Szukana fraza: [Abstract = "First, we consider non\-linear discrete\-time and continuous\-time systems with unknown inputs. The problem of reconstructing an input using the information given by an output equation is investigated. Then we examine a control problem for non\-linear discrete\-time hereditary systems, i.e. the problem of finding a control which drives the state of the system from its initial value to a given desired final state."]