For proving , by , it suffices to prove

.

We prove the individual conjunctive parts of :

Proof of :

Formula is simplified to

.

For proving , by , it suffices to prove

.

From by specialization we obtain

.

From by specialization we obtain

.

We prove first

.

We prove the individual conjunctive parts of :

From and we obtain by modus ponens

Proof of :

Formula is true because it is identical to .