Let m and n be given.
Assume Hm Hn Hmn.
Apply nat_ind to the current goal.
We will prove m * 0 n * 0.
rewrite the current goal using mul_nat_0R (from left to right).
rewrite the current goal using mul_nat_0R (from left to right).
Apply Subq_ref to the current goal.
Let k be given.
Assume Hk: nat_p k.
Assume IHk: m * k n * k.
We will prove m * ordsucc k n * ordsucc k.
rewrite the current goal using mul_nat_SR m k Hk (from left to right).
rewrite the current goal using mul_nat_SR n k Hk (from left to right).
We will prove m + m * k n + n * k.
Apply Subq_tra (m + m * k) (m + n * k) (n + n * k) to the current goal.
We will prove m + m * k m + n * k.
Apply add_nat_Subq_L m Hm (m * k) (mul_nat_p m Hm k Hk) (n * k) (mul_nat_p n Hn k Hk) to the current goal.
We will prove m * k n * k.
An exact proof term for the current goal is IHk.
We will prove m + n * k n + n * k.
An exact proof term for the current goal is add_nat_Subq_R m Hm n Hn Hmn (n * k) (mul_nat_p n Hn k Hk).