Controversy concerning a contract for the purchase and sale of shares at a variable price with an arbitration clause. Filing of an enforcement action by the judgment creditor and institution of arbitration proceedings by the judgment debtor in which the arbitral tribunal recognized its jurisdiction. Primacy of the kompetenz-kompetenz principle. Inadmissibility of the debtor's petition to challenge execution proceedings and of the continuation of the enforcement action in view of the ongoing arbitration proceedings. Grant of emergency relief conferring stay of execution on the special appeal to suspend the continuation of the enforcement action: