The NOGOOD node with the CP justification, in other words, represents (and records for future use) the logical link existing between the contradiction and the set of nodes from which the contradiction derives.
In this case there is only one assumption, i.e. the node N1. That assumption has to be retracted in order to eliminate the contradiction. For making OUT the node N1, some node of its OUT-list is made IN, in this case N2. The way used for making it IN is t
N2 Day (M) ° wedn (SL (5) ()) justified
So consistency is restored:
N1 Day (M) = wedn. (SL ( ) (N2)) OUT
N2 Day (M) ° wedn (SL (5) ()) IN
N3 Time(M) = 9.00 (SL (37, 43) ( )) IN
N4 Contrad.-1 (SL (1, 3) ( )) OUT
N5 Nogood -1 (CP 4 (1, 3) ( )) IN
Note that N3 is not dependent on N1 and therefore the effort needed to derive it is not going to be repeated later.