Comments, with reply, on "The controllability of planar bilinear systems" by D.E. Koditschek and K.S. Narendra

In the above-titled study (ibid., vol.AC-30, p.87-89, Jan. 1985) two classes of bilinear systems in the plane are examined, and it is claimed that necessary and sufficient conditions for complete controllability of both classes are derived. The commenter shows that the conditions for one of these classes are only sufficient. A counterexample is given. The authors briefly review their work and concede that the relevant theorem is incorrect.<
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