drss are "boxed" first order logic formulae.
two cases arise: • either a condition in the drs appears as a condition in one of the sub-drs; that is the case for condition 1 which appears in the sub-drs labelled π 1 ; • or it is expressed through a discourse relation; that is the case for condition 3 with R 1 (π 1 , π 2 ) → condition 3 , which means that R 1 (π 1 , π 2 ) must have condition 3 among its consequences: no other element is in charge of expressing condition 3 .