Single business relationship. Arbitration clause in a contractual amendment that excludes from the arbitrator's consideration matters relating to the payment of the price, which remains subject to the main contract containing a state court forum selection clause. The question of whether the "premium" constitutes part of the price falls primarily within the arbitrator's jurisdiction. Prevalence of the Kompetenz-Kompetenz principle. A prior decision by another arbitral tribunal that tangentially addressed the issue is insufficient to displace the jurisdiction of the current arbitral tribunal, also by virtue of the Kompetenz-Kompetenz principle: