Mojtahedzadeh, Mohammad T. with George P. Richardson, "Confusion in the Polarity of Major Loops", 1995
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There is an a priori in the system dynamics paradigm which implies that the behavior of a system is tightly related to its structure. A structure specifies the relationship between the elements of the system in term of stocks and flows and feedback loops. The attempt is to explain the behavior of a system based upon the accumulation in a system and its positive and negative feedback loops. This note introduces the concept of implicit loops or pathways, as components of a major loop, to explain how changes in the behavior of a variable of the system occur over time. The note demonstrates that they presence of a negative loop (explicit or implicit) around a positive loop (explicit or implicit) is necessary in order for a system to oscillate. In particular, in explains how a pure positive major loop can oscillate.