The purpose of this paper is to establish the equivalence of two axioms one of which appear in Nehring [1997] and the other in Nehring and Puppe [1999]. The one in Nehring and Puppe [1999] is due to Aizerman and Malishevski [1981]. We there by improve the existing characterisation of choice functions rationalized by extended partial orders. In appendix to this paper we provide a proof of a related statement appearing in Nehring [1997]. This paper makes extensive use of the rather elegant device known as finite mathematical induction.