From various comments made, especially by Fred, I think the intended problem is something like this:
Given two finite cylinders C_r, C_R of radii r < R and equal heights in R^3, how many constraints of the form ||x_j - y_j|| = c_j, for x_j in C_r and y_j in C_R in order to require C_r to be fixed in a uniqconcentric I wrote: << In the biography of H.S.M. Coxeter "King of Infinite Space", one section describes his interaction with Buckminster Fuller. It states that Fuller erroneously claimed that a bicycle wheel needs 12 spokes "to hold it rigid", whereas the correct number is 7. This seems to be stated as a fact of geometry, rather than one of structural engineering. Anybody have any insight into this claim?
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