Minority shareholder's claim for damages against the appellant corporation and its former controlling shareholder for the devaluation of the corporation's shares. Objection based on an arbitration agreement not raised in the joint answer filed by the defendants. Subsequent acknowledgment, by the claimant, of an arbitration clause in relation to the corporation. Request to continue the claim before the judiciary solely with respect to the former controlling shareholder. Possibility. Absence of compulsory joinder between the corporation and the former controlling shareholder in the case. Dismissal of the proceedings against the corporation: