  A Lebesgue-type decomposition of a (non necessarily non-negative)
sesquilinear form with respect to a non-negative one is studied. This
decomposition consists of a sum of three parts: two are dominated by an
absolutely continuous form and a singular non-negative one, respectively, and
the latter is majorized by the product of an absolutely continuous and a
singular non-negative forms. The Lebesgue decomposition of a complex measure is
given as application.
