In hypothesis of arbitration multipart in miss the agreement on the appointment of the referees, the procedure started a part part si trains in as many procedures how many are the parts, salvo that they exist a 'hypotheses of litisconsorzio necessary, in presence of the which the arbitration is unprocessable. and vi is litisconsorzio necessary only the the substantial situation multi -subjective deduced in judgment Deb Ba being necessarily decisive in unitary way towards comparisons all i subjects what nor are they partners, like in the case of action that curtain at constitution or at change a ratio pluriso ratio GGETIVE SINGLE; not appeals instead a hypothesis of litisconsorzio necessary when the cause has ad object an obligation solidarity, since the creditor has title of demand from each debtor the whole.