Stability properties and periodic evolutions of bilinear systems in input-output form

Bilinear systems in input-output form are introduced and represented by mea ns of suitable rational functions in two indeterminates. Necessary and suff icient conditions for bounded-input/bounded-output (BIBO) stability are der ived and compared with analogous results on two-dimensional systems stabili ty. Several features of the output evolutions corresponding to finite suppo rt as web as to periodic input sequences are discussed and related to the p olar structure of the rational functions describing the input-output maps.