) (Hpq δ Hd1) H1.
We will prove r δ.
An exact proof term for the current goal is Hqr5.