Economic reality of groups of companies (yes) / Conditions for extending the scope of an agreement to arbitrate to companies the majority of whose shares are owned by a signatory of the contract containing the agreement to arbitrate: active role in the contractual negotiations or direct implication of the companies in the contract containing the agreement to arbitrate / Nonextension to companies in the group that do not meet either of these conditions / The notion of the principal shareholder as guarantor of the companies he controls is inimical to all concepts of representation / Right of the beneficiary of a stipulation to invoke the arbitration clause agreed to by the stipulating party (yes)