In the+procedure+arbitration+the omitted+observance+of the+principle+of the+contradictory+(sanctioned+by art.+816-bis,+co.+1,+cod.+Proc.+Civ.,+And+already+in precedence+ric Ondotto+in art.+816+of the Italian Civil Code+civ.)+not+is+a+formal vice+vice,+ma+activity.+nor+it follows+which,+to the+finical+of the+declaration+of+nullity,+it is+necessary+ascertain +the+concrete+impairment+of the+right+of+defense,+keeping+account+of the+mode+of the+comparison+between the+parts+(having+about+at+respective+claims)+of the+pos SIBLIBILE,+per+le+themselves,+of+exercise,+in+respect+of the+rule+audiatur+et+altera+pars,+on+a+floor+of+equality+the+faculties+procedural+them+attributed.