The joint arrangement Boréa, as defined in IFRS 11, is jointly controlled by Altis and Corva. It signs on its own behalf a three-year contract for a specified drilling vessel, with no substitution right for the supplier, and has exclusive use of it. The joint arrangement's committee decides the drilling sites, the schedule and the drilling depth; the supplier provides the crew, which follows these instructions, and may prohibit access to areas of armed conflict. Altis argues that, as neither company controls the vessel alone, there is no lease. Write a judgement memo.