 For instance , in electronic circuit design , static <unk> logic blocks can be represented as an acyclic system of logic gates that <unk> a function of an input , where the input and output of the function are represented as individual bits . In general , the output of these blocks cannot be used as the input unless it is captured by a register or state element which maintains its acyclic properties . Electronic circuit <unk> either on paper or in a database are a form of directed acyclic graphs using instances or components to form a directed reference to a lower level component . Electronic circuits themselves are not necessarily acyclic or directed . 
