his or her opinion the business before the Assembly renders his or her presence desirable. 2. The rules of procedure of the Assembly shall make provisions for a person so invited to take part in the proceedings of the Assembly relating to the matters in respect of which he or she was invited. ARTICLE 55 Meetings of the Assembly 1. The meetings of the Assembly shall be held at such times and places as the Assembly may appoint. 2. Subject to the provisions of paragraph 1 of this Article, the Assembly shall meet at least once in every year at Arusha in the United Republic of Tanzania and at a time to be determined by the Assembly. ARTICLE 56 Presiding in the Assembly There shall preside at any sitting of the Assembly: (a) the Speaker of the Assembly, or (b) in the absence of the Speaker of the Assembly, such elected member of the Assembly as the elected members may elect for the sitting. ARTICLE 57 Quorum and Vacancies in the Assembly 1. Subject to this Article, the rules of procedure of the Assembly shall make provision as to the number and composition of the elected members that shall constitute a quorum of the Assembly. 2. In reckoning the number of members who are present for the purposes of paragraph 1 of this Article, the person presiding shall not be taken into account. 42