There are two types of mathematical economists, one who applies existing mathematics to economic problems (the best example is Court) and the other who anticipates new mathematical problems within economics. Taking Marx as the second type of economist (Section 1), I discuss two of his problems: the fundamental Marxian theorem (Section 2) and the transformation problem (Section 3). In Section 2 I propose a generalisation of the theorem to the effect that the theorem does not need the labour theory of value and hence is independent of any criticisms of that theory. In Section 3 it is seen that the transformation problem is formally identical with the Markov chain process transforming the initial position to the ergodic position.