Although classical methods of structural analysis are important in understanding the behaviour of structures, they are not suitable for algorithmic programming. The force method of analysis, that in many cases leads to smaller systems of equations, proceeds from equilibrium and enforces compatibility, whereas the displacement method, that today dominates the scene, proceeds from the compatibility and enforces the equilibrium at the joints of an indeterminate structure. In this paper, a recursive force method is developed which is based on the concept of the (n-l) structure. The conditions of compatibility are enforced on the (n-l) redundant structure, until the (n-l) structure becomes a statically determinate structure. The required flexibility coefficients are calculated using the unit load theorem. The number of the required flexibility coefficients is the same as compared with the redundant force method. The recursive force method is programmed in Prolog and the basic predicates are presented. The method is illustrated with certain examples.

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