It is possible that HammarskjBld got the idea of using profit as a link between consecutive periods from Keynes' Treatise (cp. ibid., pp.l25-126; pp.l41142). But HammarskjBld could as well have taken up an idea which was already developed by Wicksell in the formal example of a cumulative process in Interest and Prices, where the profit for the current period is realized at the end of the period and it can only influence the activities of the subsequent period (cp. Wicksell 1936, p.l42; cp. HammarskjBld 1933A, p.l2 n.l). There is just one explicit fact which gives a hint that the algebraic construction of a sequence of periods might have come from Robertson, who already constructed such a sequence in Banking Policy {cp. Robertson 1926, p.60f.); HammarskjBld has namely a methodological appendix to Chapter II of the dissertation with the following quotation from Robertson:

"The internal mechanism, so to speak, of a process of inflation are almost as hard to visualize as those of the atom, and seem to require the same kind of hypothesis of discontinuous motion" (HammarskjBld 1933A, p.53).